Antibiotic resistance

Enferm Infecc Microbiol Clin, 2002 Aug-Sep, 20(7), 341 - 5
{Structure and function of integrons}; Sabate M et al.; Integrons are genetic elements known for their role in the acquisition and expression of genes conferring antibiotic resistance . Integrons have an integrase gene (intI), an attachment site (attI), into which individual resistance genes are inserted and a promotor sequence (Pant), allowing expression of resistance genes (cassette-associated genes), which do not have promotors . Integrase recognizes 59-be, a specific sequence in certain resistance genes, which is captured by recombination at the attI attachment site . The fragment intI - attI is highly conserved in all integrons and is called 59 -CS.Integrons have been classified according to the sequence of their integrase and the ones most frequently detected in isolated clinical strains belong to Class I . Class I integrons contain the 59 -CS region followed by gene cassettes in a variable region and finally, a conserved region known as 39 -CS containing two genes, the quaternary ammonium resistance gene (qacEDI) and the sulphonamide resistance gene (sul1); both genes are fixed in this structure . Accordingly, the structure of a Class 1 integron would be IntI - attI {R11 R21.} - qacED1 - sul1.Integrons are probably not mobile, but they are often found in transposons within conjunctive plasmids, which assures their mobility, as can be seen by their wide diffusion among bacteria.

J Perinat Neonatal Nurs, 2002 Sep, 16(2), 54 - 72
Vancomycin and gentamicin in neonates: hindsight, current controversies, and forethought; Dawson PM; The use of both vancomycin and gentamicin in the treatment of suspected or documented neonatal infections, while routine, is a challenge for bedside and advanced practice nurses caring for neonates in intensive care units . A review of the background information surrounding neonatal infections as well as the history, intended use, and the pharmacokinetic and pharmacodynamic properties of vancomycin and gentamicin is presented with the goal of aiding in proper treatment with these two medications . Specific attention is given to doses in special situations, means of drug monitoring, strategies for avoiding antibiotic resistance, alternative medication choices, and areas for future investigation.

Semin Respir Infect, 2002 Sep, 17(3), 184 - 8
Resistance mechanisms; Acar JF; During the past decade, there has been extensive investigation of bacterial resistance mechanisms.The interplay of genetic and antibiotic factors on antibiotic resistance are multiple and complex . Antibiotic resistance is the clinical expression of these factors . This article reviews the most studied and understood mechanisms of resistance in bacterial species in which resistance problems have clinical significance . Besides plasmid mediated resistance some resistance problems among respiratory pathogens are clonal resistance . The precise cause of this actual genetic event causing bacterial mutation recombination and selection is not always clear . Although resistance mechanisms may be identical within an antibiotic class, expression of resistance often varies among antibiotics of the same class .

Med J Aust, 2002 Sep 16, 177(6), 325 - 9
11: Antibiotic resistance; Collignon PJ; Antibiotic resistance is a consequence of antibiotic use - we need to use antibiotics less and to use them prudently . Plans to combat antibiotic resistance were recently proposed by the World Health Organization, a United States interagency taskforce and the Australian Joint Expert Technical Advisory Committee on Antibiotic Resistance . Prudent antibiotic use includes not using antibiotics when benefit is minimal (eg, in many respiratory tract infections), using narrow-spectrum antibiotics whenever possible and using optimal dosages and regimens . The need for antibiotic therapy can be reduced by preventing infections through vaccination, infection control measures and improved sanitation . Surveillance of antibiotic resistance is needed to target interventions for minimising antibiotic use . More research is needed into new antibiotics and regimens and into improving medical devices and protocols to prevent infection . Some simple changes to practice could reduce development and spread of antibiotic resistance

Vaccine, 2002 Sep 10, 20(27-28), 3379 - 88
PCR-generated linear DNA fragments utilized as a hantavirus DNA vaccine; Johansson P et al.; The field of DNA vaccines has grown rapidly, and since most such vaccines involve the inoculation of large circular DNA molecules previously propagated in bacteria, several inconveniences (e.g . the presence of antibiotic resistance genes, impurities from bacterial cultures or inefficient uptake of the large and bulky plasmid DNA molecules to the nucleus) are debated . In this study, we have explored the possibility of using smaller and more flexible PCR-generated linear DNA fragments instead . Phosphorothioate (PTO)-modified primers were used successfully to protect the PCR-generated DNA fragments from exonuclease degradation, and by using a nuclear localization signal-peptide to target the linear DNA to the nucleus the immune response against the encoded antigen was further improved . This approach was tested in cell culture using a sensitive reporter system and in vivo with DNA encoding the amino-terminus of the Puumala hantavirus nucleocapsid protein . Our results indicate that linear DNA fragments have a great potential as a genetic vaccine and phosphorothioate modification in combination with a nuclear localization signal peptide increase the stability and targets the linear DNA molecules to the nucleus resulting in an improved biological response examined both in vitro and in vivo.

J Mol Recognit, 2002 May-Jun, 15(3), 113 - 25
Conformational analysis of bacterial cell wall peptides indicates how particular conformations have influenced the evolution of penicillin-binding proteins, beta-lactam antibiotics and antibiotic resistance mechanisms; Grail BM et al.; Our aim was to use a conformational analysis technique developed for peptides to identify structural relationships between bacterial cell wall peptides and beta-lactam antibiotics that might help to explain their different actions as substrates and inhibitors of penicillin binding proteins (PBPs) . The conformational forms of the model cell wall peptide Ac-L-Lys(Ac)-D-Ala-D-Ala are described by just a few backbone torsion combinations: three C-terminal carboxylate regions, with Tor8 (psi(i+1)) ranges of D3 region (50 degrees to 70 degrees ), D6 region (140 degrees to 170 degrees ) and D9 region (-50 degrees to -70 degrees ) are combined with either of two Tor6 (phi(i))-Tor4 (psi(i)) combinations, C4 region (-50 degrees to -80 degrees ) with B8 region (-40 degrees to -70 degrees ) or C11 region (30 degrees to 50 degrees ) with B2 region (30 degrees to 70 degrees ) . From these results, and comparisons with conformational analyses of various beta-lactams and Ac-L-Lys(Ac)-D-Ala-D-Lac, it is concluded that molecular recognition of cell wall peptide substrates by PBPs requires conformers with backbone torsion angles of D3C4B8 . beta-Lactam antibiotics are constrained compounds with fewer conformational forms; these match well the backbone torsions of cell wall peptides at D3C4, allowing their recognition and acylation by PBPs, whereas their unique Tor4 produces differently orientated CO and N atoms that appear to prevent subsequent deacylation, leading to their action as suicide substrates . The results are also related to the selective pressures involved in evolution of beta-lactamases from PBPs . From analysis of conformers of Ac-L-Lys(Ac)-D-Ala-D-Ala and the vancomycin-resistant analogue Ac-L-Lys(Ac)-D-Ala-D-Lac, it is concluded that vancomycin may recognise D6C11B2 conformers, giving it complementary substrate specificity to PBPs . This approach could have applications in the rational design of antibiotics targeted against PBPs and their substrates .

Helicobacter, 2002, 7 Suppl 1, 56 - 62
Helicobacter pylori infection in geriatrics; Pilotto A et al.; The prevalence of Helicobacter pylori infection increases with age worldwide . However, the percentage of H . pylori-positive elderly patients who are tested and treated for their infection remains very low . We now have data that demonstrate the benefit of curing H . pylori infection in elderly patients with H . pylori-associated peptic ulcer disease and severe chronic gastritis . Furthermore, the cure of H . pylori may prevent progression of intestinal metaplasia and gastric atrophy . Studies are needed to clarify the role of eradication for elderly patients who have nonulcer dyspepsia, gastroesophageal reflux disease and who use nonsteroidal anti-inflammatory drugs . H . pylori infection may be easily diagnosed by histological evaluation, rapid urease test or culture performed on gastric biopsies taken during endoscopy . However, the biopsy site must be carefully selected in elderly patients . For noninvasive monitoring of H . pylori infection after treatment, the 13C-urea breath test has significantly higher accuracy than serology in the elderly . The role of the H . pylori stool antigen test in old age still needs to be clarified . One-week PPI-based triple therapy regimens including clarithromycin, amoxycillin and/or nitroimidazoles are highly effective and well tolerated in elderly patients . Low doses of both PPIs and clarithromycin (in combination with standard doses of amoxycillin or nitroimidazoles) are sufficient . Antibiotic resistance and low compliance are the main factors related to treatment failure at any age.

Biochemistry, 2002 Sep 3, 41(35), 10764 - 70
Cloning, overexpression, and purification of aminoglycoside antibiotic 3-acetyltransferase-IIIb: conformational studies with bound substrates; Owston MA et al.; Aminoglycoside 3-acetyltransferase-IIIb (AAC3), which acetylates N3 amine of aminoglycoside antibiotics, was cloned from P . Aeruginosa and purified from overexpressing E . coli BL21 (DE3) cells . Bound conformations of kanamycin A and ribostamycin, in the active site of the enzyme that modifies the essential N3B of aminoglycoside antibiotics, were determined by NMR spectroscopy . Experimentally determined interproton distances were used in a simulated annealing protocol to determine enzyme-bound conformations of both antibiotics . Two conformations, consistent with the NOE restraints, were determined for ribostamycin . The only difference between the two conformers was the orientation of the A ring with respect to the rest of the molecule . The average glycosidic dihedral angles were Phi(1A) = -22 degrees +/- 3 and Psi(1A) = -42 degrees +/- 1 (conformer 1) and Phi(1A) = -67 degrees +/- 0.7 and Phi(1A) = -59 degrees +/- 0.8 (conformer 2) . Three conformers were determined for the enzyme-bound kanamycin A . Two conformers of kanamycin A were matched well with the two conformers of ribostamycin when the A and the B rings of the antibiotics were superimposed . Conformations of kanamycin A and ribostamycin were compared to those of other aminoglycosides that are bound to different enzymes and RNA . The results lend further support to our earlier hypothesis that the A and B rings of aminoglycosides adopt a conformation that is recognized not only by the aminoglycoside-modifying enzymes but also by RNA (Serpersu, E . H., Cox, J . R., Digiammarino, E . L., Mohler, M . L., Akal, A., Ekman, D . R., and Owston, M . (2000) Cell Biochem . Biophys . 33, 309-321) . These results may be useful in designing new antibiotics to combat the antibiotic resistance against infectious diseases.

J Mol Evol, 2002 Sep, 55(3), 314 - 21
Phylogenetic analysis shows that the OXA beta-lactamase genes have been on plasmids for millions of years; Barlow M et al.; The OXA genes encode a class of beta-lactamases that confer resistance to a wide range of beta-lactam antibiotics . To determine whether the diversity of the OXA beta-lactamases is the result of recent or ancient events, and to determine whether mobilization of the OXA genes from chromosomes to plasmids occurred recently or long ago, we have constructed a Bayesian phylogeny of the OXA beta-lactamase genes . Analysis of that phylogeny shows that much of the diversity is the result of ancient events and that the OXA genes were mobilized from chromosomes to plasmids on at least two independent occasions that occurred millions of years ago . That observation contradicts the commonly held impression that mobilization of antibiotic resistance genes is strictly the result of modern use of antibiotics.

J Med Microbiol, 2002 Aug, 51(8), 705 - 9
Antibiotic susceptibility of Helicobacter pylori in Germany: stable primary resistance from 1995 to 2000; Wolle K et al.; The issue of antibiotic resistance in Helicobacter pylori is of particular concern and has become an important factor leading to eradication failure . This paper reports the prevalence of primary resistance to clarithromycin, amoxicillin, metronidazole and tetracycline among H . pylori isolates in the north-eastern part of Germany . A total of 1644 clinical H . pylori isolates was investigated over a period of 6 years from 1995 to 2000 . The MICs were determined by the Etest . The overall rate of primary resistance was 26.2% for metronidazole and 2.2% for clarithromycin . No significant changes in the resistance rates during the period of investigation were observed . No isolate was resistant to amoxicillin or tetracycline . PCR-RFLP analysis for the detection of point mutations associated with clarithromycin resistance was performed with 36 H . pylori isolates . The A --> G transition mutation at position 2143 was detected in 19 H . pylori isolates (52.8%), whereas the mutation at position 2142 was found in 13 isolates (36.1%).

J Am Chem Soc, 2002 Aug 14, 124(32), 9422 - 30
Molecular dynamics at the root of expansion of function in the M69L inhibitor-resistant TEM beta-lactamase from Escherichia coli; Meroueh SO et al.; Clavulanate, an inhibitor for beta-lactamases, was the very first inhibitor for an antibiotic resistance enzyme that found clinical utility in 1985 . The clinical use of clavulanate and that of sulbactam and tazobactam, which were introduced to the clinic subsequently, has facilitated evolution of a set of beta-lactamases that not only retain their original function as resistance enzymes but also are refractory to inhibition by the inhibitors . This article characterizes the properties of the clinically identified M69L mutant variant of the TEM-1 beta-lactamase from Escherichia coli, an inhibitor-resistant beta-lactamase, and compares it to the wild-type enzyme . The enzyme is as active as the wild-type in turnover of typical beta-lactam antibiotics . Furthermore, many of the parameters for interactions of the inhibitors with the mutant enzyme are largely unaffected . The significant effect of the inhibitor-resistant trait was a relatively modest elevation of the dissociation constant for the formation of the pre-acylation complex . The high-resolution X-ray crystal structure for the M69L mutant variant revealed essentially no alteration of the three-dimensional structure, both for the protein backbone and for the positions of the side chains of the amino acids . It was surmised that the difference in the two enzymes must reside with the dynamic motions of the two proteins . Molecular dynamics simulations of the mutant and wild-type proteins were carried out for 2 ns each . Dynamic cross-correlated maps revealed the collective motions of the two proteins to be very similar, yet the two proteins did not behave identically . Differences in behavior of the two proteins existed in the regions between residues 145-179 and 155-162 . Additional calculations revealed that kinetic effects measured experimentally for the dissociation constant for the pre-acylation complex could be mostly attributed to the electrostatic and van der Waals components of the binding free energy . The effects of the mutation on the behavior of the beta-lactamase were subtle, including the differences in the measured dissociation constants that account for the inhibitor-resistant trait . It would appear that nature has selected for incorporation of the most benign alteration in the structure of the wild-type TEM-1 beta-lactamase that is sufficient to give the inhibitor-resistant trait.

Crit Care Med, 2002 Aug, 30(8), 1877 - 82
Pilot study of antibiotic cycling in a pediatric intensive care unit; Moss WJ et al.; OBJECTIVE: This pilot study was performed to determine the safety and size of effect of antibiotic cycling to reduce colonization and infection with antibiotic-resistant bacteria . DESIGN: Open, observational study . SETTING: The study was performed in a 16-bed pediatric medical-surgical intensive care unit . PATIENTS: Critically ill children requiring antibiotic therapy . INTERVENTIONS: Three antibiotic classes were systematically cycled for 3-month intervals over 18 months . Antibiotic regimens were used for all empirical therapy and continued if the bacterial isolate was susceptible . MEASUREMENTS: The primary outcome was colonization with antibiotic-resistant bacteria, determined by surveillance cultures obtained twice monthly from all patients in the unit . Rates of antibiotic-resistant, nosocomial blood stream infections, and risks of colonization over calendar time in the intensive care unit were also evaluated . MAIN RESULTS: The cycling of broad-spectrum, empirical antibiotics was safe and did not generate increased antibiotic resistance nor select for new organisms . Over the study period, the trend in prevalence of children colonized with antibiotic-resistant bacteria was from 29% to 24% (p =.41) . The effect on prevalence of resistant blood stream infections was similar (p =.29) . Changes in individual risks of colonization with resistant bacteria over calendar time were consistent with the ecologic effect in size and direction . CONCLUSIONS: Results of this pilot intervention suggest that cycling antibiotics may be a safe and viable strategy to minimize the emergence of antibiotic resistance in intensive care units . A definitive study will require a randomized and controlled trial of only four pediatric intensive care units over an 18-month period.

J Ind Microbiol Biotechnol, 2002 Aug, 29(2), 60 - 9
The detection of diverse aminoglycoside phosphotransferases within natural populations of actinomycetes; Anderson AS et al.; The conserved nature of the genes that code for actinomycete secondary metabolite biosynthetic pathways suggests a common evolutionary ancestor and incidences of lateral gene transfer . Resistance genes associated with these biosynthetic pathways also display a high degree of similarity . Actinomycete aminoglycoside phosphotransferase antibiotic resistance enzymes (APH) are coded for by such genes and are therefore good targets for evaluating the bioactive potential of actinomycetes . A set of universal PCR primers for APH encoding genes was used to probe genomic DNA from three collections of actinomycetes to determine the utility of molecular screening . An additional monitoring of populations for the predominance of specific classes of enzymes to predict the potential of environmental sites for providing isolates with interesting metabolic profiles . Approximately one-fifth of all isolates screened gave a positive result by PCR . The PCR products obtained were sequenced and compared to existing APH family members . Sequence analysis resolved the family into nine groups of which six had recognizable phenotypes: 6'-phosphotransferase (APH(6)), 3'-phosphotransferase (APH(3)), hydroxyurea phosphotransferase (HUR), peptide phosphotransferase, hygromycin B phosphotransferase (APH(7")) and oxidoreductase . The actinomycetes screened fell into seven groups, including three novel groups with unknown phenotypes . The strains clustered according to the environmental site from where they were obtained, providing evidence for the movement of these genes within populations . The value of this as a method for obtaining novel compounds and the significance to the ecology of antibiotic biosynthesis are discussed.

Expert Opin Investig Drugs, 2002 Aug, 11(8), 1127 - 38
New strategies for the prevention and treatment of Helicobacter pylori infection; Ruggiero P et al.; Helicobacter pylori infects the stomach of > 50% of the human population worldwide, with higher prevalence in the developing countries . A strict correlation between H . pylori infection and gastroduodenal diseases has been demonstrated, including gastritis, peptic ulcer and gastric cancer . Current therapies against H . pylori consist of an antisecretory plus antibiotics . These therapies are effective in 80 - 90% of the cases; presently, no alternative therapies have been shown to give comparable or better results . There are two main reasons for therapy failure: poor compliance, which results in cure discontinuation, and antibiotic resistance . To overcome the drawbacks inherent to any antibiotic therapy, a prophylactic vaccine seems to be the most reasonable approach . Vaccines have been developed based on data obtained in animal models, a number of which are currently in Phase I clinical trials, in some cases giving encouraging data for safety and immunogenicity . In the absence of any immunological correlate of protection against H . pylori, it will be possible to evaluate the efficacy of these vaccines only in large Phase III clinical trials.

Expert Opin Investig Drugs, 2002 Aug, 11(8), 1023 - 32
Reversing antibiotic resistance; Hodgkinson R et al.; Over the past decade many well-tried chemotherapeutic agents have lost their effectiveness . This is due to a phenomenon referred to as multi-drug resistance . The most likely cause of multi-drug resistance is an increase in the activity of an efflux pump mediated through the actions of a P-glycoprotein . There is a continuing search, not only for new chemotherapeutic agents, but also for agents that can reverse the acquired resistance to existing agents.

Bull Acad Natl Med, 2001, 185(9), 1683 - 97
{Towards non-viral gene therapy}; Scherman D; In vivo gene transfer might be useful for gene therapy application such as cancer or therapeutic neoangiogenesis . Non-viral gene therapy, which uses plasmid DNA as expression vector, presents several advantages . In particular, plasmids are more simple to develop than viral vectors, and they are not immunogenic . We have improved the safety and efficiency of non viral gene therapy by optimizing plasmid backbone and developing new gene delivery technologies . Backbone optimized minicircles are gene expression vectors of minimal size, which are devoid of bacterial origin of replication and of antibiotic resistance gene . Triple helix affinity chromatography allows rapid obtention of highly purified plasmid preparation, with minimal contamination by endotoxins and bacterial chromosomal linear DNA . Electrotransfer is a physical gene delivery technique with leads to high transgene expression in muscle and tumors after direct intratissular injection . In skeletal muscle, plasmid DNA electrotransfer leads to sustained protein production, for more than 18 months, and the transgene products can be released in the circulation . Preclinical evidence suggests that this technology might be useful for the treatment of hemophilia, beta-thalassemia, rheumatoid arthritis, or metabolic disorders . Finally, chemical DNA delivery vectors might prove useful for the targeting of disseminated metastasis.

Bull Soc Pathol Exot, 2002 Jun, 95(2), 66 - 70
{Antibiotic resistance of Helicobacter pylori in Reunion Island: therapeutic consequences}; Picot S et al.; The aims of this paper were to assess resistance of Helicobacter pylori to antibiotics included in the so-called French triple regimens and to identify the possible causes of therapeutic failure in Reunion island . Antibiotic resistance was determined for 109 strains . All the strains were sensitive to amoxicillin and tetracycline, 93.6% were sensitive to ciprofloxacin, 92.7% to erythromycin and 60.6% to metronidazole . Fifty three patients who had previously tested positive for H . pylori received for one week regimen of amoxicillin (1 g bd), clarithromycin (0.5 g bd) and omeprazole (20 mg bd) . Eradication rate after therapy was of 73.6% . Therapeutic failure was analysed for 9 patients using random amplified polymorphic DNA and the presence or not of antibiotic resistance . One cause of failure is clarithromycin resistance . These data show that triple therapy can be used in Reunion Island . In case of failure, sensitivity must be detected because the rate of resistance to metronidazole is over 30%.

Drug Resist Updat, 2002 Apr, 5(2), 73 - 87
Emerging resistance to antibiotics against respiratory bacteria: impact on therapy of community-acquired pneumonia in children; Esposito S et al.; Perhaps because of its etiologic complexity, community-acquired pneumonia (CAP) in infants and children remains a significant problem worldwide . Over the last few years, difficulties related to CAP treatment in children have greatly increased because of the emergence of resistance to the most widely used antibiotics against some of the bacterial pathogens involved in the development of the disease . There are few data describing the impact of antibiotic resistance on clinical outcomes in CAP, but many experts believe that the clinical impact is limited . We here discuss the prevalence of different etiologic agents in CAP of children, the diagnostic criteria, problems related to antibiotic resistance, therapeutic strategies, and future implications .

Curr Opin Infect Dis, 2002 Aug, 15(4), 401 - 5
Infection in the intensive care unit: prevention strategies; Bonten MJ; PURPOSE OF THE REVIEW: Nosocomial infections remain among the most common treatment complications, particularly in intensive care unit patients . In many countries antibiotic resistance is increasingly hampering treatment of these infections . Preventive strategies have therefore become more important and have been directed both against the development of specific infections and against the spread of antibiotic-resistant pathogens . The present review addresses recent data on the latter issue . In particular, we discuss the first approaches to use mathematical modelling as a tool to analyse and guide strategies to prevent infection, and the effects of antibiotic cycling . RECENT FINDINGS: Several mathematical models to address the dynamics of pathogen transmission in hospital settings have been developed . One of the models may allow quantification of the effects of different strategies to prevent infection in intensive care units, and another may be used to determine the relative importance of different colonization routes, without the need for expensive genotyping methods . The results of the first prospective studies on antibiotic cycling are inconclusive, and again mathematical modelling may help to provide testable hypotheses for such interventions . Finally, recent studies have shown that alcohol-based hand rubs are better than hand washing with soap and water for most hand disinfection purposes . SUMMARY: The first results of use of mathematical modelling to guide infection control strategies should be subjected to prospective, empirical testing in order to determine their clinical usefulness . More rigorously designed studies are needed to determine the benefits of antibiotic cycling strategies . Hands should be disinfected with alcohol-based hand rubs, which should be available at each bedside.

Curr Opin Infect Dis, 2002 Aug, 15(4), 395 - 400
Antibiotic policies and control of resistance; Gould IM; PURPOSE OF THE REVIEW: The current worldwide pandemic of antibiotic resistance shows no signs of abating . It is clear that it is driven mainly by heavy and often inappropriate antibiotic use . Although control measures are widely practised, it is important that we assess their efficacy critically in order to concentrate expensive control efforts where they will be most effective . The past year has seen much activity in this area, with evidence-based assessments of the literature according to strict guidelines, as well as progress in basic science studies of mechanisms of resistance, and their causes and relations to pathogenicity and adaptability . RECENT FINDINGS: The present review summarizes current developments in the causes of antibiotic resistance, the classification of antibiotic stewardship and control measures, the evidence base for their efficacy, current problems in hospital practice, the adaptability of bacteria, the content of antibiotic policies and anticipated activities . SUMMARY: The conclusions from the published literature are that much of it that pertains to changing prescribing practices does not stand up to modern evidence-based analysis concepts . Nevertheless, we can learn from experience in changing other areas of medical practice . We must be pragmatic and must not expect to change the world, but rather take it step by step, recognizing barriers and measuring outcomes and quality indicators . Studies into the molecular basis of resistance confirm the superb genetic adaptability of micro-organisms . They will always be several steps ahead of us . Nevertheless, we are learning how to modify our prescribing habits to minimize resistance, not only by using antibiotics less frequently but also by altering dosing schedules in various ways.

Curr Opin Infect Dis, 2002 Aug, 15(4), 387 - 94
Nosocomial pneumonia; Mehta RM et al.; PURPOSE OF REVIEW: Despite abundant literature on the management of nosocomial pneumonia, a number of aspects, from diagnosis to the therapy of nosocomial pneumonia, are still controversial . This review focuses on recent advances that can aid in the day-to-day care of these critically ill patients . RECENT FINDINGS: The risk factors for nosocomial pneumonia in specific subsets of trauma, postoperative and burn injury patients have been identified, with emphasis on the type of pneumonia developing in these populations - early or late onset nosocomial pneumonia . Resolution of nosocomial pneumonia, in terms of improvement of clinical parameters such as oxygenation, fever, leukocytosis and bacterial eradication, has been reported, and these data can lead to a better understanding of the natural course of the disease . The importance of initial, accurate empiric therapy in improving mortality in nosocomial pneumonia has been reinforced by multiple studies . Newer techniques to study colonization and the routes of spread of pathogenic organisms in the intensive care unit are adding to our understanding of how pneumonia develops, the role of infection control measures and the types of strategies that are needed for prevention . Oral decontamination is showing promise as a technique to prevent ventilator-associated pneumonia, and noninvasive ventilation has been shown to be useful in various etiologies of respiratory failure, with the beneficial effect of reducing the incidence of ventilator-associated pneumonia and its associated mortality . The implementation of protocolized treatment guidelines and antibiotic rotation policies are emerging as useful tools for reducing the frequency of antibiotic resistance and the impact of nosocomial pneumonia . SUMMARY: There is a better understanding of nosocomial pneumonia risk factors, mechanisms of bacterial colonization, and resolution of illness, with exciting developments in prevention and treatment emerging, and these data can help us achieve more effective management of this complex illness.

Semin Pediatr Infect Dis, 2002 Apr, 13(2), 129 - 33
Influenza virus vaccines in children and their impact on the incidence of otitis media; Rafei K; Otitis media has been identified as the most frequent reason for outpatient antibiotic therapy . Several studies have linked viral respiratory infections with bacterial otitis media . In light of rising concerns about antibiotic resistance, the possibility of reducing the incidence of otitis media through vaccination against respiratory viruses has received increasing attention . This article reviews inactivated and live attenuated influenza virus vaccines and their possible impact on the incidence of otitis media . Inactivated and live attenuated influenza virus vaccines are safe and immunogenic in children older than 6 months and are linked to a decrease in the incidence of otitis media . Influenza vaccination of infants younger than 6 months has resulted in less predictable immunogenicity and deserves further investigation.

Antimicrob Agents Chemother, 2002 Aug, 46(8), 2636 - 9
Salicylate reduces susceptibility of Mycobacterium tuberculosis to multiple antituberculosis drugs; Schaller A et al.; Salicylate induces multiple antibiotic resistance in various bacterial species . Here we investigated the effect of salicylate on the susceptibility of Mycobacterium tuberculosis to a range of antituberculosis (anti-TB) drugs . In the presence of salicylate, the killing effects of isoniazid (INH), rifampin (RMP), ethambutol (EMB), streptomycin (STR), and p-aminosalicylate (PAS) were reduced, as shown with a tetrazolium redox dye viability assay and a bacterial survival assay . Salicylate-induced resistance was more pronounced for PAS, STR, and EMB but was not apparent for INH and RMP when salicylate and the anti-TB agents were incorporated into 7H11 plates . The significance of these findings for TB treatment needs to be further evaluated in vivo.

Curr Biol . 2002 Jul 9;12(13):R441.
Flaws bug television gene drama; Dixon B; MEDIAWATCH: Rejection of scientific advice by the writers of a BBC thriller based on the consequences of genetic modification of wheat with an antibiotic-resistance gene renders the plot absurd, writes Bernard Dixon.

J Am Geriatr Soc, 2002 Jul, 50(7 Suppl), S242 - 6
Management of antibiotic-resistant bacteria; Norman DC; Optimizing the management of antibiotic resistance is an important strategy in improving outcomes for infectious diseases in older persons . Strategies that manage antibiotic resistance must take into account all clinical settings, because resistant pathogens previously seen only in acute care facilities are becoming increasingly common in long-term care facilities . Recently, modest improvement in therapeutic options for the treatment of infections due to resistant pathogens has become available because of the development of newer antibiotics . Some of these drugs are briefly discussed in this review, but the best strategy is to limit the potential for the development of resistance and transmission of these pathogens . This can best be accomplished by minimizing misuse of antibiotics and maximizing adherence to basic hygiene standards.

Clin Infect Dis, 2002 Aug 1, 35(3), 298 - 304 Epub 2002 Jul 08.
Helicobacter pylori: consensus and controversy; Passaro DJ et al.; Helicobacter pylori is uniquely adapted to colonize the human stomach . Infection leads to a range of subclinical and clinical outcomes that depend on properties of the infecting strain, the host, and the environment . Eradication therapy is indicated for infected persons who develop peptic ulcer disease or gastric lymphoma or who are beginning long-term treatment with nonsteroidal anti-inflammatory drugs . However, treatment may worsen gastroesophageal reflux disease and increase the risk of esophageal cancer . H . pylori infections can be diagnosed noninvasively and can be eradicated with approximately 85% success by a variety of multidrug, 7-14-day regimens . Unfortunately, antibiotic resistance is affecting treatment effectiveness in the United States and abroad . A more complete understanding of the variation in H . pylori pathogenesis should lead to clearer recommendations about treatment for infected persons who have neither peptic ulcer disease nor gastric lymphoma.

Transgenic Res, 2002 Jun, 11(3), 315 - 9
Selection of transgenic Xenopus laevis using antibiotic resistance; Moritz OL et al.; We previously established lines of transgenic Xenopus laevis expressing green fluorescent protein (GFP) or GFP fusion proteins in the rod photoreceptors of their retinas under control of the X . laevis opsin promoter, which permits easy identification of transgenic animals by fluorescence microscopy . However, GFP tags can alter the properties of fusion partners, and in many circumstances a second selectable marker would be useful . The transgene constructs we used also encode a gene that confers resistance to the antibiotic G418 in cultured mammalian cells . In this study, we show that F2 transgenic offspring of these animals are more resistant to G418 toxicity than their non-transgenic siblings, as are primary transgenic X . laevis . G418 resistance can be used as a selectable marker in transgenic X . laevis, and possibly other aquatic transgenic animals.

J Infect Chemother, 2002 Jun, 8(2), 155 - 62
Characterization of cefotaxime-resistant Escherichia coli isolates from a nosocomial outbreak at three geriatric hospitals; Ma L et al.; Over a 22-month period, there was an unusual upsurge in the incidence of cefotaxime-resistant Escherichia coli among hospitalized patients in three geriatric hospitals in the same district . Sixteen highly cefotaxime-resistant strains were obtained from clinical specimens during the period January 1996 through October 1997 . All strains were characterized by antibiotic resistance pattern analysis, the detection of the TEM- and Toho-type beta-lactamase or CTX-M-type beta-lactamase gene by polymerase chain reaction (PCR), plasmid profiling, Southern hybridization analysis, and pulsed-field gel electrophoresis (PFGE) . Antibiotic resistance analysis showed that all strains were highly resistant to ampicillin, piperacillin, carbenicillin, cephaloridine, and cefotaxime; intermediately resistant to cefoxitin; moderately susceptible to moxalactam and ceftazidime; and susceptible to imipenem . Detailed analysis of beta-lactamase content revealed that all cefotaxime-resistant strains harbored a plasmid that mediated an extended-spectrum beta-lactamase of the Toho-type or CTX-M-type by PCR and Southern hybridization analysis . PCR detection showed that all the E . colistrains, except for strains TUM1023, TUM1101, TUM1227, and TUM1229, also possessed bla(TEM) genes . Furthermore, Southern hybridization analysis showed that all strains, except for TUM1102, gave a similar signal with the Toho probe . The PFGE profiles of the E . colistrains obtained with XbaI showed four patterns that correlated well with the plasmid profiles . The Dice value of 15 strains, including Toho-2 producer (TUM1083), for their PFGE patterns indicated a similarity of 80% or more . Our results suggest that 15 of the 17 Toho type beta-lactamase-producing E . coli strains (including strain TUM1083) studied belong to a single epidemic strain, while the other two strains are different from them, and the Toho-type or CTX-M-type beta-lactamase encoding gene may be acquired by plasmid conjugation or a mobile element.

Curr Drug Targets, 2002 Aug, 3(4), 345 - 9
Mutation and evolution of antibiotic resistance: antibiotics as promoters of antibiotic resistance?
Blazquez J, Oliver A, Gomez-Gomez JM.
Antibiotic resistance appearance and spread have been classically considered the result of a process of natural selection, directed by the use of antibiotics . Bacteria, that have to face the antibiotic challenge, evolve to acquire resistance and, under this strong selective pressure, only the fittest survive, leading to the spread of resistance mechanisms and resistant clones . Horizontal transference of resistance mechanisms seems to be the main way of antibiotic resistance acquisition . Nevertheless, recent findings on hypermutability and antibiotic-induced hypermutation in bacteria have modified the landscape . Here, we present a review of the last data on molecular mechanisms of hypermutability in bacteria and their relationship with the acquisition of antibiotic resistance . Finally, we discuss the possibility that antibiotics may act not only as selectors for antibiotic resistant bacteria but also as resistance promoters.

Protein Eng, 2002 Jun, 15(6), 463 - 70
Improving a circularly permuted TEM-1 beta-lactamase by directed evolution; Osuna J et al.; Circular permutation of proteins is a powerful technique to explore the importance of the polypeptide secondary structure order for attaining the final three-dimensional structure . Here, we designed a circular permutation of the TEM beta-lactamase in order to produce a new domain-forming amino acid arrangement in the polypeptide sequence . Closing the normal N- and C-termini with the connecting peptide GGS and creating new N- and C-termini at position 216, produces a severely impaired permuted protein . Introduction of a connector with random components allows the isolation of enzymes with better activities and indicates a selection for a potential helix-stop signal at the new super-secondary motif . We applied several directed-evolution cycles, starting from permuted enzymes with each of the two different connecting peptides, and selecting for antibiotic resistance and isolated several mutants with resistance levels close to those of the wild-type enzyme . We also analyze some of the data collected on the outcomes and paths of these evolutionary experiments . A purified sixth cycle variant with connector peptide GGS showed catalytic efficiency values approximately 8% of the natural enzyme.

J Mol Biol, 2002 Jun 28, 320(1), 85 - 95
Evolution of an antibiotic resistance enzyme constrained by stability and activity trade-offs; Wang X et al.; Pressured by antibiotic use, resistance enzymes have been evolving new activities . Does such evolution have a cost? To investigate this question at the molecular level, clinically isolated mutants of the beta-lactamase TEM-1 were studied . When purified, mutant enzymes had increased activity against cephalosporin antibiotics but lost both thermodynamic stability and kinetic activity against their ancestral targets, penicillins . The X-ray crystallographic structures of three mutant enzymes were determined . These structures suggest that activity gain and stability loss is related to an enlarged active site cavity in the mutant enzymes . In several clinically isolated mutant enzymes, a secondary substitution is observed far from the active site (Met182-->Thr) . This substitution had little effect on enzyme activity but restored stability lost by substitutions near the active site . This regained stability conferred an advantage in vivo . This pattern of stability loss and restoration may be common in the evolution of new enzyme activity . (c) 2002 Elsevier Science Ltd.

J Am Coll Nutr, 2002 Jun, 21(3 Suppl), 166S - 173S
Food safety evaluation of crops produced through biotechnology; Chassy BM; Agricultural biotechnology has been widely adopted in agriculture but is also the focus of controversy . Questions have arisen regarding food and environmental safety . In the US, responsibility for ensuring agricultural and environmental safety is delegated to the USDA and EPA, respectively . The FDA has primary responsibility for food safety, with the exception that the EPA has responsibility for the safety of proteins in plants associated with insect defense mechanisms . The food safety assessment, whether performed by the FDA or the EPA, requires evaluation of the safety of 1) the newly added DNA, 2) the safety of the newly introduced gene product and 3) the overall safety of the balance of the food . A paradigm called "Substantial Equivalence" guides the assessment . The principal food safety issues for new varieties crops are 1) potential toxicity of the newly introduced protein(s), 2) potential changes in allergenicity, 3) changes in nutrient composition, 4) unintended effects giving rise to allergenicity or toxicity and 5) the safety of antibiotic resistance marker-encoded proteins included with the transgene . All of these must be taken in the context of the predicted range of dietary exposures . The evaluation seeks to establish that there is a "reasonable likelihood of safety" and that new varieties are as safe as or safer than crops produced by traditional methods . Indeed, after extensive safety testing and some five years of experience with such crops in the marketplace, there is not a single report that would lead an expert food scientist to question the safety of such transgenic crops now in use.

Commun Dis Public Health, 2002 Mar, 5(1), 7 - 12
Impact of infections on primary care--greater than expected; Fleming DM et al.; Though infection has declined as a cause of death it consumes a major proportion of primary care resources, and because of antibiotic resistance is increasingly important . We examined the burden of illness attributable to infection in primary care by analysing data from the fourth practice-based national morbidity survey which monitored all consultations by diagnosis in 470,000 persons over a 12 month period from September 1991 to August 1992 . Rates of persons consulting, new episodes of illness and consultations were calculated according to the list of infections published by Wilson and Bhopal (W&B list), and as amended by the Communicable Disease Surveillance Centre (CDSC list); selected comparisons were made with national data on hospital derived finished consultant episodes and deaths . Forty-one percent of all registered persons consulted on at least one occasion during the year for infection (estimated by either list) . Infections accounted for 40% of all new episodes of illness and 29% of all consultations; respiratory infections accounted for approximately half the infection total . New episode rates were highest in children aged less than 1 year and lowest in males 25-54 years and females 55-64 years . Except in infancy, rates were higher in females . There were 734 episodes of infection annually per 1,000 population reported in general practice compared with 20 per 1,000 finished consultant episodes . The average episode of infection prompted 1.2 general practice consultations . Improved management through more precise diagnosis by near patient tests is desirable, but is unlikely to be obtained cost effectively if consultation numbers or the time spent is substantially increased . These results emphasise the importance of adequate training for general practitioners in the natural history, epidemiology, diagnosis and treatment (pharmacology) of infection.

Res Microbiol, 2002 May, 153(4), 199 - 204
Structure and role of coupling proteins in conjugal DNA transfer; Gomis-Ruth FX et al.; Type IV secretory systems are transmembrane bacterial multiprotein complexes . They are pivotal for conjugation, bacterial-induced plant tumour formation, toxin secretion and mammalian pathogen intracellular activity . These systems are involved in the spread of antibiotic resistance genes among bacteria by enabling conjugative DNA transfer . When such translocons transport DNA, they require the assistance of multimeric integral inner membrane proteins, the type IV coupling proteins . Its structural prototype is plasmid R388 TrwB protein, responsible for coupling the relaxosome with the DNA transport apparatus during bacterial conjugation . Its monomeric molecular structure is reminiscent of ring helicases and AAA ATPases . The quaternary structure is made up by six equivalent protomers featuring a flattened sphere resembling F1-ATPase, with a central channel traversing the particle, thus connecting cytoplasm and periplasm.

Physiol Plant, 2002 Mar, 114(3), 429 - 438
Genetic transformation of cauliflower (Brassica oleracea var . botrytis) by direct DNA uptake into mesophyll protoplasts; Radchuk VV et al.; Mesophyll protoplasts of Brassica oleracea var . botrytis were successfully transformed using polyethylene glycol (PEG) . The success of plant transformation depended on both gene transfer and plant regeneration . Parameters, such as PEG and vector concentrations and heat shock conditions were tested in experiments on transient expression of the beta-glucuronidase (EC 3.2.1.31) gene and the most suitable conditions for DNA uptake were determined . Two antibiotic resistance marker genes for neomycin phosphotransferase (EC 2.7.1.95) and hygromycin phosphotransferase (EC 2.7.1.104), and three vector plasmids with different lengths were used to obtain stable transformants.

J Biol Chem, 2002 Aug 30, 277(35), 32149 - 56 Epub 2002 Jun 10.
The structural bases of antibiotic resistance in the clinically derived mutant beta-lactamases TEM-30, TEM-32, and TEM-34; Wang X et al.; Widespread use of beta-lactam antibiotics has promoted the evolution of beta-lactamase mutant enzymes that can hydrolyze ever newer classes of these drugs . Among the most pernicious mutants are the inhibitor-resistant TEM beta-lactamases (IRTs), which elude mechanism-based inhibitors, such as clavulanate . Despite much research on these IRTs, little is known about the structural bases of their action . This has made it difficult to understand how many of the resistance substitutions act as they often occur far from Ser-130 . Here, three IRT structures, TEM-30 (R244S), TEM-32 (M69I/M182T), and TEM-34 (M69V), are determined by x-ray crystallography at 2.00, 1.61, and 1.52 A, respectively . In TEM-30, the Arg-244 --> Ser substitution (7.8 A from Ser-130) displaces a conserved water molecule that usually interacts with the beta-lactam C3 carboxylate . In TEM-32, the substitution Met-69 --> Ile (10 A from Ser-130) appears to distort Ser-70, which in turn causes Ser-130 to adopt a new conformation, moving its O gamma further away, 2.3 A from where the inhibitor would bind . This substitution also destabilizes the enzyme by 1.3 kcal/mol . The Met-182 --> Thr substitution (20 A from Ser-130) has no effect on enzyme activity but rather restabilizes the enzyme by 2.9 kcal/mol . In TEM-34, the Met-69 --> Val substitution similarly leads to a conformational change in Ser-130, this time causing it to hydrogen bond with Lys-73 and Lys-234 . This masks the lone pair electrons of Ser-130 O gamma, reducing its nucleophilicity for cross-linking . In these three structures, distant substitutions result in accommodations that converge on the same point of action, the local environment of Ser-130.

Toxicol Lett, 2002 Feb 28, 127(1-3), 337 - 40
Clinical risk assessment of GM foods; Lack G; The main concerns about adverse effects of genetically modified (GM) foods on health are the transfer of antibiotic resistance, toxicity and allergenicity . There are two issues from an allergic standpoint . First, the transfer of a known allergen may occur from a crop into a non-allergenic target crop . The second scenario is the creation of a neo-allergen where de novo sensitisation occurs in the population . The first scenario occurred in 1996 when the 2S albumen protein from Brazil nut was transferred into soy bean (N . Engl . J . Med . 334 (1996) 688) . 2S albumen was found to be a major Brazil nut allergen and the newly expressed protein in transgenic soy retained its allergenicity . Patients allergic to Brazil nuts and not to soy bean now showed an IgE mediated response towards GM soy bean . We argue that it is possible to prevent such occurrences by doing IgE-binding studies and taking into account physico-chemical characteristics of proteins and referring to known allergen databases . The second possible scenario of de novo sensitisation does not easily lend itself to risk assessment . We compare GM technology to traditional plant breeding and food processing methods . There is no evidence that the technology used for the production of GM foods poses an allergic threat per se compared to other methodologies widely accepted in the food industry . We need to proceed cautiously in the future, assessing individual GM foods on the basis of their individual merits and risks prior to introducing them into the market.

Aliment Pharmacol Ther, 2002 Jul, 16 Suppl 4, 105 - 13
Review article: Helicobacter pylori infection from pathogenesis to treatment--a critical reappraisal; Vaira D et al.; The main areas of this review are Helicobacter pylori and disease pathogenesis; the relationship of H . pylori to lower gastrointestinal diseases, liver disease and extra-gastrointestinal conditions; the relationship of H . pylori to gastro-oesophageal reflux disease; infection in the very young and very old; diagnostic techniques; and management of H . pylori infections with particular emphasis on eradication regimens and antibiotic resistance.

Am Fam Physician, 2002 May 15, 65(10), 2039 - 44
Diagnosis and management of acute bronchitis; Knutson D et al.; Acute bronchitis is one of the top 10 conditions for which patients seek medical care . Physicians show considerable variability in describing the signs and symptoms necessary to its diagnosis . Because acute bronchitis most often has a viral cause, symptomatic treatment with protussives, antitussives, or bronchodilators is appropriate . However, studies indicate that many physicians treat bronchitis with antibiotics . These drugs have generally been shown to be ineffective in patients with uncomplicated acute bronchitis . Furthermore, antibiotics often have detrimental side effects, and their overuse contributes to the increasing problem of antibiotic resistance . Patient satisfaction with the treatment of acute bronchitis is related to the quality of the physician-patient interaction rather than to prescription of an antibiotic.

Hum Reprod, 2002 Jun, 17(6), 1433 - 6
Chlamydia trachomatis in subfertile women undergoing uterine instrumentation . The clinician's role; Macmillan S; Most women attending a fertility clinic will undergo uterine instrumentation either diagnostically and/or therapeutically . This places them at potential risk of chlamydial pelvic inflammatory disease . Clinicians remain unclear about the roles of screening, serology and prophylactic antibiotics . A review of the evidence suggests that women <25 years and those older with risk factors, men with risk factors and gamete donors should have their lower genital tract screened for Chlamydia trachomatis by a sensitive test . More information is required before screening men by age can be recommended . Serology in its present form cannot be advocated as a screening tool . Those women with a past history of chlamydial morbidity or a diagnosis of tubal pathology should, in addition to screening, be covered with prophylactic antibiotics when undergoing uterine instrumentation . The partner should be screened for sexually transmitted infections . Non-selective use of prophylactic antibiotics serves only to increase the problem of antibiotic resistance and maintain the bacterial load of chlamydia in the community.

Gene Ther, 2002 Jun, 9(11), 679 - 82
Extrachromosomal genes: a powerful tool in gene targeting approaches; Colosimo A et al.; Several studies, some of which have been updated during the recent workshop entitled Genome Medicine: Gene Therapy for the Millennium (Rome, 30 September-3 October 2001), have highlighted the usefulness of extrachromosomal or episomal genes in gene targeting strategies . Due to the selectable nature of antibiotic resistance and reporter genes, targeted correction of mutated versions of these extrachromosomal genes allows an accurate quantification of correction frequency . In addition, these model systems facilitate and speed up the optimization of critical parameters for the successful application of gene targeting approaches . In fact, type of cell line, gene delivery system, molar ratio of episomal target/therapeutic constructs, nature and design of therapeutic complexes and different recombinative proteins may be critical for the actual feasibility of each method . Although virus-based approaches are now being investigated as well, this article is focusing on the targeted correction of extrachromosomal genes by the use of small DNA fragments (SDF), chimeric RNA/DNA oligonucleotides (RDO) and triplex-forming oligonucleotides (TFO).

Prof Nurse, 2001 Sep, 17(1), 56 - 9
Addressing the problem of increased antibiotic resistance; Kelly J; Growing bacterial resistance to antibiotics is causing grave concern in both community and hospital settings . Mismanagement has been identified as the main cause . The problem can be addressed at ground level by careful use of antibiotics, through meticulous personal and environmental hygiene and preventive infection-control measures.

J Pediatr Nurs, 2002 Apr, 17(2), 126 - 32
Prescribing practices that promote antibiotic resistance: strategies for change; Larrabee T; Approximately 90% of all upper respiratory infections are caused by viruses, yet antibiotics are prescribed for 50% to 70% of patients who seek medical care for these conditions (Neiderman, Skerrett, & Yamauchi, 1998) . Prescribing antibiotics for conditions for which there is no proven benefit is not a harmless practice; it contributes to the development of antibiotic resistance (Ware, 2000) . This article will discuss the magnitude of the problem of antibiotic resistance as it relates to pediatric outpatient upper respiratory tract infection and otitis media, analyze practitioner prescribing practices that contribute to widespread antibiotic use, and suggest provider and patient intervention to improve the rational use of antibiotics .

Philos Trans R Soc Lond B Biol Sci, 2002 Apr 29, 357(1420), 505 - 19
The evolution of drug-resistant malaria: the role of drug elimination half-life; Hastings IM et al.; This paper seeks to define and quantify the influence of drug elimination half-life on the evolution of antimalarial drug resistance . There are assumed to be three general classes of susceptibility of the malaria parasite Plasmodium falciparum to a drug: Res0, the original, susceptible wildtype; Res1, a group of intermediate levels of susceptibility that are more tolerant of the drug but still cleared by treatment; and Res2, which is completely resistant to the drug . Res1 and Res2 resistance both evolve much faster if the antimalarial drug has a long half-life . We show that previous models have significantly underestimated the rate of evolution of Res2 resistance by omitting the effects of drug half-life . The methodology has been extended to investigate (i) the effects of using drugs in combination, particularly when the components have differing half-lives, and (ii) the specific example of the development of resistance to the antimalarial pyrimethamine-sulphadoxine . An important detail of the model is the development of drug resistance in two separate phases . In phase A, Res1 is spreading and replacing the original sensitive forms while Res2 remains at a low level . Phase B starts once parasites are selected that can escape drug action (Res1 genotypes with borderline chemosensitivity, and Res2): these parasites are rapidly selected, a process that leads to widespread clinical failure . Drug treatment is clinically successful during phase A, and health workers may be unaware of the substantial changes in parasite population genetic structure that predicate the onset of phase B . Surveillance programs are essential, following the introduction of a new drug, to monitor effectively changes in treatment efficacy and thus provide advance warning of drug failure . The model is also applicable to the evolution of antibiotic resistance in bacteria: in particular, the need for these models to incorporate drug pharmacokinetics to avoid potentially large errors in their predictions.

Hindustan Antibiot Bull, 1999 Feb-Nov, 41(1-4), 25 - 31
Antibiotic resistance--a close look; Bhattacharyya BK; The discovery of antibiotic greatly improved the human health care system . But today we are facing the problem of antibiotic resistance due to uncontrolled use of the compound . This can be by passed by controlled use of antibiotic and formulation of newer ones.

J Dairy Sci, 2002 Apr, 85(4), 992 - 1001
Farmers' choice of medical treatment of mastitis in Danish dairy herds based on qualitative research interviews; Vaarst M et al.; A qualitative research study was conducted to describe and analyze farmers' perspectives on their own choices regarding decisions to have cows treated for mastitis . Through qualitative research interviews of 16 Danish dairy farmers, four levels of the decision-making process used by farmers to decide whether or not to treat a cow with antibiotics were identified . Those levels were: 1) symptom level (seriousness of the mastitis case), 2) cow level (to the extent a cow fulfilled goals of the farmer and the herd), 3) herd level (the situation of the herd, e.g., in relation to milk quota), and 4) level of alternatives (whether the farmer regards such practices as blinding of teats or homoeopathy as serious alternatives to antibiotic treatment) . All four levels could be recognized in all herds, but with differing weights and relative importance across herds . Directions of different possibilities within each level also varied among farmers . By identifying those four levels, a model for understanding the farmers' choices is provided . This provides background for dialogue with each farmer about choices in the context of each specific herd . It also provides insight into implications of mastitis treatments for effective treatment versus issues of antibiotic resistance when discussing choices on a more general level . Communication and understanding between farmers and their veterinarians and cattle-oriented advisors is essential . Farmers were shown to be coherent in their choices of treatment, but their decisions often seemed to differ from normal veterinary recommendations . Such differences have to be understood and implemented into effective decisions for the whole farm.

J Appl Microbiol, 2002, 92(6), 1116 - 22
Novel intercellular communication system in Escherichia coli that confers antibiotic resistance between physically separated populations; Heal RD et al.; AIMS: To determine whether intercellular signalling can occur between physically separated populations of Escherichia coli . METHODS AND RESULTS: Intercellular signalling between physically discrete populations of E . coli BL21 was analysed in bi-partite Petri dishes . Transfer of a growth-promoting signal resulted in induction of resistance to the antibiotic ampicillin . Optimal expression of the signal occurred when the signalling population was established as a bacterial lawn for 24 h . This represented an entry into the stationary phase of growth, as indicated by the expression profile of the RNA polymerase subunit sigma38 (sigmaS; sigma S) . The growth-promoting effect was also observed when E . coli DH5alpha (luxS-) was used as the signalling population . Preventing passage of air between the two populations resulted in a complete cessation of the growth-promoting effect . CONCLUSIONS: A growth-promoting signal occurs between physically separated cultures of E . coli . The exact nature of the signal remains to be determined but does not involve the production of autoinducer-2 from the luxS gene . Signal transmission is likely to involve airborne transfer of a signal species . SIGNIFICANCE AND IMPACT OF THE STUDY: Intercellular signalling systems exist in bacteria that enable antibiotic resistance to be conferred between physically separated populations.

Am J Gastroenterol, 2002 Apr, 97(4), 857 - 60
Colloidal bismuth subcitrate-based twice-a-day quadruple therapy as primary or salvage therapy for Helicobacter pylori infection; Dore MP et al.; OBJECTIVE: Helicobacter pylori (H . pylori) eradication rates in northern Sardinia using standard 1-wk triple therapies (i.e., a proton pump inhibitor and two antibiotics) are typically <60%, primarily because of antibiotic resistance . The aim of this study was to test b.i.d . quadruple therapy as primary and as salvage therapy in this population . METHODS: This was a prospective, single center study of consecutive dyspeptic H . pylori-infected patients . Therapy consisted of omeprazole 20 mg, tetracycline 500 mg, metronidazole 500 mg, and bismuth subcitrate caplets 240 mg, all b.i.d . with the midday and evening meals for 14 days . H . pylori status was evaluated by 13C-urea breath test and histology before and 4-6 wk after therapy . Eradication was defined as no positive test . RESULTS: We enrolled 118 consecutive dyspeptic patients (mean age 46 yr; 73 men, including 15 with peptic ulcer disease) . Of the patients, 42 (38%) had failed prior therapy: twice in 21 cases, three times in 12, and four or more times in nine . The intention-to-treat cure rate was 95% (110 of 116) (95% CI = 90-98%) overall, and 98% per protocol, irrespective of diagnosis, age, prior treatment failure, or smoking status . Moderate or severe side effects were experienced by only 5% of patients . CONCLUSIONS: Bismuth subcitrate-based b.i.d . quadruple therapy was an excellent primary and salvage therapy and should be considered as first line therapy.

Wien Med Wochenschr, 2002, 152(5-6), 141 - 7
{Therapy of Helicobacter pylori infection: "Who to treat, how to treat?"}; Sebesta Ch et al.; Seventeen years after detection of Helicobacter pylori as the pathogenetic factor in a variety of gastroduodenal diseases, current treatment options are about 90% effective in eradicating the bacteria and thereby curing the affiliated disorders . In 1987 successful therapy has been shown to reduce relapse rates of duodenal and gastric ulcers dramatically and clinicians all over the world started to perform a still ongoing vast number of trials searching for the most effective first--and in case of failure, second line-treatment options . The results of these trials led to strictly evidence based and generally accepted guidelines formulated by Consensus Reports . The main questions "who to treat" and "how to treat" can be answered by using the categories "strongly recommended indications", "advisable indications" that leave some space for individual decisions, and consideration of first and second time eradication therapies together as a package . Treatment has become simple: three drugs, twice daily for one week . All available protone pump inhibitors (PPI) have been shown to be effective and presently there is only a few antibiotic agents used in combination and defined dose, proven to ensure treatment success . The future will encounter clinicians with problems concerning patient compliance, antibiotic resistance and more effective second and even third line therapies . This paper will focus on two subjects: indications ("who to treat") and evidence-based eradication regimens ("how to treat") in a reasonable setting close to everyday clinical practice.

Emerg Infect Dis, 2002 May, 8(5), 496 - 502
Sentinel surveillance: a reliable way to track antibiotic resistance in communities?
Schrag SJ, Zell ER, Schuchat A, Whitney CG.
We used population-based data to evaluate how often groups of randomly selected clinical laboratories accurately estimated the prevalence of resistant pneumococci and captured trends in resistance over time . Surveillance for invasive pneumococcal disease was conducted in eight states from 1996 to 1998 . Within each surveillance area, we evaluated the proportion of all groups of three, four, and five laboratories that estimated the prevalence of penicillin-nonsusceptible pneumococci (%PNSP) and the change in %PNSP over time . We assessed whether sentinel groups detected emerging fluoroquinolone resistance . Groups of five performed best . Sentinel groups accurately predicted %PNSP in five states; states where they performed poorly had high between-laboratory variation in %PNSP . Sentinel groups detected large changes in prevalence of nonsusceptibility over time but rarely detected emerging fluoroquinolone resistance . Characteristics of hospital-affiliated laboratories were not useful predictors of a laboratory's %PNSP . Sentinel surveillance for resistant pneumococci can detect important trends over time but rarely detects newly emerging resistance profiles.

J Am Chem Soc, 2002 May 15, 124(19), 5333 - 40
An ultrahigh resolution structure of TEM-1 beta-lactamase suggests a role for Glu166 as the general base in acylation; Minasov G et al.; Although TEM-1 beta-lactamase is among the best studied enzymes, its acylation mechanism remains controversial . To investigate this problem, the structure of TEM-1 in complex with an acylation transition-state analogue was determined at ultrahigh resolution (0.85 A) by X-ray crystallography . The quality of the data was such as to allow for refinement to an R-factor of 9.1% and an R(free) of 11.2% . In the resulting structure, the electron density features were clear enough to differentiate between single and double bonds in carboxylate groups, to identify multiple conformations that are occupied by residues and loops, and to assign 70% of the protons in the protein . Unexpectedly, even at pH 8.0 where the protein was crystallized, the active site residue Glu166 is clearly protonated . This supports the hypothesis that Glu166 is the general base in the acylation half of the reaction cycle . This structure suggests that Glu166 acts through the catalytic water to activate Ser70 for nucleophilic attack on the beta-lactam ring of the substrate . The hydrolytic mechanism of class A beta-lactamases, such as TEM-1, appears to be symmetrical, as are the serine proteases . Apart from its mechanistic implications, this atomic resolution structure affords an unusually detailed view of the structure, dynamics, and hydrogen-bonding networks of TEM-1, which may be useful for the design of inhibitors against this key antibiotic resistance target.

Ir J Med Sci, 2002 Jan-Mar, 171(1), 42 - 3
Vancomycin-resistant peritonitis associated with peritoneal dialysis: a cause for concern; O'Riordan A et al.; BACKGROUND: Peritonitis resulting from peritoneal dialysis (PD) remains a serious cause of morbidity and even mortality among dialysis patients . AIM: To highlight the danger of antibiotic resistance in patients on dialysis who have received multiple courses of antibiotics . METHODS: Two cases are reported in which the patients developed peritonitis resistant to vancomycin . CONCLUSIONS: Multi-drug resistance is a growing danger . It is imperative to use the most appropriate antibiotics in the proper dosage . If infections persist, early removal of the catheters is essential . The use of antibiotics in PD patients needs to be limited . Sensitivity patterns of the cultured organisms must be monitored regularly as the lack of vigilance may help accelerate the development of the so-called 'super bug' resistant to all antibiotics.

Vaccine, 2002 May 6, 20(15), 1999 - 2003
Issues for improving multiplasmid DNA vaccines for HIV-1; Muthumani K et al.; Since the first reports of plasmid vaccines, there have been substantial changes made to the design of plasmid backbones, as well as to the antibiotic resistance markers chosen for clinical vectors compared with first generation vectors . These changes aid manufacturing, production and scale up and at the same time aid conceptual safety by limiting the ability of the vaccines to transfer useful genetic selection genes to other bacterial infectious agents . In contrast, there has been little change to the original promoters or polyadenlyation tracts in the last decade.We have learned that these first generation plasmid vaccines for HIV-1 appear very well tolerated in humans . However, while safe and immunogenic, improving the immune potency of DNA vaccines is a critical goal for this technology . The combination of antigens used should be carefully examined for possible immune interference . Such interference may only become apparent when each component of the vaccine is tested individually . This interference also suggests one mechanism of immune pathogenesis possibly by HIV-1 . Optimization of the immune response can come through manipulation of the transfection efficiency, expression or through the use of various T cell and B cell plasmid adjuvants . It is likely that the combination of such advancements will significantly improve the clinical phenotype of this important vaccine modality.

Plasmid, 2002 Mar, 47(2), 129 - 37
Construction of mini-Tn4001tet and its use in Mycoplasma gallisepticum; Pour-El I et al.; The Mollicutes are a group of cell-wall-less bacteria and are important plant and animal pathogens . Progress toward analyzing their pathogenic mechanisms has been hampered by the few available genetic tools . Of the two transposons shown to function in mycoplasmas, only Tn4001 is readily amenable to modification and development . One disadvantage of using Tn4001 in mycoplasmas has been independent insertion of the insertion sequence, IS256, probably as a result of inadequate control of the transposase expression in mycoplasmas . In this study, we describe the construction of a mini-Tn4001 containing the tetM antibiotic resistance gene from Tn916 . The transposase gene was placed outside the inverted repeats to lower the frequency of independent transposition events . Transposition of mini-Tn4001tet in Mycoplasma gallisepticum occurred at a frequency of 1-8 x 10(-6), a frequency similar to that of the parent transposon . Insertions of mini-Tn4001tet were random and only single insertions were observed . Several unique restriction sites between the inverted repeat sequences provide for further development of mini-Tn4001 .

Curr Opin Biotechnol, 2002 Apr, 13(2), 173 - 80
Marker-free transformation: increasing transformation frequency by the use of regeneration-promoting genes; Zuo J et al.; The generation of transgenic plants free of antibiotic resistance markers is a major challenge to plant biologists and plant breeders . Currently, there are two main strategies to achieve this goal: one approach is to excise or segregate marker genes from the host genome after regeneration of transgenic plants, and the second is based on so-called 'marker-free' transformation . Marker-free transformation has been successfully demonstrated by the use of several plant and non-plant genes that are capable of promoting explant regeneration . This approach appears not only to be effective for the generation of marker-free transgenic plants, but also has great potential to improve the transformation frequency of recalcitrant species.

Proc Natl Acad Sci U S A, 2002 Apr 16, 99(8), 5601 - 5 Epub 2002 Apr 09.
How to assess the relative importance of different colonization routes of pathogens within hospital settings; Pelupessy I et al.; The emergence of antibiotic resistance among nosocomial pathogens has reemphasized the need for effective infection control strategies . The spread of resistant pathogens within hospital settings proceeds along various routes of transmission and is characterized by large fluctuations in prevalence, which are typical for small populations . Identification of the most important route of colonization (exogenous by cross-transmission or endogenous caused by the selective pressure of antibiotics) is important for the design of optimal infection control strategies . Such identification can be based on a combination of epidemiological surveillance and costly and laborious as well as time-consuming methods of genotyping . Furthermore, analysis of the effects of interventions is hampered by the natural fluctuations in prevalence . To overcome these problems, we introduce a mathematical algorithm based on a Markov chain description . The input is longitudinal prevalence data only . The output is estimates of the key parameters characterizing the two colonization routes . The algorithm is tested on two longitudinal surveillance data sets of intensive care patients . The quality of the estimates is determined by comparing them to accurate estimates based on additional information obtained by genotyping . The results warrant optimism that this algorithm may help to quantify transmission dynamics and can be used to evaluate the effects of infection control interventions more carefully.

J Clin Pharmacol, 2002 Apr, 42(4), 461 - 6
Lack of bioequivalence of ciprofloxacin when administered with calcium-fortified orange juice: a new twist on an old interaction; Neuhofel AL et al.; Fluoroquinolones are known to interact with drugs containing multivalent ions . Current Food and Drug Administration (FDA) labeling states that ciprofloxacin and most other fluoroquinolones are safe to be given with food and dietary calcium but not calcium supplements . Although many of the currently marketed calcium fortified foods have calcium contents that usually exceed those in dietary calcium sources, it is unclear whether they represent a risk for less than optimal absorption of fluoroquinolones, which may result in subsequent clinical failures due to lack of bacterial eradication and antibiotic resistance . The purpose of this three-way, randomized, crossover study was to characterize and compare the bioequivalence of single doses of oral ciprofloxacin in 15 healthy volunteers when administered with water, concurrently with orange juice, and concurrently with calcium-fortified orange juice . Compared to the control arm, the Cmax of ciprofloxacin significantly decreased when it was given with orange juice (23%, p = 0.001) and with calcium-fortified orange juice (41%, p < 0.001) . Twenty-four-hour ciprofloxacin AUCs were also decreased for both forms of the orange juice (22% {p < 0.001} and 38% {p < 0.001}, respectively) . When compared to each other, neither of the orange juice regimens were bioequivalent to each other, with the Cmax and AUC for the fortified form being 22% (p = 0.005) and 21% (p = 0.015) lower than those of the nonfortified form . By FDA standards, although ciprofloxacin is marginally bioequivalent when administered with orange juice, it is not when it is administered with calcium-fortified orange juice . The changes in Cmax and AUC have the potential to significantly decrease clinical efficacy and promote antibiotic resistance . Not warning patients about potential food-drug interactions with fortified foods may be a major unrealized and unstudied inadvertent source of clinical failures and resistance trends with fluoroquinolones.

J Chemother, 2001 Nov, 13 Spec No 1(1), 108 - 11
Antibiotic prophylaxis in clean surgery: breast surgery and hernia repair; D'Amico DF et al.; Use of prophylactic antibiotics in clean surgery is still controversial . We reviewed the literature of the last 10 years to identify the best way to approach clean surgery . The question is more important for patients undergoing breast surgery . The presence of an infected breast wound delays the beginning of postoperative adjuvant anticancer therapy: there is good evidence to suggest that delayed adjuvant therapy compromises the outcome for patients in terms of both local control and survival . There are several clinical trials that have addressed the efficacy of prophylactic antibiotics for patients undergoing breast surgery and hernia repair . Platt et al assessed the efficacy of preoperative antibiotic prophylaxis in a clinical trial of 1218 patients undergoing clean surgery with an absolute reduction rate of 39% in wound infections . Gupta et al reported no influence on the incidence of infective complications by antibiotic prophylaxis in 357 patients undergoing elective breast surgery . Like breast surgery, use of prophylaxis in hernia repair is not clear: a prospective, randomized, double-blind, multicenter study of 619 patients assessed no benefit of antibiotic prophylaxis . On the other hand Lewis et al reported a 75% reduction of infections in low-risk patients when a single dose of cefotaxime was used in clean operations . A particularly interesting point is the use of prosthetic mesh in hernia repair and primary reconstructive surgery in breast surgery . Amland et al reported a significant reduction of the incidence of wound infections in a group of patients undergoing reconstructive breast surgery, receiving azithromycin vs placebo (5% vs 20%) . In hernia repair we stress the need to prevent wound infections: currently Liechtestein's technique is widely performed all over the world . Mesh infection is an unpleasant event that requires prosthesis removal . The lack of conclusive studies about antibiotic prophylaxis in clean surgery suggests that a single-dose of cephalosporin at the induction of anesthesia may be prudent . This procedure is certainly inexpensive and safe and, more importantly, probably does not have an impact on antibiotic resistance.

Aliment Pharmacol Ther, 2002 Apr, 16(4), 683 - 91
Review article: an approach to Helicobacter pylori infection in the elderly; Pilotto A et al.; The prevalence of Helicobacter pylori infection increases with age world-wide, reaching levels of 40-60% in asymptomatic elderly subjects and over 70% in elderly patients with gastroduodenal diseases . However, the percentage of H . pylori-positive elderly patients who are treated for their infection remains very low . Data are now available that demonstrate the benefit of curing H . pylori infection in elderly patients with H . pylori-associated peptic ulcer disease and severe chronic gastritis . Furthermore, the cure of H . pylori may prevent the progression of intestinal metaplasia and gastric atrophy . New studies are needed to clarify the role of eradication in elderly patients with non-ulcer dyspepsia and gastro-oesophageal reflux disease and in those who use non-steroidal anti-inflammatory drugs . H . pylori infection may be easily diagnosed by histological evaluation, rapid urease test or culture performed on gastric biopsies taken during endoscopy . However, the biopsy site must be carefully selected in elderly patients . For non-invasive monitoring of H . pylori infection after treatment, the 13C-urea breath test has significantly higher accuracy than serology in the elderly; further studies are needed to clarify the role of the H . pylori stool antigen test in old age . One-week proton pump inhibitor-based triple therapy regimens, including clarithromycin, amoxicillin and/or nitroimidazoles, are highly effective and well tolerated in elderly patients . Low doses of both proton pump inhibitors and clarithromycin (in combination with standard doses of amoxicillin or nitroimidazoles) are sufficient . Low compliance and antibiotic resistance are the main factors related to treatment failure in old age.

Avian Dis, 2002 Jan-Mar, 46(1), 143 - 52
Pathotypes of avian Escherichia coli as related to tsh-, pap-, pil-, and iuc-DNA sequences, and antibiotic sensitivity of isolates from internal tissues and the cloacae of broilers; Ngeleka M et al.; One hundred four Escherichia coli isolates were collected from internal tissues and the cloacae of broilers with colibacillosis or from the cloacae of healthy birds . The isolates were tested for the presence of DNA sequences for temperature-sensitive hemagglutinin (tsh), for P (pap) and F1 (pil) fimbriae, and for aerobactin synthesis (iuc) by DNA/DNA hybridization . The isolates were also tested for O1, O2, and O78 serogroups, serum and antibiotic resistance, and virulence in day-old chickens . The Tsh/Pil/Iuc was the major pathotype detected in 53.8% of isolates from internal tissues, as compared with only 28.8% of isolates from the cloacae . The Tsh/Pap/Iuc pathotype was detected at a lower frequency (15.4%) but only in isolates from internal tissues . Among the virulence-associated marker genes, tsh and iuc were detected in most of the isolates from internal tissues (90.4% and 92.3%), as compared with only 51.9% and 63.5% of isolates from the cloacae, respectively, pap was detected to a lesser extent, in 25% of isolates but only from internal tissues . In contrast to the pil gene, the tsh-, pap-, and iuc-DNA sequences were more frequently detected in isolates from internal tissues than in isolates from the cloacae . O-antigen typing revealed that 25% of isolates belonged to serogroups O1 (4.8%), O2 (9.6%), and O78 (10.6%) . Although most isolates appeared to be resistant to serum, only isolates from internal tissues were virulent in day-old chickens in contrast to isolates from the cloacae . More than 10% of isolates were resistant to most of the antibiotics used for the study . However, less resistance to enrofloxacin and norfloxacin was observed . Our data suggest that the Tsh/Pil/Iuc and Tsh/Pap/Iuc pathotypes and Tsh and Iuc virulence-associated markers are important factors of avian pathogenic E . coli . Enrofloxacin appeared to be the best choice for treatment of the infection.

J Paediatr Child Health, 2001 Dec, 37(6), 529 - 30
Perspectives on infective ear disease in indigenous Australian children; Leach AJ et al.; Australian Aboriginal children experience the highest rates of bacterial respiratory diseases reported in the literature . Neonatal acquisition of multiple bacterial pathogenic species and strains predicts persistent and severe disease throughout childhood, particularly infective ear disease . The dynamics of bacterial nasopharyngeal colonization and transmission are poorly understood . The importance of host factors, bacterial competition and co-operation in the transition from asymptomatic carriage to disease are also uncertain . Treatment outcomes are poor, possibly due to the high density of bacterial infection following early age exposure, poor compliance and increasing levels of antibiotic resistance . The relationship between antibiotic use, clinical outcomes and bacterial resistance needs to be better understood in high-risk populations if the benefits associated with treatment are to be maximized . While there is an urgent need for vaccines, the early age of infection and the high rates of transmission and bacterial antigenic diversity mean these may also be less effective than predicted from studies in low-risk populations.

Prev Med, 2002 Mar, 34(3), 346 - 52
Antibiotic use and upper respiratory infections: a survey of knowledge, attitudes, and experience in Wisconsin and Minnesota; Belongia EA et al.; BACKGROUND: Public attitudes and expectations contribute to inappropriate antibiotic prescribing and antibiotic resistance . This study assessed knowledge, attitudes, and experiences regarding antibiotic use for respiratory infection or illness . METHODS: Random-digit-dialing telephone surveys of adults and parents of children <5 years old were conducted in Wisconsin and Minnesota during 1999 . RESULTS: The survey was completed by 405 adults and 275 parents of children <5 years old . The median age was 32 years for parents and 50 years for adults . Seven percent of parents and 17% of adults believed that antibiotics are never or almost never necessary for bronchitis . More than 70% in each group believed that antibiotics are needed for green or yellow nasal drainage, and nearly half of respondents believed that they knew whether an antibiotic was needed before seeing a physician . Exposure to multiple information sources on antibiotic resistance in the past 6 months was independently associated with a knowledge score greater than or equal to the median for nine questions . CONCLUSIONS: The general public has misconceptions regarding indications for antibiotic use, and this may contribute to inappropriate prescribing . Providing multiple and varied antibiotic-related informational messages may increase knowledge of appropriate antibiotic prescribing and decrease patient demand for antibiotics . (C)2002 American Health Foundation and Elsevier Science (USA).

Mol Biochem Parasitol, 2002 Apr 9, 120(2), 195 - 204
A new expression vector for Crithidia fasciculata and Leishmania; Tetaud E et al.; Crithidia fasciculata is a monogenetic parasite of insects . It grows in fully defined media without requiring serum, which facilitates biochemical analysis . We have constructed a series of expression systems that allows expression of transfected genes in the kinetoplastid protozoa Crithidia and Leishmania . These cells can be readily transfected with plasmid DNA by electroporation and transformants selected with various antibiotic resistance markers . 5'-Trans-splicing signals and poorly defined regions within the 3'-untranslated regions of genes are required for optimal expression of genes in trypanosomatids . We, therefore, inserted the intergenic region of the C . fasciculata phosphoglycerate kinase (PGK) genes A and B, which allows polyadenylation of the target gene and spliced leader addition to the selectable marker gene . Part of the intergenic region of the PGK locus was added upstream of the target gene to permit its trans-splicing . A 3'-untranslated sequence from the Crithidia glutathionylspermidine synthetase (GSPS) was also added to allow the polyadenylation of the selectable marker gene . Genes can be readily inserted using a multiple cloning site and can be expressed as a fusion protein with a poly-histidine sequence at either the N or C-terminus or fused with green fluorescent protein . Biologically active proteins can be expressed in C . fasciculata or L . amazonensis promastigotes and purified by affinity chromatography using a metal chelating column.

Semin Respir Infect, 2002 Mar, 17(1), 57 - 64
Old and new antibiotics for pediatric pneumonia; Bradley JS; A variety of antibiotics, both parenteral and oral, are available to the clinician caring for a child with pneumonia . Although viral pathogens are the common etiologic agents causing community-acquired pneumonia, significant morbidity and mortality exists from disease caused by bacteria and atypical pneumonia agents . Treatment of nosocomial bacterial pneumonia has become particularly difficult with ever-increasing resistance documented in hospital-acquired organisms . This article discusses antibiotic therapy based on clinical presentation and based on identified pathogens, with a discussion of mechanisms of antibiotic resistance and the newer agents that have been designed to meet this continually evolving challenge.

J Biol Chem, 2002 May 17, 277(20), 18118 - 26 Epub 2002 Mar 07.
Investigation of the roles of catalytic residues in serotonin N-acetyltransferase; Scheibner KA et al.; Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase (AANAT)) is a critical enzyme in the light-mediated regulation of melatonin production and circadian rhythm . It is a member of the GNAT (GCN-5-related N-acetyltransferase) superfamily of enzymes, which catalyze a diverse array of biologically important acetyl transfer reactions from antibiotic resistance to chromatin remodeling . In this study, we probed the functional properties of two histidines (His-120 and His-122) and a tyrosine (Tyr-168) postulated to be important in the mechanism of AANAT based on prior x-ray structural and biochemical studies . Using a combination of steady-state kinetic measurements of microviscosity effects and pH dependence on the H122Q, H120Q, and H120Q/H122Q AANAT mutants, we show that His-122 (with an apparent pK(a) of 7.3) contributes approximately 6-fold to the acetyltransferase chemical step as either a remote catalytic base or hydrogen bond donor . Furthermore, His-120 and His-122 appear to contribute redundantly to this function . By analysis of the Y168F AANAT mutant, it was demonstrated that Tyr-168 contributes approximately 150-fold to the acetyltransferase chemical step and is responsible for the basic limb of the pH-rate profile with an apparent (subnormal) pK(a) of 8.5 . Paradoxically, Y168F AANAT showed 10-fold enhanced apparent affinity for acetyl-CoA despite the loss of a hydrogen bond between the Tyr phenol and the CoA sulfur atom . The X-ray crystal structure of Y168F AANAT bound to a bisubstrate analog inhibitor showed no significant structural perturbation of the enzyme compared with the wild-type complex, but revealed the loss of dual inhibitor conformations present in the wild-type complex . Taken together with kinetic measurements, these crystallographic studies allow us to propose the relevant structural conformations related to the distinct alkyltransferase and acetyltransferase reactions catalyzed by AANAT . These findings have significant implications for understanding GNAT catalysis and the design of potent and selective inhibitors.

J Am Chem Soc, 2002 Mar 13, 124(10), 2318 - 26
EPR study of substrate binding to the Mn(II) active site of the bacterial antibiotic resistance enzyme FosA: a better way to examine Mn(II); Smoukov SK et al.; FosA is a manganese metalloglutathione transferase that confers resistance to the broad-spectrum antibiotic fosfomycin, (1R,2S)-epoxypropylphosphonic acid . The reaction catalyzed by FosA involves the attack by glutathione on fosfomycin to yield the product 1-(S-glutathionyl)-2-hydroxypropylphosphonic acid . The enzyme is a dimer of 16 kDa subunits, each of which harbors one mononuclear Mn(II) site . The coordination environment of the Mn(II) in the FosA x Mn(2+) complex is composed of a glutamate and two histidine ligands and three water molecules . Here we report EPR spectroscopic studies on FosA, in which EPR spectra were obtained at 35 GHz and 2 K using dispersion-detection rapid-passage techniques . This approach provides an absorption envelope line shape, in contrast to the conventional (slow-passage) derivative line shape, and is a more reliable way to collect spectra from Mn(II) centers with large zero-field splitting . We obtain excellent spectra of FosA bound with substrate, substrate analogue phosphate ion, and product, whereas these states cannot be studied by X-band, slow-passage methods . Simulation of the EPR spectra shows that binding of substrate or analogue causes a profound change in the electronic parameters of the Mn(II) ion . The axial zero-field splitting changes from {D} = 0.06 cm(-1) for substrate-free enzyme to 0.23 cm(-1) for fosfomycin-bound enzyme, 0.28 (1) cm(-1) for FosA with phosphate, and 0.27 (1) cm(-1) with product . Such a large zero-field splitting is uncommon for Mn(II) . A simple ligand field analysis of this change indicates that binding of the phosphonate/phosphate group of substrate or analogue changes the electronic energy levels of the Mn(II) 3d orbitals by several thousand cm(-1), indicative of a significant change in the Mn(II) coordination sphere . Comparison with related enzymes (glyoxalase I and MnSOD) suggests that the change in the coordination environment on substrate binding may correspond to loss of the glutamate ligand.

BMC Biochem . 2002;3(1):4 . Epub 2002 Feb 13.
Probing substrate binding to metallo-beta-lactamase L1 from Stenotrophomonas maltophilia by using site-directed mutagenesis; Carenbauer AL et al.; BACKGROUND: The metallo-beta-lactamases are Zn(II)-containing enzymes that hydrolyze the beta-lactam bond in penicillins, cephalosporins, and carbapenems and are involved in bacterial antibiotic resistance . There are at least 20 distinct organisms that produce a metallo-beta-lactamase, and these enzymes have been extensively studied using X-ray crystallographic, computational, kinetic, and inhibition studies; however, much is still unknown about how substrates bind and the catalytic mechanism . In an effort to probe substrate binding to metallo-beta-lactamase L1 from Stenotrophomonas maltophilia, nine site-directed mutants of L1 were prepared and characterized using metal analyses, CD spectroscopy, and pre-steady state and steady state kinetics . RESULTS: Site-directed mutations were generated of amino acids previously predicted to be important in substrate binding . Steady-state kinetic studies using the mutant enzymes and 9 different substrates demonstrated varying Km and kcat values for the different enzymes and substrates and that no direct correlation between Km and the effect of the mutation on substrate binding could be drawn . Stopped-flow fluorescence studies using nitrocefin as the substrate showed that only the S224D and Y228A mutants exhibited weaker nitrocefin binding . CONCLUSIONS: The data presented herein indicate that Ser224, Ile164, Phe158, Tyr228, and Asn233 are not essential for tight binding of substrate to metallo-beta-lactamase L1 . The results in this work also show that Km values are not reliable for showing substrate binding, and there is no correlation between substrate binding and the amount of reaction intermediate formed during the reaction . This work represents the first experimental testing of one of the computational models of the metallo-beta-lactamases.

Aliment Pharmacol Ther, 2002 Mar, 16(3), 569 - 75
Effectiveness of two quadruple, tetracycline- or clarithromycin-containing, second-line, Helicobacter pylori eradication therapies; Georgopoulos SD et al.; BACKGROUND: There are no guidelines on second-line therapies for Helicobacter pylori eradication failures of omeprazole-clarithromycin-amoxicillin triple therapy . AIM: To compare the efficacy of two second-line therapies for persistent H . pylori infection . METHODS: Over a 6-year period, patients with persistent H . pylori infection following omeprazole-clarithromycin-amoxicillin eradication therapy were randomized to receive omeprazole, 20 mg twice daily, bismuth, 120 mg four times daily, metronidazole, 500 mg twice daily, and either tetracycline, 500 mg four times daily, or clarithromycin, 500 mg twice daily, given for 7 days . Before therapy, patients underwent endoscopy with biopsies for histology, culture and antibiotic susceptibility tests . H . pylori infection was confirmed by histology . RESULTS: Of the 95 randomized patients, 88 (93%) completed the study . Age, sex, smoking, ulcer/non-ulcer dyspepsia ratio and antibiotic resistance were not significantly different between the treatment groups . On intention-to-treat analysis, eradication was achieved in 41 of the 49 patients (84%; 95% confidence interval, 70.4-92.7%) and 27 of the 46 patients (59%; 95% confidence interval, 43.3-73.0%) of the tetracycline- and clarithromycin-containing groups, respectively (P=0.007) . On multivariate regression analysis, the sensitivity of H . pylori to metronidazole had a likelihood ratio of 5.2 (P=0.022), followed by the type of quadruple therapy (likelihood ratio, 4.4; P=0.036) . CONCLUSIONS: Tetracycline-containing quadruple rescue therapy is highly effective in treating H . pylori eradication failures of the omeprazole-amoxicillin-clarithromycin regimen.

J Bacteriol, 2002 Mar, 184(6), 1712 - 21
IntI2 integron integrase in Tn7; Hansson K et al.; Integrons can insert and excise antibiotic resistance genes on plasmids in bacteria by site-specific recombination . Class 1 integrons code for an integrase, IntI1 (337 amino acids in length), and are generally borne on elements derived from Tn5090, such as that found in the central part of Tn21 . A second class of integron is found on transposon Tn7 and its relatives . We have completed the sequence of the Tn7 integrase gene, intI2, which contains an internal stop codon . This codon was found to be conserved among intI2 genes on three other Tn7-like transposons harboring different cassettes . The predicted peptide sequence (IntI2*) is 325 amino acids long and is 46% identical to IntI1 . In order to detect recombination activity, the internal stop codon at position 179 in the parental allele was changed to a triplet coding for glutamic acid . The sequences flanking the cassette arrays in the class 1 and 2 integrons are not closely related, but a common pool of mobile cassettes is used by the different integron classes; two of the three antibiotic resistance cassettes on Tn7 and its close relatives are also found in various class 1 integrons . We also observed a fourth excisable cassette downstream of those described previously in Tn7 . The fourth cassette encodes a 165-amino-acid protein of unknown function with 6.5 contiguous repeats of a sequence coding for 7 amino acids . IntI2*179E promoted site-specific excision of each of the cassettes in Tn7 at different frequencies . The integrases from Tn21 and Tn7 showed limited cross-specificity in that IntI1 could excise all cassettes from both Tn21 and Tn7 . However, we did not observe a corresponding excision of the aadA1 cassette from Tn21 by IntI2*179E.

J Antimicrob Chemother, 2002 Mar, 49(3), 541 - 3
In vitro activity of rifampicin against Helicobacter pylori isolated from children and adults; Fujimura S et al.; Antibiotic resistance in Helicobacter pylori has been a growing problem with current treatment regimens . However, second-line therapy for cases with eradication failure remains to be established . The aim of this study was to evaluate (in vitro) the potential use of rifampicin for H . pylori eradication . The susceptibility of 52 H . pylori strains isolated from children and adults to amoxicillin, clarithromycin, metronidazole and rifampicin was determined . Forty H . pylori isolates susceptible to these antibiotics were investigated for in vitro inducement of resistance . All isolates were susceptible to rifampicin . None of the H . pylori isolates tested acquired rifampicin resistance during prolonged exposure in in vitro inducement experiments . It is suggested that rifampicin has stable activity against H . pylori.

Clin Microbiol Infect, 1998 Apr, 4(4), 213 - 219
Isolation and characterization of enteroaggregative Escherichia coli (EAggEC) by genotypic and phenotypic markers, isolated from diarrheal children in Congo; Jalaluddin S et al.; OBJECTIVE: To determine the prevalence of enteroaggregative Escherichia coli (EAggEC) in African diarrheal children in Lwiro, Congo, to characterize EAggEC isolates by possible genotypic and phenotypic markers, and to evaluate the EAggEC probe pCVD432 in identifying EAggEC . METHODS: The Hep-2 cell adhesion assay and colony-blot hybridization assays were carried out for the identification of EAggEC . O:H serotyping, biotyping, antibiogram and plasmid-profile analysis were done . To detect the E . coli LT and ST, ELISA tests were used and, for VT, a vero cell assay was used . RESULTS: EAggEC strains were isolated from 56 out of 115 diarrheal children (48.7%): the organism was present alone and presumed to cause diarrhea in 22 (19.1%) cases . The rest of the cases were associated with two or more diarrheagenic E . coli strains . EAggEC strains were isolated from 25% of total diarrheal children (first day of isolation) and 8.86% of age-matched healthy individuals (p<0.03) . This isolation rate was significantly higher than the one found for other diarrheagenic E . coli strains . In parallel, we evaluated the sensitivity and specificity of EAggEC probe pCVD432, and found that it had 56% sensitivity with 100% specificity compared with the Hep-2 cell test . EAggEC isolates were characterized by serotyping, biotyping, antibiotic resistance pattern, plasmid profiling and toxin production analysis . They did not produce any one of these classical toxins and nor did they relate to any particular serotypes . Plasmid analysis of the 79 EAggEC isolates (n=315) showed seven different profiles . Ten resistance patterns were identified and 34 strains were sensitive to all drugs . There was no association between plasmid profiles and antibiotic resistance patterns . All 16 classical E . coli biotypes were found in this small EAggEC population . CONCLUSIONS: EAggEC has been emerging as a cause of childhood diarrhea in African children in Congo . From the accumulated data it was found that there is a great heterogeneity in EAggEC populations.

Methods, 2001 Nov, 25(3), 358 - 64
In vivo selection of functional variations in essential sites of ribosomal RNA; Moine H et al.; The technique of "in vivo selection of functional ribosomes" is a genetic approach to dissecting the link between the structure and function of critical sites of rRNA . This method proceeds through selection of functional variants among cells that express ribosomes from a pool of rRNA-containing randomized sites . The selection of bacterial clones with functional ribosomes is based on the use of a plasmid carrying a rRNA operon in which a site of interest has been randomized and a point mutation conferring an antibiotic resistance has been introduced . Cells expressing functional ribosomes are then selected on medium containing the antibiotic . With this approach one can isolate at once all the possible variations at a given rRNA site that are able to sustain normal ribosome function . The identification of covariations in between several nucleotides that maintain wild-type ribosome activity can thus help demonstrate the function of specific interactions in rRNA .

Virology, 2002 Feb 1, 293(1), 26 - 30
Generation of E3-deleted canine adenoviruses expressing canine parvovirus capsid by homologous recombination in bacteria; Morrison MD et al.; E3-deleted canine adenovirus type 1 (CAV-1) was generated by homologous recombination in bacterial cells, using an antibiotic resistance marker to facilitate the recovery of recombinants . This marker was flanked by unique restriction endonuclease sites, which allowed its subsequent removal and the insertion of cassettes expressing the canine parvovirus capsid at the E3 locus . Infectious virus was recovered following transfection of canine cells and capsid expression was observed by RT-PCR from one of the virus constructs . A second construct, containing a different promoter, showed delayed growth and genome instability which, based on the size difference between these inserts, suggests a maximum packaging size of 106 to 109% wild-type genome size for CAV-1.

Ther Umsch, 2002 Jan, 59(1), 51 - 5
{Successful strategies against increasing antibiotic resistance}; Sax H; The development of antibiotic resistance, known since the early days of antibiotic therapy, has accelerated in recent years and makes a postantibiotic era a realistic future scenario . The battle against increasingly resistant strains has become a major concern for infectious disease and infection control specialists worldwide . The issue has now gained heightened awareness among physicians in all specialties and the public, and has become a challenge to hospital leadership . Detailed evidence about the causes and conditions of antibiotic resistance is accumulating, but the main axes have been known for some time: overuse and misuse of antibiotic therapy and transmission of multiresistant pathogens or genetic material between humans . Selection pressure by the systematic use of antibiotics as growth promoters in animal husbandry and the resulting transmission by the food chain is an additional important cause . This overview presents the most promising strategies to contain further resistance spread and hopefully inverse the current trend.

Ther Umsch, 2002 Jan, 59(1), 5 - 10
{Mechanisms of antibiotic resistance}; Muhlemann K; Antibiotics interfere with structural and regulatory elements of bacterial cells leading to growth arrest or cell death . Bacteria have evolved a variety of strategies to overcome the effects of antibiotics . Examples are enzymatic destruction, alteration of the target, efflux and permeability changes . Resistance towards the same substance can be mediated by several mechanisms . Efflux pumps can probably act as mediators of higher resistance development . Alteration of common targets can lead to cross-resistance against several classes of antibiotics . Genetic events, such as point mutations, transfer of plasmids and gen regulation, can mediate a rapid emergence of resistance . Therefore, substances like rifampicin should be only used in combination with other drugs . Accumulation of resistance genes under common regulatory control in integrons induces co-resistance against substances of different specificity . Detailed knowledge of resistance mechanisms, their evolution and dynamics is important for a rational use of antibiotics and other strategies against antibiotic resistance.

J Appl Microbiol, 2002, 92(1), 109 - 17
Comparison of molecular and antibiotic resistance profile methods for the population analysis of Bradyrhizobium spp . (TGx) isolates that nodulate the new TGx soybean cultivars in Africa; Abaidoo RC et al.; AIMS: Comparison of molecular and antibiotic resistance profile methods to identify an easy method that can differentiate between strains of introduced Bradyrhizobium japonicum and the indigenous Bradyrhizobium spp . (TGx) isolates which nodulate the newly developed TGx soybean cultivars in Africa . METHODS AND RESULTS: Restriction fragment length polymorphism (RFLP) of 16S rDNA generated by five restriction enzymes, banding patterns in Southern hybridization using nod and nif genes as probes, and resistance patterns of the isolates to nine antibiotics, were used to group 26 Bradyrhizobium spp . (TGx) isolates and four other Bradyrhizobium strains . The clusters of isolates obtained from the four grouping methods were all different, although all methods revealed large genetic diversity among the isolates . CONCLUSIONS: Results indicate that the antibiotic resistance profile method is as good as the three molecular methods used in this study for phylogenetic grouping of the Bradyrhizobium spp . (TGx) isolates, which may serve as a basis for further characterization of selected isolates from each group . SIGNIFICANCE AND IMPACT OF THE STUDY: The antibiotic resistance profile method can be used as a simple means of assessing genetic variability and grouping of a large number of Bradyrhizobium spp . (TGx) isolates . Representative isolates from each group can then be selected for further characterization.

Aliment Pharmacol Ther, 2002 Mar, 16 Suppl 1, 24 - 30
Review article: treatment of Helicobacter pylori infection and factors influencing eradication; Qasim A et al.; Currently available Helicobacter pylori eradication therapies are considered very effective and safe . The most recent eradication guidelines proposed in the Maastricht 2-2000 Consensus Report recommend the use of proton pump inhibitors (standard b.d.) along with clarithromycin (500 mg b.d.) and amoxycillin (1000 mg b.d.) or metronidazole (500 mg b.d.) for a minimum of 7 days . The combination of amoxycillin and clarithromycin is preferred because it may favour best results with a second-line proton pump inhibitor quadruple therapy . The recommended second-line therapy includes a combination of a proton pump inhibitor (standard b.d.) with bismuth salt (subsalicylate/subcitrate 120 mg q.d.s.), metronidazole (500 mg t.d.s.), and tetracycline (500 mg q.d.s.) for a minimum of 7 days . Extended proton pump inhibitor-based triple therapy can be used if bismuth is not available . Specialists should manage subsequent failures . Based on direct and indirect evidence from well-designed studies and clinical experience, eradication is recommended in gastric and duodenal ulcers, MALToma, atrophic gastritis, postgastric cancer resection, and in first-degree relatives of gastric cancer patients . The most common reason for treatment failure is poor compliance with eradication guidelines . Antibiotic resistance may be a significant factor in certain geographical areas . Proton pump inhibitors are an integral part of the eradication regimens as proved by meta-analyses of clinical trials . Novel agents used in secondary failure are few and depend on the use of new antibiotics . The role of H . pylori-specific antibiotics, probiotics, and vaccines is not established as yet . Widespread acceptance of the eradication guidelines should be regarded as the single most important factor in eradication success.

Biotechniques, 2002 Feb, 32(2), 300, 302 - 4
Rapid construction of sequencing templates by random insertion of antibiotic resistance genes; Nabirochkina EN et al.; We describe a novel and handy method for generating a population of templates for sequencing . The method is based on the random insertion of antibiotic resistance gene in plasmid DNA digested by DNase I . The advantages of this approach are the small quantity of DNA necessary for mutagenesis and the complete independence from the restriction map of the plasmid . DNase I digestion provides a random distribution of the insertions, while antibiotic selection provides low background . We also present a convenient PCR-based procedure for the analysis and ordering of obtained insertion mutants.

J Gen Intern Med, 2002 Feb, 17(2), 87 - 94
Tensions in antibiotic prescribing: pitting social concerns against the interests of individual patients; Metlay JP et al.; BACKGROUND: To reduce the prevalence of antibiotic-resistant bacteria in the community, physicians must optimize their use of antibiotics . However, optimal use from the perspective of the community (reserving newer agents for future use) is not always consistent with optimal use from the perspective of the individual patient (prescribing newer, broader agents) . OBJECTIVES: To identify preferred patterns of antibiotic prescribing for patients with community-acquired pneumonia (CAP), measure explicit attitudes toward antibiotics and antibiotic resistance, and determine the relationship between these prescribing patterns and attitudes . DESIGN: Cross-sectional anonymous mail survey . PARTICIPANTS: National random sample of 400 generalist physicians (general internal medicine and family practice) and 429 infectious diseases specialists . MEASUREMENTS: Rank ordering of antibiotic preferences for a hypothetical outpatient with CAP and reasons for antibiotic selection . Endorsement of attitudes regarding antibiotic prescribing decisions and resistance . RESULTS: Both generalists and infectious diseases specialists were more likely to prefer newer, broader drugs for the treatment of CAP compared to older agents still recommended by national guidelines . Physicians rated the issue of contributing to antibiotic resistance lowest among 7 determinants of their choices . CONCLUSIONS: Despite national guidelines and increasing public awareness, the public health concern of contributing to the problem of antibiotic resistance does not exert a strong impact on physician prescribing decisions for CAP . Future efforts to optimize antibiotic prescribing decisions will need to consider options for increasing the impact of public health issues on the patient-oriented decisions of individual physicians.

Structure (Camb), 2002 Feb, 10(2), 269 - 79
Crystal structure of PMM/PGM: an enzyme in the biosynthetic pathway of P . aeruginosa virulence factors; Regni C et al.; The enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) from P . aeruginosa is required for the biosynthesis of two bacterial exopolysaccharides: alginate and lipopolysaccharide (LPS) . Both of these molecules play a role in the virulence of P . aeruginosa, an important human pathogen known for its ability to develop antibiotic resistance and cause chronic lung infections in cystic fibrosis patients . The crystal structure of PMM/PGM shows that the enzyme has four domains, three of which have a similar three-dimensional fold . Residues from all four domains of the protein contribute to the formation of a large active site cleft in the center of the molecule . Detailed information on the active site of PMM/PGM lays the foundation for structure-based inhibitor design . Inhibitors of sufficient potency and specificity should impair the biosynthesis of alginate and LPS, and may facilitate clearance of the bacteria by the host immune system and increase the efficacy of conventional antibiotic treatment against chronic P . aeruginosa infections.

Clin Ther, 2002 Jan, 24(1), 197 - 204
Injudicious antibiotic use: an unforeseen consequence of the emphasis on patient satisfaction?
Shapiro E.
BACKGROUND: Antibiotic resistance is an increasingly serious problem in the United States and many other parts of the world . One of the causes is the injudicious prescribing of antibiotics for self-limited viral infections . Physicians often cite parent and patient pressure as factors in their decisions to prescribe antibiotics for viral upper respiratory tract infections . OBJECTIVE: This article draws from the literature to determine the extent of patient and physician knowledge of appropriate antibiotic prescribing and to seek evidence for a link between antibiotic prescribing and patient satisfaction . Physician perception of patients' expectations regarding antibiotic use is also discussed . CONCLUSIONS: Both patients and physicians demonstrate poor knowledge regarding appropriate antibiotic prescribing for respiratory infections . Physicians are unable to judge patients' expectations accurately . Educational efforts aimed at both physicians and patients hold the most promise in decreasing unnecessary antibiotic use . These efforts include informing physicians that patient satisfaction is generally linked much more to communication than to the writing of a prescription.

Clin Ther, 2002 Jan, 24(1), 170 - 82
Antibiotic prescribing in ambulatory care settings for adults with colds, upper respiratory tract infections, and bronchitis; Cantrell R et al.; BACKGROUND: Imprudent prescribing of antibiotics for patients with colds, upper respiratory tract infections (URIs), and bronchitis may contribute to antibiotic resistance and waste economic resources . OBJECTIVE: The purpose of this study was to determine the antibiotic prescribing rate for adults diagnosed with colds, URIs, and bronchitis in 1996 and to compare these rates with those reported for 1992 . METHODS: This was a retrospective, cross-sectional analysis of a US government data base of ambulatory physician practices . The number of adults ( > or = 18 years of age) with a diagnosis of cold, URI, or bronchitis and the percentage receiving antibiotics were determined from the 1996 National Ambulatory Medical Care Survey (NAMCS) . The antibiotic prescribing rate was the main outcome measure . RESULTS: In 1996, approximately 13.9 million office visits resulted in a primary diagnosis of cold, URI, or acute bronchitis; of these visits, 46%, 47%, and 60%, respectively, resulted in the prescribing of an antibiotic . The respective rates in 1992 were 51%, 52%, and 66% . The rates of antibiotic prescribing were 12% to 16% higher when all drugs, not just the first drug listed in the NAMCS database, were analyzed . In 1996, antibiotic prescribing rates for persons 45 to 64 years of age and persons > 64 years of age were significantly lower than for those aged 18 to 44 years . CONCLUSIONS: The rates of potentially inappropriate antibiotic prescribing decreased modestly from 1992 to 1996; however, previous rates may have been underestimated . The antibiotic prescribing rates for colds, URIs, and acute bronchitis may be as high as 61%, 63%, and 72%, respectively, when all drug information is analyzed . Antibiotics are over-prescribed, which may increase antibiotic resistance and waste health care resources.

Can J Gastroenterol, 2002 Jan, 16(1), 57 - 62
Risks and benefits of Helicobacter pylori eradication: current status; Hunt RH et al.; In patients with diseases known to be associated with Helicobacter pylori infection, such as peptic ulcer, treatment of the underlying infection is the standard of care . However, in most major consensus management guidelines, including those published in Canada, widespread testing for H pylori infection is not recommended . This practice is not encouraged because of insufficient evidence of cost-benefit in gastric cancer prevention, the potential for increases in antibiotic resistance and the controversial hypothesis of potential negative effects of eradication in certain clinical entities . For example, there is insufficient evidence to recommend against eradicating H pylori discovered in a patient with symptoms of gastroesophageal reflux disease . The management guidelines designed specifically in Canada should, therefore, continue to be applied, with H pylori diagnosed and treated in appropriately selected patients.

J Clin Microbiol, 2002 Feb, 40(2), 649 - 53
Antibiotic resistance of Helicobacter pylori strains in Japanese children; Kato S et al.; The resistance of Helicobacter pylori to the recently available antibiotic treatment regimens has been a growing problem . We investigated the prevalence of H . pylori resistance to clarithromycin, metronidazole, and amoxicillin among 51 H . pylori isolates from Japanese children . In addition, the mutations of the corresponding gene were studied by PCR and restriction fragment length polymorphism analysis . Primary resistance to clarithromycin, metronidazole, and amoxicillin was detected in 29, 24, and 0% of strains, respectively . The eradication rates in clarithromycin-susceptible and -resistant strains were 89 and 56%, respectively (P < 0.05) . The prevalence of strains with acquired resistance to clarithromycin (78%) was higher than that of strains with primary resistance (P < 0.01) . Among the clarithromycin-resistant strains studied, 92% showed cross-resistance to azithromycin . No acquired resistance to amoxicillin was demonstrated . The A2144G mutation in the 23S rRNA gene was detected in 11 of 12 (92%) clarithromycin-resistant strains tested, whereas the mutation was not detected in any of the 15 susceptible strains . The deletion of the rdxA gene was not demonstrated in any of the strains . The results indicate that a high prevalence of clarithromycin-resistant strains is associated with eradication failure . Testing of susceptibility to clarithromycin is recommended.

Arch Pathol Lab Med, 2002 Feb, 126(2), 173 - 6
The use of TaqMan PCR assay for detection of Bordetella pertussis infection from clinical specimens; Chan EL et al.; OBJECTIVE: The routine clinical laboratory detection of Bordetella pertussis is through culture, which can require 5 to 7 days for the bacteria to grow . Using a polymerase chain reaction (PCR) assay can shorten this detection time while increasing the sensitivity of detection with similar specificity . This study compared culture with TaqMan PCR for detection of B pertussis in clinical specimens and the turnaround time for each assay during the pertussis season . MATERIALS AND METHODS: Nasopharyngeal swabs in Regan-Lowe transport media were collected from 1556 persons who had symptoms of whooping cough or who had had contact with infected persons; the swabs were submitted for B pertussis detection during the pertussis season . A single nasopharyngeal swab from each patient was submitted for both culture and TaqMan PCR detection . Upon receipt of the specimens, the swabs were inoculated onto Regan-Lowe agar for culture and incubated for up to 7 days . The same swab was processed for PCR detection using TaqMan PCR assay . A second nested PCR was used on positive specimens for resolution purposes . The TaqMan PCR assay was performed 3 to 5 days a week, whereas the culture was performed 6 days a week . All specimens were processed on the same day or earliest possible working day for TaqMan or culture, and specimens queued for resolution by nested PCR were batched . RESULTS: There were a total of 275 PCR positives and 28 culture positives . After resolution with the second nested PCR, the sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 97.4%, 87.6%, and 100% for TaqMan PCR and 11.6%, 100%, 100%, and 85.7% for culture . The average turnaround time for positive culture was 5.1 days, and the average turnaround time for PCR was 2.3 days . CONCLUSION: The TaqMan PCR assay has superior sensitivity and shorter turnaround time over culture because it can be finished within one working day . Furthermore, the same swab can be used for culture of the bacteria for antibiotic susceptibility testing . The early detection of pertussis using TaqMan PCR assay allows early intervention on the spread of the disease and the ability to culture the bacteria from the same swab, thereby eliminating the need for a second swab and allowing for detection of antibiotic resistance.

Hong Kong Med J, 1999 Jun, 5(2), 145 - 149
Treatment of Helicobacter pylori infection; Wu J et al.; The availability of clinic-based diagnostic tests means that screening for and the eradication of Helicobacter pylori can be done by primary care physicians . However, confusion still exists regarding indication and treatment regimens . It is universally accepted that patients with Helicobacter pylori infection and peptic ulcer disease require eradication therapy . But the benefits of Helicobacter pylori eradication in gastro-oesophageal reflux disease, non-steroidal anti-inflammatory drug-related peptic ulceration, and non-ulcer dyspepsia remain unclear . There is no evidence that the elimination of Helicobacter pylori is beneficial for asymptomatic patients or in preventing gastric cancer . One-week triple therapy with a proton pump inhibitor or ranitidine bismuth citrate in combination with clarithromycin/metronidazole and amoxycillin is the recommended first-line treatment for Helicobacter pylori infection . Problems with patient compliance and the development of antibiotic resistance are the two most important factors to consider when choosing the treatment regimen . The optimal retreatment therapy for treatment failure is still unknown, and quadruple therapy is best reserved for these cases.

Ann Pharmacother, 2002 Jan, 36(1), 148 - 54
Economic issues and antibiotic resistance in the community; Reed SD et al.; BACKGROUND: Inappropriate antibiotic use is generally considered to be the primary cause of antibiotic resistance in the community . Multiple economic factors, at the level of physicians, patients, healthcare organizations, and pharmaceutical companies, foster poor antibiotic use . OBJECTIVE: To describe the influence of economic factors on the use and development of antibiotics and to evaluate the extent to which the cost of resistance is important in the economic evaluation of antibiotic products . DATA SOURCES: Literature identified through MEDLINE (1966-May 2001), bibliographies from relevant articles, government reports, and proceedings from conferences about antibiotic resistance . DATA SYNTHESIS: Economic factors at all levels of the healthcare system contribute to the inappropriate use of antibiotics in the community setting . Relatively little economic research has been published on antibiotic resistance, and very few cost-effectiveness analyses of antibiotic treatment alternatives have explicitly included the cost of resistance . CONCLUSIONS: A better understanding of economic factors that influence the prescribing, marketing, and development of antibiotics could lead to more successful efforts at curtailing the growth of antibiotic resistance in the community setting.

J Bacteriol, 2002 Feb, 184(4), 947 - 51
Gene transfer in Mycoplasma pulmonis; Teachman AM et al.; Experiments were undertaken to examine gene transfer in Mycoplasma pulmonis . Parent strains containing transposon-based tetracycline and chloramphenicol resistance markers were combined to allow transfer of markers . Two mating protocols were developed . The first consisted of coincubating the strains in broth culture for extended periods of time . The second protocol consisted of a brief incubation of the combined strains in a 50% solution of polyethylene glycol . Using either protocol, progeny that had acquired antibiotic resistance markers from both parents were obtained . Analysis of the progeny indicated that only the transposon and not flanking genomic DNA was transferred to the recipient cell . Gene transfer was DNase resistant and probably the result of conjugation or cell fusion.

J Chemother, 2001 Dec, 13(6), 587 - 94
Antibiotic resistance: prospects for the new millennium; Daw MA et al.; Antibiotic resistance, which has been recognized to be an important clinical problem, varies in prevalence from one country to another and among the pathogens themselves . This has great clinical, economic, political and environmental implications worldwide . Strict adherence to the ongoing measures of infection control, education and antibiotic policy does minimize antibiotic resistance . The limits surrounding such approaches make consideration of new strategies become inevitable . These may include the use of new therapeutic modalities, probiotics, prebiotics and the cationic peptides . Multidisciplinary action by governments, drug industry, academicians and legislators should also be considered to overcome such a global problem . It is better that we try to prevent antibiotic resistance, rather than having to deal with it once it occurs . It is hoped that the present review will provide useful data on antibiotic resistance and assist in making rational choices to overcome this emerging problem.

Ter Arkh, 2001, 73(11), 67 - 70
{Clinical aspects of typhoid fever epidemic in migrants}; Makhnev MV; AIM: To study clinical features of typhoid fever (TF) in migrants (subjects in military service in Tadjikistan) . MATERIAL AND METHODS: In chronic water epidemic TF symptoms were studied in 547 young soldiers and officers serving in Tadjikistan with incomplete biological and/or professional adaptation . RESULTS: In most cases TF onset was acute, the course was severe with fever and intoxication . TF clinical picture was similar to that of the beginning of the XX century . Despite antibiotic resistance of the causative agent, recurrences and serious complications were rare, lethal outcomes were not registered . CONCLUSION: Relatively low frequency of recurrences and severe complications, absence of lethal outcomes in this study can be explained by long-term combined etiotropic therapy and good premorbid condition of the patients.

Funct Integr Genomics, 2000 Nov, 1(3), 200 - 6
A high-throughput system for genome-wide measurement of genetic recombination in Arabidopsis thaliana based on transgenic markers; Barth S et al.; A high-throughput system for the measurement of recombination frequencies in the genetic model plant, Arabidopsis thaliana, is described . It is based on 21 mono-transgenic isogenic lines harboring antibiotic resistance genes on all five chromosomes . Recombination between pairs of gene insertions in repulsion phase that confer resistance against kanamycin (kan) and hygromycin (hyg) is determined by a phenotypic assay of progeny (DART: Double Antibiotic Resistance Technique) . DART allows testing for the influence of numerous environmental and genetic factors, including candidate genes, on recombination frequencies in specific genomic regions as well as the entire genome . Its usefulness is demonstrated by investigating the effects of UV treatment, different temperature and phosphorus supply regimes, and sex on recombination frequencies for all five chromosomes of A . thaliana.

BMJ, 2002 Jan 5, 324(7328), 28 - 30
Effect of beta lactam antibiotic use in children on pneumococcal resistance to penicillin: prospective cohort study; Nasrin D et al.; OBJECTIVE: To examine the relation between use of antibiotics in a cohort of preschool children and nasal carriage of resistant strains of pneumococcus . DESIGN AND PARTICIPANTS: Prospective cohort study over two years of 461 children aged under 4 years living in Canberra, Australia . MAIN OUTCOME MEASURES: Use of drugs, respiratory symptoms, and visits to doctors were documented in a daily diary by parents of the children during 25 months of observation . Isolates of pneumococci, which were cultured from nasal swabs collected approximately six monthly, were tested for antibiotic resistance . RESULTS: From the four swab collections 631 positive pneumococcal isolates from 461 children were found, of which 13.6% were resistant to penicillin . Presence of penicillin resistant pneumococci was significantly associated with children's use of a beta lactam antibiotic in the two months before each swab collection (odds ratio 2.03 (95% confidence interval 1.15 to 3.56, P=0.01)) . The odds ratio of the association remained >1 (though did not reach significance at the 0.05 level) for use in the six months before swab collection . The association was seen in children who received only penicillin or only cephalosporin antibiotics in that period . The odds ratio was 4.67 (1.29 to 17.09, P=0.02) in children who had received both types of beta lactam in the two months before their nasal swab . The modelled odds of carrying penicillin resistant pneumococcus was 4% higher for each additional day of use of beta lactam antibiotics in the six months before swab collection . CONCLUSIONS: Reduction in beta lactam use could quickly reduce the carriage rates of penicillin resistant pneumococci in early childhood . In view of the propensity of these organisms to be spread among children in the community, the prevalence of penicillin resistant organisms may fall as a consequence.

J Clin Microbiol, 2002 Jan, 40(1), 301 - 5
Antibiotic-resistant cell-detaching Escherichia coli strains from Nigerian children; Okeke IN et al.; The properties of 23 cell-detaching Escherichia coli strains that were isolated from stool specimens in Nigeria are described . Common properties of the strains included the presence of genes encoding alpha-hemolysin (100%), pyelonephritis-associated pili (100%), and cytotoxic necrotizing factor 1 (70%) as well as lactose negativity (70%) and multiple antibiotic resistance (74%) . Antibiotic resistance was shown in most cases to be transferable and associated with the presence of class 1 integrons . Phenotypic properties and pulsed-field gel electrophoresis analysis demonstrated that the majority of the strains, particularly multiply resistant, lactose-negative O4:H40 strains, were closely related . Multiply-resistant cell-detaching E . coli strains may represent an important reservoir for antibiotic resistance genes.

Mol Plant Microbe Interact, 2001 Nov, 14(11), 1312 - 8
A highly efficient transposon mutagenesis system for the tomato pathogen Clavibacter michiganensis subsp . michiganensis; Kirchner O et al.; A transposon mutagenesis system for Clavibacter michiganensis subsp . michiganensis was developed based on antibiotic resistance transposons that were derived from the insertion element IS1409 from Arthrobacter sp . strain TM1 NCIB12013 . As a prerequisite, the electroporation efficiency was optimized by using unmethylated DNA and treatment of the cells with glycine such that about 5 x 10(6) transformants per microg of DNA were generally obtained . Electroporation of C . michiganensis subsp . michiganensis with a suicide vector carrying transposon Tn1409C resulted in approximately 1 x 10(3) transposon mutants per pg of DNA and thus is suitable for saturation mutagenesis . Analysis of Tn1409C insertion sites suggests a random mode of transposition . Transposition of Tn1409C was also demonstrated for other subspecies of C . michiganensis.

Aust Fam Physician, 2001 Nov, 30(11), 1039 - 44
Acne . Myths and management issues; Clearihan L; BACKGROUND: Acne is one of the commonest dermatological problems, experienced by approximately 80% of Western adolescents . If left untreated it can be the source of significant physical sequelae and psychological problems . Prevalence studies show that acne is not just a problem of youth but for some, it persists into middle age . OBJECTIVE: To review both the causes of acne and current acne management issues in relation to problems and options for improving outcomes . DISCUSSION: The earlier acne is treated the more likely scarring will be minimised, so a proactive approach is important . The development of oral isotretinoin has offered those with severe, nodulocystic acne the chance of not only disease containment but suppression . However, it is still the only available treatment that targets all four pathological processes involved in acne . The development of antibiotic resistance is becoming a global problem and causing a need to revise our approach to acne.

J Antimicrob Chemother, 2002 Jan, 49(1), 161 - 4
The fate of antibiotic resistance marker genes in transgenic plant feed material fed to chickens; Chambers PA et al.; We have examined the fate of an antibiotic resistance marker, incorporated into transgenic maize when fed to chicks . Plant-derived markers were found in the crops of five birds fed transgenic maize and in the stomach contents of two birds . The plant-derived marker gene was not found in the intestines . The survival of the antibiotic resistance marker gene mirrored that of plant DNA targets, demonstrating that it survives no better than other DNA and indicating that it is very unlikely that bacteria in the gut of chickens will be transformed to ampicillin resistance when the birds are fed transgenic maize.

J Antimicrob Chemother, 2002 Jan, 49(1), 61 - 8
Emergence of macrolide and penicillin resistance among invasive pneumococcal isolates in Germany; Reinert RR et al.; Continuous nationwide surveillance of antibiotic resistance in invasive pneumococcal disease was performed in Germany between 1992 and 2000, with a total of 2586 strains being isolated . The average resistance rates to erythromycin and clindamycin were 7.7% and 3.5%, respectively, throughout the study period; 3.3% of strains were found to have intermediate resistance to penicillin . Over the study period an increase in both macrolide and penicillin resistance was observed . The percentage of strains exhibiting reduced susceptibility to penicillin increased from 1.8% in 1992 to 5.8% in 2000 . A dramatic increase in resistance was observed with erythromycin, where the resistance rate rose from 3.0% in 1992 to 15.3% in 2000 . Of the erythromycin-resistant strains, 86 (43.4%) and 111 (56.1%) belonged to the erm(B) and mef types of resistance, respectively . An analysis of macrolide consumption data during the study period showed that erythromycin resistance was highly correlated to the consumption of newer bd and od macrolides (r = 0.89, P < 0.01).

J Biol Chem, 2002 Mar 1, 277(9), 7556 - 66 Epub 2001 Dec 17.
Conjugative plasmid protein TrwB, an integral membrane type IV secretion system coupling protein . Detailed structural features and mapping of the active site cleft; Gomis-Ruth FX et al.; Bacterial conjugation is an example of macromolecular trafficking between cells and responsible for the spreading of antibiotic resistance among bacteria . It involves translocation of single-stranded DNA across membranes through a type IV secretion system . A coupling protein links the DNA-processing nucleoprotein complex, the relaxosome, with the transport apparatus during cell mating . In Escherichia coli plasmid R388 such a protein is TrwB, a basic integral inner-membrane nucleoside-triphosphate-binding protein . TrwB is the structural prototype for the type IV secretion system coupling proteins, a family of proteins essential for macromolecular transport between cells and export . The structure of a soluble TrwB variant unveils an elongated molecule with six equivalent protein units featuring a spherical quaternary structure, leaving a central channel . The structures of the non-liganded protein and four different complexes with substrate analogues and products allow the precise description of the active site architecture . The active sites are located at the interface between protomers, each of them shaped mainly by residues of one monomer, but including two crucial arginine residues belonging to the adjacent molecule . Upon substrate binding and putative hydrolysis, conformational changes are transferred from the external surface to the interior central channel.

Pediatr Infect Dis J, 2001 Sep, 20(9), 837 - 43
Pneumococcal meningitis in children: relationship of antibiotic resistance to clinical characteristics and outcomes; Buckingham SC et al.; BACKGROUND: The relationship of antibiotic susceptibility to clinical outcome in children with pneumococcal meningitis is uncertain . Previous studies have been limited by inclusion of relatively few patients infected with nonsusceptible pneumococci and inconsistent use of empiric vancomycin . METHODS: Medical records of 86 children with culture-confirmed pneumococcal meningitis at a single institution from October, 1991, to October, 1999, were retrospectively reviewed, and differences in presentation and outcome based on antibiotic susceptibility of pneumococcal isolates were assessed . RESULTS: Of 86 isolates 34 were nonsusceptible to penicillin (12 resistant) . Of 60 isolates for which cefotaxime susceptibility data were available, 17 were nonsusceptible (12 resistant) . Antibiotic susceptibility was not significantly associated with death, intensive care unit admission, mechanical ventilation, focal neurologic deficits, seizures, secondary fever, abnormal neuroimaging studies or hospital days . Children with penicillin-resistant isolates had significantly higher median blood leukocyte counts (24,100/microliter vs . 15,700/microliter, P = 0.03) and lower median CSF protein concentrations (85 mg/dl vs . 219 mg/dl, P = 0.04), were more likely to have a CSF glucose concentration of > or = 50 mg/dl (7 of 11 vs . 15 of 68, P = 0.009) and had lower rates of sensorineural hearing loss (1 of 8 vs . 25 of 40, P = 0.02) than children with isolates that were not resistant to penicillin . Children with cefotaxime-nonsusceptible isolates had an increased median duration of primary fever compared with those with nonsusceptible strains (6 days vs . 3.5 days, P = 0.02) . CONCLUSIONS: In children with pneumococcal meningitis, penicillin resistance was associated with a reduced risk of hearing loss, while cefotaxime resistance was associated with a longer duration of fever . Other outcome measures were not significantly influenced by the antibiotic susceptibility of pneumococcal isolates.

Pediatr Infect Dis J, 2001 Nov, 20(11), 1033 - 8
Twelve year observation of primary and secondary antibiotic-resistant Helicobacter pylori strains in children; Bontems P et al.; BACKGROUND: The effectiveness of Helicobacter pylori eradication regimens is influenced by antibiotic susceptibility of infecting strains . Data concerning antibiotic resistance in children are limited . We report the evolution of primary and secondary resistance in a series of Belgian children during the last 12 years . PATIENTS AND METHODS: From 1989 through 2000, H . pylori gastritis was diagnosed in 569 children, and antibiotic susceptibility tests were performed in 555 . Eradication, using different schemes, failed in 128 of 457 treated children . After eradication failure antibiotic susceptibility determination was performed in 87 of 128 . Comparison of antibiotic susceptibility of strains isolated from the gastric body and from the antrum was performed in 238 samples . RESULTS: Resistance to amoxicillin was not observed . The rate of primary resistance to nitroimidazole derivatives was 18.0% (101 of 555) and remained constant throughout this period, whereas primary resistance to macrolides increased from an average of 6.0% (range, 0 to 10%) before 1995 to 16.6% (range, 10 to 25%, P < 0.001) thereafter . Antibiotic consumption in Belgium, especially macrolides, did not show important fluctuations during the study period . Secondary resistance developed in 39 of 87 patients (46%) . Strains isolated from different gastric locations show identical susceptibility testing in all but 5 of 238 . CONCLUSIONS: Resistance of H . pylori to macrolides increased in our pediatric population which did not appear to correlate with macrolides prescription habits in our country . After eradication failure acquired secondary resistance was observed in one-half of the patients.

Hematology (Am Soc Hematol Educ Program) . 2001;:113-39.
Infections in the neutropenic patient--new views of an old problem; Donowitz GR et al.; Infection in the neutropenic patient has remained a major clinical challenge for over three decades . While diagnostic and therapeutic interventions have improved greatly during this period, increases in the number of patients with neutropenia, changes in the etiologic agents involved, and growing antibiotic resistance have continued to be problematic . The evolving etiology of infections in this patient population is reviewed by Dr . Donowitz . Presently accepted antibiotic regimens and practices are discussed, along with ongoing controversies . In Section II, Drs . Maki and Crnich discuss line-related infection, which is a major infectious source in the neutropenic . Defining true line-related bloodstream infection remains a challenge despite the fact that various methods to do so exist . Means of prevention of line related infection, diagnosis, and therapy are reviewed . Fungal infection continues to perplex the infectious disease clinician and hematologist/oncologist . Diagnosis is difficult, and many fungal infections will lead to increased mortality even with rapid diagnosis and therapy . In Section III, Dr . Pappas reviews the major fungal etiologies of infection in the neutropenic patient and the new anti-fungals that are available to treat them . Finally, Dr . Rolston reviews the possibility of outpatient management of neutropenic fever . Recognizing that neutropenics represent a heterogeneous group of patients, identification of who can be treated as an outpatient and with what antibiotics are discussed.

Mol Microbiol, 2001 Nov, 42(3), 619 - 30
Protected environments allow parallel evolution of a bacterial pathogen in a patient subjected to long-term antibiotic therapy; Low AS et al.; Long-term antibiotic treatment offers a rare opportunity to study the evolution of bacteria within the same individual . The appearance of new variants has been suggested to take place via the selection of enhanced resistance in compartments of the body in which the antibiotic concentration is low . Laboratory models of protected compartments have elegantly demonstrated their potential in selecting novel variants . However, comparable data from patients have been rare . In this study, extended antibiotic therapy in a single patient suffering from multiple infected liver cysts has provided the opportunity to observe and analyse the molecular evolution of antibiotic resistance . Each isolate has the same basic ompC gene sequence that is distinct from other Escherichia coli isolates, which suggests that they derive from the same founder population . However, the isolates differ in their auxotrophic markers, in the pI values of their dominant beta-lactamase activities and in the mutations in the promoter region of the ampC gene leading to increased expression of the AmpC enzyme . The data provide strong evidence for a single focal infection expanding via parallel pathways of evolution to give a range of antibiotic-resistant isolates . These data suggest that the infected cysts provide numerous protected environments that are the foci for the separate development of distinct variants.

Zhonghua Jie He He Hu Xi Za Zhi, 2001 Aug, 24(8), 494 - 7
{Impact of quantitative and qualitative pathogen culture on the outcome of ventilator-associated pneumonia}; Cai S et al.; OBJECTIVE: To evaluate the impact diagnostic methods with either quantitative culture (QC) or qualitative routine culture (RC) on the outcome of VAP . METHODS: A prospective, controlled clinical trial in 93 consecutive VAP episodes of 31 patients receiving mechanical ventilation was conducted . VAP episodes were randomly and crossly divided into QC (43 episodes, underwent FOB-PSB-QC) and RC group (50 episodes, underwent ETA-RC) . Empirical antibiotic treatment was given according to the attending physician and modified according to the results of culture and sensitivity . The outcomes of VAP were assessed . RESULTS: There were no differences with regard to mortality, super-infection rate, antibiotic resistance rate and cost of antibiotics when comparing QC versus RC diagnostic methods and management based on two diagnostic strategies . Inappropriate initial empirical antibiotic treatment led to a higher mortality (17.7%) when compared with those with appropriate treatment . CONCLUSION: The present study demonstrates that the outcome of VAP is probably more dependent on the adequacy of the initial antibiotic treatment than on the use of either diagnostic sampling.

BMC Clin Pharmacol . 2001;1(1):4 . Epub 2001 Nov 02.
Routine prophylactic antibiotic use in the management of snakebite; Tagwireyi DD et al.; BACKGROUND: Routine antibiotic prophylaxis following snakebite is not recommended but evidence suggests that it may be common practice in Zimbabwe . This study set out to determine and describe the extent of this practice at Parirenyatwa Hospital, a large teaching hospital in Zimbabwe METHODS: A retrospective case review (1996 to 1999 inclusive) of all cases of snakebite was undertaken at Parirenyatwa Hospital . Cases with a diagnosis of snakebite, presenting within 24 hours of the bite and with no complications or concurrent illness were defined as "routine prophylactic antibiotic use" . RESULTS: From 78 cases which satisfied the inclusion criteria, 69 (88.5%) received antibiotics . Ten different antibiotics from 6 different classes were used with penicillins the most commonly prescribed (benzylpenicillin in 29% of cases, alone or in combination) . Over 40% of antibiotics were given parenterally although all patients were conscious on admission . The total cost of antibiotics used was estimated at US$522.98 . CONCLUSION: Routine prophylactic use of antibiotics in snakebite at Parirenyatwa Hospital is common practice . This may highlight the lack of a clearly defined policy leading to wasteful inappropriate antibiotic use which is costly and may promote bacterial antibiotic resistance . Further work is required to investigate the reasons for this practice and to design appropriate interventions to counter it.

Qual Assur, 2000 Jan-Mar, 8(1), 33 - 6
Controversy over genetically modified organisms: the governing laws and regulations; Keatley KL; Genetically Modified Organisms (GMOs) are increasingly becoming a topic of controversy in the U.S . and abroad . The public is questioning their safety and wanting the products labeled as genetically modified . There are other concerns from some of the scientific world and some government officials and organizations such as the Food & Agricultural Organization (FAO) that question whether adequate research has been done to qualify GMOs as safe for long-term use . Of particular concern are the allergenic properties, a GMO may impart, possible transfer effects of antibiotic resistance (given that antibiotic resistant marker genes are used for many GMOs), the expression of previously unexpressed traits, and the drift of pollen from genetically modified crops . It has also been noted that the laws and regulations governing the biotechnology world are outdated, are not comprehensive, and span too many agencies . The primary agencies currently regulating biotechnology are the U.S . Department of Agriculture (USDA), the Food and Drug Administration (FDA), and the Environmental Protection Agency (EPA).

Antimicrob Agents Chemother, 2001 Dec, 45(12), 3279 - 86
Binding properties of a peptide derived from beta-lactamase inhibitory protein; Rudgers GW et al.; To overcome the antibiotic resistance mechanism mediated by beta-lactamases, small-molecule beta-lactamase inhibitors, such as clavulanic acid, have been used . This approach, however, has applied selective pressure for mutations that result in beta-lactamases no longer sensitive to beta-lactamase inhibitors . On the basis of the structure of beta-lactamase inhibitor protein (BLIP), novel peptide inhibitors of beta-lactamase have been constructed . BLIP is a 165-amino-acid protein that is a potent inhibitor of TEM-1 beta-lactamase (K(i) = 0.3 nM) . The cocrystal structure of TEM-1 beta-lactamase and BLIP indicates that residues 46 to 51 of BLIP make critical interactions with the active site of TEM-1 beta-lactamase . A peptide containing this six-residue region of BLIP was found to retain sufficient binding energy to interact with TEM-1 beta-lactamase . Inhibition assays with the BLIP peptide reveal that, in addition to inhibiting TEM-1 beta-lactamase, the peptide also inhibits a class A beta-lactamase and a class C beta-lactamase that are not inhibited by BLIP . The crystal structures of class A and C beta-lactamases and two penicillin-binding proteins (PBPs) reveal that the enzymes have similar three-dimensional structures in the vicinity of the active site . This similarity suggests that the BLIP peptide inhibitor may have a broad range of activity that can be used to develop novel small-molecule inhibitors of various classes of beta-lactamases and PBPs.

Quintessence Int, 2001 Oct, 32(9), 696 - 710
Amalgam--resurrection and redemption . Part 2: The medical mythology of anti-amalgam; Wahl MJ; Mercury-containing amalgam restorative material has come under attack for its alleged harmful effects on systemic health . A literature search revealed that amalgam restorations release small quantities of mercury but apparently not enough to cause systemic health problems . Mercury from dental amalgam restorations cannot be linked to kidney damage, Alzheimer's disease, multiple sclerosis, other central nervous system diseases, "amalgam disease," mental disorders, damage to the immune system, increases in antibiotic resistance, or harmful reproductive effects . Dentists occupationally exposed to mercury have not been shown to suffer harmful reproductive or other systemic health effects, provided proper mercury hygiene is used . There are legitimate health concerns about alternative restorative materials, including resin composite . According to the latest scientific information available, dental amalgam remains a safe and effective restorative material.

Int J Antimicrob Agents, 2001 Oct, 18(4), 353 - 8
Antibiotic resistance in Escherichia coli isolates obtained from animals, foods and humans in Spain; Saenz Y et al.; Antibiotic resistance was investigated in 474 Escherichia coli isolates recovered from animal faeces (broilers, pigs, pets, bulls and horses), human faeces (patients and healthy volunteers) and food products of animal origin . E . coli isolates (3260) recovered from human significant infectious samples were also included . There was a high frequency of nalidixic acid, ciprofloxacin and gentamicin resistance in E . coli isolates from broilers (88, 38 and 40%, respectively), and from foods (53, 13 and 17%) . High levels of resistance to trimethoprim-sulphamethoxazole and tetracycline have been found in E . coli isolates from broilers, pigs and foods . These data raise important questions about the potential impact of antibiotic use in animals and the possible entry of resistant pathogens into the food chain.

Eur J Gastroenterol Hepatol, 2001 Aug, 13 Suppl 2, S17 - 21
Key topics in Helicobacter pylori eradication in the management of the dyspeptic patient: a panel discussion; Kearney DJ et al.; A panel of international gastroenterologists and other specialists convened at a Takeda-sponsored symposium held during the XIIIth International Workshop on Gastroduodenal Pathology and Helicobacter pylori (October 2000, Rome) to discuss clinical management of H . pylori . Topics such as management strategies as alternatives to eradication, long-term outcomes, and the impact of antibiotic resistance to H . pylori were discussed in an interactive session . The panel concluded that 1) patients with ulcer-like or reflux-like dyspepsia do appear to benefit from proton pump inhibitor therapy, 2) eradication of H . pylori may reduce future morbidity and mortality from peptic ulcer disease and gastric carcinoma, outweighing the theoretical risk of developing gastro-oesophageal reflux disease, Barrett's oesophagus, and oesophageal adenocarcinoma, and 3) the epidemiology of resistance to H . pylori, and the impact of the percentage of eradication, should be considered when an eradication regimen is being planned for patients with non-ulcer dyspepsia . Susceptibility testing may be of help in areas where this investigation is cost effective.

Euro Surveill, 2001 Mar, 6(3), 47 - 50
Communicable disease epidemiology training in Northern Europe; Aavitsland P et al.; The five Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) have a long tradition of collaboration in communicable disease epidemiology and control . The state epidemiologists and the immunisation programme managers have met regularly to discuss common challenges and exchange experiences in surveillance and control of communicable diseases . After the three Baltic countries (Estonia, Latvia and Lithuania) regained independence in 1991 and the Soviet Union dissolved, contacts were made across the old iron curtain in several areas, such as culture, education, business, military and medicine . Each of the Nordic communicable disease surveillance institutes started projects with partners in Estonia, Latvia, Lithuania or the Russian Federation . The projects were in such diverse areas as HIV surveillance and prevention, vaccination programmes and antibiotic resistance.

Br Homeopath J, 2001 Oct, 90(4), 180 - 2
Homeopathy in acute otitis media in children: treatment effect or spontaneous resolution?
Frei H, Thurneysen A.
The conventional antibiotic treatment of acute otitis media (AOM) faces a number of problems, including antibiotic resistance . Homeopathy has been shown to be capable of treating AOM successfully . As AOM has a high rate of spontaneous resolution, a trial to prove any treatment-effect has to demonstrate very fast resolution of symptoms . The purpose of this study was to find out how many children with AOM are relieved of pain within 12 h after the beginning of homeopathic treatment, making additional measures unnecessary . Two hundred and thirty children with AOM received a first individualized homeopathic medicine in the paediatric office . If pain-reduction was not sufficient after 6 h, a second (different) homeopathic medicine was given . After a further 6 h, children who had not reached pain control were started on antibiotics . Pain control was achieved in 39% of the patients after 6 h, another 33% after 12 h . This resolution rate is 2.4 times faster than in placebo controls . There were no complications observed in the study group, and compared to conventional treatment the approach was 14% cheaper.

J Gen Intern Med, 2001 Oct, 16(10), 701 - 11
Strategies for diagnosing and treating suspected acute bacterial sinusitis: a cost-effectiveness analysis; Balk EM et al.; OBJECTIVE: Symptoms suggestive of acute bacterial sinusitis are common . Available diagnostic and treatment options generate substantial costs with uncertain benefits . We assessed the cost-effectiveness of alternative management strategies to identify the optimal approach . DESIGN: For such patients, we created a Markov model to examine four strategies: 1) no antibiotic treatment; 2) empirical antibiotic treatment; 3) clinical criteria-guided treatment; and 4) radiography-guided treatment . The model simulated a 14-day course of illness, included sinusitis prevalence, antibiotic side effects, sinusitis complications, direct and indirect costs, and symptom severity . Strategies costing less than 50,000 dollars per quality-adjusted life year gained were considered "cost-effective." MEASUREMENTS AND MAIN RESULTS: For mild or moderate disease, basing antibiotic treatment on clinical criteria was cost-effective in clinical settings where sinusitis prevalence is within the range of 15% to 93% or 3% to 63%, respectively . For severe disease, or to prevent sinusitis or antibiotic side effect symptoms, use of clinical criteria was cost-effective in settings with lower prevalence (below 51% or 44%, respectively); empirical antibiotics was cost-effective with higher prevalence . Sinus radiography-guided treatment was never cost-effective for initial treatment . CONCLUSIONS: Use of a simple set of clinical criteria to guide treatment is a cost-effective strategy in most clinical settings . Empirical antibiotics are cost-effective in certain settings; however, their use results in many unnecessary prescriptions . If this resulted in increased antibiotic resistance, costs would substantially rise and efficacy would fall . Newer, expensive antibiotics are of limited value . Additional testing is not cost-effective . Further studies are needed to find an accurate,low-cost diagnostic test for acute bacterial sinusitis.

J Bacteriol, 2001 Nov, 183(22), 6558 - 64
Complementation of a nonmotile flaB mutant of Borrelia burgdorferi by chromosomal integration of a plasmid containing a wild-type flaB allele; Sartakova ML et al.; With the recent identification of antibiotic resistance phenotypes, the use of reporter genes, the isolation of null mutants by insertional inactivation, and the development of extrachromosomal cloning vectors, genetic analysis of Borrelia burgdorferi is becoming a reality . A previously described nonmotile, rod-shaped, kanamycin-resistant B . burgdorferi flaB::Km null mutant was complemented by electroporation with the erythromycin resistance plasmid pED3 (a pGK12 derivative) containing the wild-type flaB sequence and 366 bp upstream from its initiation codon . The resulting MS17 clone possessed erythromycin and kanamycin resistance, flat-wave morphology, and microscopic and macroscopic motility . Several other electroporations with plasmids containing wild-type flaB and various lengths (198, 366, or 762 bp) of sequence upstream from the flaB gene starting codon did not lead to functional restoration of the nonmotile flaB null mutant . DNA hybridization, PCR analysis, and sequencing indicated that the wild-type flaB gene in nonmotile clones was present in the introduced extrachromosomal plasmids, while the motile MS17 clone was a merodiploid containing single tandem chromosomal copies of mutated flaB::Km and wild-type flaB with a 366-bp sequence upstream from its starting codon . Complementation was thus achieved only when wild-type flaB was inserted into the borrelial chromosome . Several possible mechanisms for the failure of complementation for extrachromosomally located flaB are discussed.

Int J Antimicrob Agents, 2001 Sep, 18(3), 295 - 8
Antibiotic resistance in hospital pathogens--acquisition or spread?
Williams JD.
Hospital resistant pathogens are a problem of hospital use allowing acquisition of multi-resistant strains . The use of antibiotics in the community and on the farm has little impact on hospital infection rates and prevalence of resistance in hospital bacteria . Once acquisition occurs the main problem is spread of clones to highly vulnerable patients . Attention to protective methods for such patients ought to be a priority in hospital infection control.

Int J Antimicrob Agents, 2001 Sep, 18(3), 287 - 90
The experience of reducing antibiotics used in animal production in the Nordic countries; Wierup M; The Nordic countries (Denmark, Finland, Norway and Sweden) have a long tradition of infectious disease control in animal production . Special attention has also been paid to the use of antibiotics . This has resulted in a relatively low use of antibiotics and also relatively favourable status of antibiotic resistance . The current situation, interventions and achievements are summarised with special reference to Sweden which was probably the first country where stringent control and prudent use of antibiotics was put into practice . The use of antibiotics for growth-promoting purposes is highlighted.

Gene, 2001 Oct 17, 277(1-2), 221 - 9
A Streptomyces rimosus aphVIII gene coding for a new type phosphotransferase provides stable antibiotic resistance to Chlamydomonas reinhardtii; Sizova I et al.; Although Chlamydomonas reinhardtii serves as the most popular algal model system, no efficient enzymatic selection marker for the nuclear transformation of wild-type cells is available . We sequenced an aminoglycoside 3'-phosphotransferase gene (aph) from Streptomyces rimosus . Though the derived protein sequence is homologous to members of APH type V, it constitutes a new type, named APHVIII . Since the aphVIII gene has a codon bias similar to that of the nuclear genome of green algae, the aphVIII coding sequence was fused to the 5'- and 3'-untranslated regions of the C . reinhardtii rbcS2 gene . C . reinhardtii transformants were capable of inactivating the antibiotics paromomycin, kanamycin, and neomycin, to which wild-type cells are sensitive . After addition of the 5'-region of hsp70A as a second promoter and insertion of the rbcS2 intron I, the transformation rate increased to two transformants per 1 x 10(5) cells, which is close to the efficiency of transforming auxotrophic strains with the homologous marker arg7 . Transformation with the promoter-less aphVIII led to random gene fusion at high frequency . In an aphVIII-based reporter gene assay we have found a so far unknown promoter activity of the 3'-untranslated region of rbcS2, that may promote antisense RNA synthesis from the rbcS2 gene in vivo . We conclude that the aphVIII gene is a useful marker for nuclear transformation and promoter tagging of C . reinhardtii wild-type and probably other green algae.

Antimicrob Agents Chemother, 2001 Nov, 45(11), 3046 - 55
Single ribosomal protein mutations in antibiotic-resistant bacteria analyzed by mass spectrometry; Wilcox SK et al.; Mutations in several ribosomal proteins are known to be related to antibiotic resistance . For several strains of Escherichia coli, the mutated protein is known but the amino acid actually altered has not been documented . Characterization of these determinants for antibiotic resistance in proteins will further the understanding of the precise mechanism of the antibiotic action as well as provide markers for resistance . Mass spectrometry can be used as a valuable tool to rapidly locate and characterize mutant proteins by using a small amount of material . We have used electrospray and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry to map out all 56 ribosomal proteins in E . coli based on intact molecular masses . We used this fingerprinting approach to locate variants of ribosomal proteins displaying a change in mass . In particular we have studied proteins responsible for streptomycin, erythromycin, and spectinomycin resistance in three strains of E . coli, and then we characterized each mutation responsible for resistance by analyzing tryptic peptides of these proteins by using MALDI-TOF and nanoelectrospray tandem mass spectrometry . The results provided markers for antibiotic resistance and demonstrated that mass spectrometry can be used to rapidly investigate changes in individual proteins from a complex with picomole amounts of protein.

Clin Infect Dis, 2001 Nov 15, 33(10), 1733 - 8 Epub 2001 Oct 05.
Preventing vascular catheter-related infections: current controversies; Farr BM; Prevention of vascular catheter-related infection remains an important priority . This review focuses on salient controversies regarding optimal preventive methods . Intensity of surveillance for nosocomial infections was the single most important predictor of prevention in the Study of the Efficacy of Nosocomial Infection Control (SENIC) . Used suboptimally by most hospitals in the SENIC study, surveillance is probably conducted even less today . There has been one randomized trial of the optimal method of aseptic insertion for central venous catheters and none comparing the 2 most frequently used sites . Scheduled replacement did not prevent infection in multiple randomized trials but, according to a recent survey, was still being used frequently . Chlorhexidine preparation of skin before and during catheterization has significantly reduced colonization of catheters in multiple randomized trials and should be used . Impregnation of catheter and/or hub surfaces with antiseptics raises less concern about fostering the development of antibiotic resistance than does the use of antibiotics for this purpose.

J Gastroenterol Hepatol, 2001 Sep, 16(9), 981 - 5
Antibiotic susceptibility of Helicobacter pylori in the Chinese population; Yakoob J et al.; AIM: To assess antibiotic susceptibility of Helicobacter pylori (H . pylori) strains to metronidazole, clarithromycin and tetracycline in the Chinese population, and to test the stability of antibiotic resistance in H . pylori 1 year after storage at -80 degrees C . METHODS: Fifty H . pylori strains isolated from patients with peptic ulcer disease were recovered from storage at -80 degrees C . Susceptibility of these strains to metronidazole, clarithromycin and tetracycline was determined by using validated disk diffusion tests, which was repeated 1 year after storage at -80 degrees C . The DNA profiles of each strain were determined by using the polymerase chain reaction-based-random amplified polymorphic DNA fingerprinting technique (PCR-RAPD) . This was repeated if any change in antibiotic susceptibility pattern was noticed . RESULTS: The resistance rate was 50% to metronidazole and 8% to clarithromycin . None of the strains was resistant to tetracycline . A dual resistance to metronidazole and clarithromycin was demonstrated in three H . pylori strains . The antibiotic susceptibility test reproduced itself in 92% (36 of 39) of the strains 1 year later; the three strains with dual resistance exhibited susceptibility to both antibiotics . Variation in antibiotic susceptibility pattern in the three H . pylori strains was associated with change in the RAPD fingerprint . CONCLUSION: The prevalence of resistance in H . pylori is high to metronidazole but low to clarithromycin in the Chinese population . The disk diffusion test appears to be a simple and reliable test, while antibiotic resistance in some H . pylori strains may disappear after long-term storage at -80 degrees C.

J Bacteriol, 2001 Oct, 183(20), 6148 - 9
Reconstruction of Escherichia coli mrcA (PBP 1a) mutants lacking multiple combinations of penicillin binding proteins; Meberg BM et al.; Previously, we constructed a set of mutants from which eight penicillin binding protein (PBP) genes were deleted in 192 combinations from Escherichia coli (S . A . Denome, P . K . Elf, T . A . Henderson, D . E . Nelson, and K . D . Young, J . Bacteriol . 181:3981-3993, 1999) . Although these mutants were constructed correctly as determined by restriction mapping and the absence of relevant protein products, we recently discovered by PCR mapping that strains from which mrcA (PBP 1a) was deleted were also missing two neighboring genes of unknown function (yrfE and yrfF) . We created a new deletion mutation in mrcA and reconstructed 63 strains lacking PBP 1a and other PBP mutant combinations . The new mrcA mutants do not exhibit mucoidy, phage resistance, temperature sensitivity, growth rate defects, or antibiotic resistance, suggesting that these phenotypes require the loss of either yrfE or yrfF alone or in combination with the absence of multiple PBPs.

Semin Respir Infect, 2001 Sep, 16(3), 203 - 9
Can guidelines for the treatment of respiratory infections lead to reduced rates of antibiotic resistance?
Niederman MS.
Guidelines have been developed for the therapy of both community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP), and, potentially, if applied appropriately, could lead to a containment or reduction in the frequency of antibiotic resistance . In the therapy of CAP, guidelines could minimize the use of excessive antibiotic therapy, and if they also improve the accuracy of therapy, they could minimize the emergence of resistant organisms in the community . However, the impact of such guidelines on resistance remains to be shown . In the near future, CAP guidelines could help contain the growing problem of quinolone-resistant pneumococci by advocating the use of the most effective of the new agents, administered at the optimal dosages . When managing HAP, the use of guidelines could improve outcome by leading to a greater percentage of patients receiving adequate empiric antibiotic therapy . It remains uncertain whether such an approach can minimize the emergence of antibiotic resistance, particularly in the intensive care unit (ICU), but it is clear that if guidelines are to be accurate, they must account for the resistance patterns that are unique to each individual hospital setting . To date, the use of computer-assisted guidelines for the therapy of nosocomial infections has been successful in minimizing the frequency of inadequate therapy, with no negative impact on antibiotic resistance . Antibiotic restriction policies have been proposed as a way to have an impact on resistance, with variable effects . In the future, antibiotic rotation is likely to be studied as a way to reduce resistance, particularly in the ICU, but a number of practical issues may limit the efficacy of such an approach .

Clin Infect Dis, 2001 Oct 15, 33(8), 1380 - 5 Epub 2001 Sep 05.
Bacterial meningitis in aging adults; Choi C; Bacterial meningitis remains a highly lethal disease in older adults, with mortality rates averaging >20% despite modern antibiotic therapy . In this population, more variable presentations are seen, with fewer patients manifesting fever, neck stiffness, and headache than among younger adults . In addition, many older adults (aged > or =60 years) may have other underlying diseases causing symptoms that may be confused with those of meningitis . The spectrum of etiologic bacterial organisms is more broad than that for a younger population, in part because of the increased frequency of severe underlying diseases and in part as a result of immunosenescence . Therapy is complicated by both the range of possible causative organisms and the increasing antibiotic resistance manifested by some . These difficulties, contrasted with the success of vaccination in the pediatric population, highlight the need for improved preventive strategies for older adults . This review outlines some key clinical points in the management of bacterial meningitis in the older adult.

Dig Dis, 2001, 19(2), 134 - 43
Helicobacter pylori therapy: first-line options and rescue regimen; Gisbert JP et al.; In the present paper, several points regarding Helicobacter pylori treatment are reviewed, with the following conclusions: (1) all different proton pump inhibitors (PPIs) are equivalent when prescribed with antibiotics; (2) ranitidine bismuth citrate is equal to or, in some cases with antibiotic resistance, more effective than PPI; (3) previous treatment with PPI does not seem to affect the rate of eradication obtained with PPI plus two antibiotics; (4) just 1 week of PPI is enough to obtain duodenal ulcer healing, provided that H . pylori eradication is achieved; (5) the eradication rates seem to be higher in peptic ulcer than in nonulcer dyspepsia; (6) in areas where the prevalence of metronidazole resistance is high, triple therapy including a PPI, clarithromycin, and amoxicillin is the best option, and (7) quadruple therapy (PPI, bismuth, tetracycline, and metronidazole) is the recommended second-line therapy after PPI-clarithromycin-amoxicillin failure, although replacing the PPI and the bismuth compound by ranitidine bismuth citrate achieves also good results .

Plant J, 2001 Aug, 27(3), 267 - 74
Chloroplast lysates support directed mutagenesis via modified DNA and chimeric RNA/DNA oligonucleotides; Kmiec EB et al.; Chimeric RNA/DNA and modified DNA oligonucleotides have been shown to direct gene-conversion events in vitro through a process involving proteins from several DNA-repair pathways . Recent experiments have extended the utility of these molecules to plants, and we previously demonstrated that plant cell-free extracts are competent to support oligonucleotide-directed genetic repair . Using this system, we are studying Arabidopsis DNA-repair mutants and the role of plant proteins in the DNA-repair process . Here we describe a method for investigating mechanisms of plastid DNA-repair pathways . Using a genetic readout system in bacteria and chimeric or modified DNA oligonucleotides designed to direct the conversion of mutations in antibiotic resistance genes, we have developed an assay for genetic repair of mutations in a spinach chloroplast lysate system . We report genetic repair of point and frameshift mutations directed by both types of modified oligonucleotides . This system enables the mechanistic study of plastid gene repair and facilitates the direct comparison between plant nuclear and organelle DNA-repair pathways.

Aust N Z J Public Health, 2001 Aug, 25(4), 371 - 5
Health and safety issues pertaining to genetically modified foods; Goodyear-Smith F; Genetic modification involves the insertion of genes from other organisms (within or between species) into host cells to select for desirable qualities . Potential benefits of GM foods include increased nutritional value; reduced allergenicity; pest and disease-resistance; and enhanced processing value . Possible detrimental outcomes include producing foods with novel toxins, allergens or reduced nutritional value, and development of antibiotic resistance or herbicide-resistant weeds . Benefits to individuals or populations need to be weighed against adverse health and environmental risks, and may differ between developing and Westernised countries . Whether testing and monitoring should exceed requirements for conventional foods is under debate . While not necessarily scientifically justifiable, consumer concerns have resulted in Australian and New Zealand requirements to label foods containing GM-produced proteins . Dissatisfied consumer advocacy groups are calling for all foods involving GM technology to be labelled, irrelevant of whether the final product contains novel protein . Goals to improve the quantity, quality and safety of foods are laudable; however, the primary aim of the bio-food industry is financial gain . GM foods may be as safe as conventional foods but public distrust runs high . It is important that discussion is informed by science and that claims of both benefits and risks are evidence-based, to ensure that the process is driven neither by the vested interest of the bio-technical multinational companies on the one hand, nor ill-informed public fears on the other.

Arch Intern Med, 2001 Aug 13-27, 161(15), 1897 - 902
Academic detailing to improve use of broad-spectrum antibiotics at an academic medical center; Solomon DH et al.; BACKGROUND: Antibiotic misuse is common and costly and may promote antibiotic resistance . We tested the efficacy of a targeted one-on-one educational program ("academic detailing") designed to improve the appropriateness of broad-spectrum antibiotic use . METHODS: A randomized controlled trial was conducted in a large US teaching hospital . During an 18-week study period, 17 general medical, oncology, and cardiology services either received academic detailing or did not . The intervention was prompted by an order for either levofloxacin or ceftazidime that led to a computer-based review of data for that patient . Orders for the 2 target antibiotics deemed unnecessary by a priori criteria were included in the study . The primary outcome examined was the number of days that unnecessary levofloxacin or ceftazidime was administered in intervention and control groups . RESULTS: Before the trial, intervention and control services had similar prescribing patterns for the target antibiotics; the drugs were used for similar indications throughout the study period . During the intervention, there was a reduction of 37% in days of unnecessary levofloxacin or ceftazidime use per 2-week interval on services randomized to the educational intervention vs control services (P< .001) . In multivariable analyses controlling for baseline prescribing and study interval, the rate of unnecessary use of the 2 target antibiotics was reduced by 41% on the intervention services compared with controls (95% confidence interval, 44%-78%; P< .001) . Length of stay, intensive care unit transfers, readmission rates, and in-hospital death rates were similar in both groups (P> or =.10 for all) . CONCLUSION: Targeted one-on-one education is a practical, effective, and safe method for reducing excessive broad-spectrum antibiotic use.

Clin Infect Dis, 2001 Sep 15, 33 Suppl 3, S193 - 205
Association between antibiotic resistance and community prescribing: a critical review of bias and confounding in published studies; Steinke D et al.; The reported association between antibiotic prescribing and resistance may be subject to bias or confounding . Bias describes any effect at any stage of investigation or inference tending to produce results that depart systematically from the true value . A confounding variable is one that is associated independently with both exposure and outcome . Confounding variables may create an apparent association or mask a real association . Pharmacoepidemiology is the study of the use and the effects of drugs in large numbers of people . We have used standard pharmacoepidemiological methods to investigate sources of bias and confounding in the association between prescribing and resistance . We conclude that the association is statistically valid and that the consistency of evidence supports a cause-effect relationship . Nonetheless, several important sources of bias and confounding must be taken into account in future studies that analyze the impact of prescribing policies on resistance.

Clin Infect Dis, 2001 Sep 15, 33 Suppl 3, S161 - 9
Minimizing potential resistance: a population dynamics view; Levin BR; I examine the results of studies that used mathematical models of the epidemiology and population genetics of antibiotic treatment and resistance in open communities and in hospitals to explore the following issues: the relationship between antibiotic consumption and the frequency of antibiotic resistance in bacterial populations in communities and in hospitals; methods of controlling the growth, dissemination, and persistence of antibiotic resistance in these settings; the extent to which resistance can be controlled; and the speed with which the effects of control measures will be realized . In open communities, it will take years or even decades to see substantial reductions in the frequency of antibiotic resistance solely as a result of more prudent (reduced) use of antibiotics . However, if we can restrict the input of resistant bacteria into hospitals, through the application of infection control and other measures, it should be possible to reduce the frequency of resistance and even eliminate resistant bacteria from these institutions in short order.

Clin Infect Dis, 2001 Sep 15, 33 Suppl 3, S138 - 46
Minimizing potential resistance: the molecular view; Courvalin P et al.; The major contribution of molecular biology to the study of antibiotic resistance has been the elucidation of nearly all biochemical mechanisms of resistance and the routes for dissemination of genetic information among bacteria . In this review, we consider the potential contribution of molecular biology to counteracting the evolution of resistant bacteria . In particular, we emphasize the fact that fundamental approaches have had direct practical effects on minimizing potential resistance: by improving interpretation of resistance phenotypes, by providing more adequate human therapy, by fostering more prudent use of antibiotics, and by allowing the rational design of new drugs that evade existing resistance mechanisms or address unexploited targets.

Clin Infect Dis, 2001 Sep 15, 33 Suppl 3, S130 - 2
Prudent use of antibiotics: are our expectations justified?
Phillips I.
Prudent use of antibiotics has 3 components, rational use, adherence to local guidelines and policies, and avoidance or reversal of upward demographic trends in antibiotic resistance . Although rational use is mandatory, it must be recognized that adherence to policies will reduce clinical freedom, for good or ill . Expectations that prudent use will deliver reversals in resistance trends should be accepted with caution . Sound, pertinent data are lacking, and our ability to detect change, if it does occur, and to attribute its cause correctly, is questionable.

Clin Infect Dis, 2001 Sep 15, 33 Suppl 3, S124 - 9
Antibiotic resistance: consequences of inaction; Levy SB; Bacterial resistance presents therapeutic dilemmas to clinicians worldwide . The warnings were there long ago, but too few people heeded them . Thus an emerging problem has grown to a crisis . Resistance is an ecological phenomenon stemming from the response of bacteria to the widespread use of antibiotics and their presence in the environment . While determining the consequences of inaction on the present and future public health, we must work to remedy the lack of action in the past . By improving antibiotic use and decreasing resistance gene frequency at the local levels, we can move towards reversing the resistance problem globally.

Chem Biol, 2001 Aug, 8(8), 791 - 800
Active site labeling of the gentamicin resistance enzyme AAC(6')-APH(2") by the lipid kinase inhibitor wortmannin; Boehr DD et al.; BACKGROUND: Aminoglycoside antibiotic resistance is largely the result of the production of enzymes that covalently modify the drugs including kinases (APHs) with structural and functional similarity to protein and lipid kinases . One of the most important aminoglycoside resistance enzymes is AAC(6')-APH(2"), a bifunctional enzyme with both aminoglycoside acetyltransferase and kinase activities . Knowledge of enzyme active site structure is important in deciphering the molecular mechanism of antibiotic resistance and here we explored active site labeling techniques to study AAC(6')-APH(2") structure and function . RESULTS: AAC(6')-APH(2") was irreversibly inactivated by wortmannin, a potent phosphatidylinositol 3-kinase inhibitor, through the covalent modification of a conserved lysine in the ATP binding pocket . 5'-{p-(Fluorosulfonyl)benzoyl}adenosine, an electrophilic ATP analogue and known inactivator of other APH enzymes such as APH(3')-IIIa, did not inactivate AAC(6')-APH(2"), and reciprocally, wortmannin did not inactivate APH(3')-IIIa . CONCLUSIONS: These distinct active site label sensitivities point to important differences in aminoglycoside kinase active site structures and suggest that design of broad range, ATP binding site-directed inhibitors against APHs will be difficult . Nonetheless, given the sensitivity of APH enzymes to both protein and lipid kinase inhibitors, potent lead inhibitors of this important resistance enzyme are likely to be found among the libraries of compounds directed against other pharmacologically important kinases.

Drug Resist Updat, 2000 Aug, 3(4), 237 - 245
The cost of antibiotic resistance from a bacterial perspective; Bjorkman J et al.; The emergence, spread and stability of antibiotic resistance in a bacterial population will be determined by several factors including (a) the volume of drug use, (b) the rate of formation of resistant mutants, (c) the biological cost of resistance and (d) the rate and extent of the genetic compensation of the costs . Generally, resistance is associated with a cost, suggesting that the frequency of resistant bacteria might decline when the use of antibiotics is decreased . However, evolution to reduce these costs, without a concomitant loss of resistance, can occur and result in a stabilization of the resistant bacteria in the population . The rate and trajectory of this compensatory evolution is dependent on the bacterial species, the specific resistance mutation and the environmental conditions under which evolution occurs .

Microbios, 2001, 106(413), 39 - 47
Microcosm studies on the persistence of peanut inoculant in acid soil and its interaction with indigenous soil micro-organisms; Rodriguez Ortega C et al.; The effect of a native peanut (Arachis hypogaea) microsymbiont strain (streptomycin resistant mutant) introduced into acid soil on the indigenous micro-organism population as well as the survival of this isolate was studied . Although the isolate survived at a fairly low population level after the 3 month period of soil incubation, it maintained its antibiotic resistance . Slight changes in the total bacteria and fungi soil populations as a result of this inoculation were also detected.

Plant J, 2001 Jul, 27(2), 161 - 70
Multiple pathways for Cre/lox-mediated recombination in plastids; Hajdukiewicz PT et al.; Plastid transformation technology involves the insertion by homologous recombination and subsequent amplification of plastid transgenes to approximately 10 000 genome copies per leaf cell . Selection of transformed genomes is achieved using a selectable antibiotic resistance marker that has no subsequent role in the transformed line . We report here a feasibility study in the model plant tobacco, to test the heterologous Cre/lox recombination system for antibiotic marker gene removal from plastids . To study its efficiency, a green fluorescent protein reporter gene activation assay was utilized that allowed visual observation of marker excision after delivery of Cre to plastids . Using a combination of in vivo fluorescence activation and molecular assays, we show that transgene excision occurs completely from all plastid genomes early in plant development . Selectable marker-free transplastomic plants are obtained in the first seed generation, indicating a potential application of the Cre/lox system in plastid transformation technology . In addition to the predicted transgene excision event, two alternative pathways of Cre-mediated recombination were also observed . In one alternative pathway, the presence of Cre in plastids stimulated homologous recombination between a 117 bp transgene expression element and its cognate sequence in the plastid genome . The other alternative pathway uncovered a plastid genome 'hot spot' of recombination composed of multiple direct repeats of a 5 bp sequence motif, which recombined with lox independent of sequence homology . Both recombination pathways result in plastid genome deletions . However, the resultant plastid mutations are silent, and their study provides the first insights into tRNA accumulation and trans-splicing events in higher plant plastids.

Protein Expr Purif, 2001 Aug, 22(3), 472 - 8
A new method for protein coexpression in Escherichia coli using two incompatible plasmids; Yang W et al.; It is commonly believed that incompatible plasmids carrying the same replicon cannot coexist stably in one Escherichia coli cell . However, we found that two incompatible plasmids carrying different antibiotic resistance genes, if under the selection pressure of the two antibiotics, can coexist in E . coli for at least 14 h, which is adequate for routine culture and protein expression . Based on this discovery, we developed a new method to coexpress foreign proteins in E . coli using two incompatible plasmids . The coding regions of the two subunits (DFF45 and DFF40) of the human DNA fragmentation factor (DFF) were cloned into two incompatible bacterial expression vectors-pET-21a with ampicillin resistance and pET-28a with kanamycin resistance, respectively . The two resulting plasmids were used to cotransform E . coli BL21(DE3) cells . After selection by ampicillin and kanamycin simultaneously, cotransformants that contain both recombinant plasmids were obtained . Induced by isopropyl beta-d-thiogalactoside, DFF45, and DFF40 were coexpressed efficiently in the presence of the two antibiotics . The coexpression product contained adequate soluble portions for both DFF45 and DFF40, while all DFF40 was insoluble if expressed alone . The coexpression product also exhibited the same caspase-activated DNase activity as its natural counterparts, which cannot be obtained if its two subunits are expressed separately .

Semin Gastrointest Dis, 2001 Jul, 12(3), 167 - 79
Treatment of Helicobacter pylori infection; Miehlke S et al.; Helicobacter pylori is a serious, chronic, progressive, and transmissible infection associated with a significant morbidity and mortality, which alone emphasizes the priority of developing adequate prophylactic or therapeutic measures . What was previously termed "asymptomatic H . pylori infection" is now recognized as a latent infection, and it is now accepted that the presence of an H . pylori infection is an indication for eradication therapy . Successful cure of H . pylori infection requires 2 or more antibiotics . Antibiotic resistance is the major impediment of cure . The ideal duration of therapy is unknown, but in general, 1 week therapy is less effective than longer durations . Compliance is important for the success of treatment; therefore, the favored regimen should have the least side effects . At present, a proton pump inhibitor (or ranitidine bismuth citrate)-clarithromycin triple therapy with either amoxicillin or metronidazole, for at least 10 days is considered first-line therapy . The alternative is quadruple therapy containing a proton pump inhibitor, bismuth, tetracycline, and a higher dose of metronidazole . Quadruple therapy is the best choice after failure of proton pump inhibitor-clarithromycin triple therapy . Confirmation of successful therapy with a urea breath test or a stool antigen test is now the standard of practice.

Evolution Int J Org Evolution, 2001 Jun, 55(6), 1110 - 22
Genetic trends in a population evolving antibiotic resistance; Walker ES et al.; The evolution of antibiotic resistance provides a well-documented, rapid, and recent example of a selection driven process that has occurred in many bacterial species . An exhaustive collection of Moraxella catarrhalis that spans a transition to chromosomally encoded penicillin resistance was used to analyze genetic changes accompanying the transition . The population was characterized by high haplotypic diversity with 148 distinct haplotypes among 372 isolates tested at three genomic regions . The power of a temporally stratified sample from a single population was highlighted by the finding of high genetic diversity throughout the transition to resistance, population numbers that remained high over time, and no evidence of departures from neutrality in the allele frequency spectra throughout the transition . The direct temporal analysis documented the persistence, antibiotic status, and haplotypic identity of strains undergoing apparent clonal expansions . Several haplotypes that were beta-lactamase nonproducers in early samples converted to producers in later years . Maintenance of genetic diversity and haplotype conversions from sensitive to resistant supported the hypothesis that penicillin resistance determinants spread to a diverse array of strains via horizontal exchange . Genetic differentiation between sample years, estimated by F(ST), was increasing at a rate that could cause complete haplotype turnover in less than 150 years . Widespread linkage disequilibrium among sites within one locus (copB) suggested recent mutation followed by clonal expansion . Nonrandom associations between haplotypes and resistance phenotypes provided further evidence of clonal expansion for some haplotypes . Nevertheless, the population structure was far from clonal as evidenced by a relatively low frequency of disequilibria both within sites at a second locus (M46) as well as between loci . The haplotype-antibiotic resistance association that was accompanied by gradual haplotype turnover is consistent with a hypothesis of genetic drift at marker loci with directional selection at the resistance locus.

Nat Struct Biol, 2001 Aug, 8(8), 710 - 4
The crystal structure of MarR, a regulator of multiple antibiotic resistance, at 2.3 A resolution; Alekshun MN et al.; MarR is a regulator of multiple antibiotic resistance in Escherichia coli . It is the prototypical member of the MarR family of regulatory proteins found in bacteria and archaea that play important roles in the development of antibiotic resistance, a global health problem . Here we describe the crystal structure of the MarR protein, determined at a resolution of 2.3 A . This is the first reported crystal structure of a member of this newly-described protein family . The structure shows MarR as a dimer with each subunit containing a winged-helix DNA binding motif.

Appl Environ Microbiol, 2001 Aug, 67(8), 3440 - 4
Laboratory-scale evidence for lightning-mediated gene transfer in soil; Demaneche S et al.; Electrical fields and current can permeabilize bacterial membranes, allowing for the penetration of naked DNA . Given that the environment is subjected to regular thunderstorms and lightning discharges that induce enormous electrical perturbations, the possibility of natural electrotransformation of bacteria was investigated . We demonstrated with soil microcosm experiments that the transformation of added bacteria could be increased locally via lightning-mediated current injection . The incorporation of three genes coding for antibiotic resistance (plasmid pBR328) into the Escherichia coli strain DH10B recipient previously added to soil was observed only after the soil had been subjected to laboratory-scale lightning . Laboratory-scale lightning had an electrical field gradient (700 versus 600 kV m(-1)) and current density (2.5 versus 12.6 kA m(-2)) similar to those of full-scale lightning . Controls handled identically except for not being subjected to lightning produced no detectable antibiotic-resistant clones . In addition, simulated storm cloud electrical fields (in the absence of current) did not produce detectable clones (transformation detection limit, 10(-9)) . Natural electrotransformation might be a mechanism involved in bacterial evolution.

Mil Med, 2001 Jul, 166(7), 581 - 6
History of respiratory illness at the U.S . Naval Academy; Gray GC et al.; Throughout history, respiratory diseases have been a frequent cause of morbidity in U.S . populations . Because of stress, crowding, and naive immune systems, military training populations are particularly prone to acute respiratory disease epidemics . An examination of the history of respiratory illness at the U.S . Naval Academy revealed that, in the earliest decades at the school, respiratory illness was a primary cause of both disease and mortality . With the advent of antibiotics and vaccines, most respiratory disease mortality has been reduced . However, even today, morbidity remains significant . Health concerns regarding respiratory diseases are heightened by emerging and reemerging respiratory disease agents that have increased antibiotic resistance and/or increased virulence . Enhanced surveillance and rapid diagnostic capabilities, placed in military settings, will increase knowledge of the epidemiology of many respiratory diseases . These strategies can lead to earlier treatment and prevention measures, thus halting the further transmission of disease and decreasing both morbidity and mortality . During the most recent history of the Naval Academy, acute respiratory infections have remained a primary cause of medical morbidity.

Biochemistry, 2001 Jul 31, 40(30), 8756 - 64
Structural analyses of nucleotide binding to an aminoglycoside phosphotransferase; Burk DL et al.; 3',5"-Aminoglycoside phosphotransferase type IIIa {APH(3')-IIIa} is a bacterial enzyme that confers resistance to a range of aminoglycoside antibiotics while exhibiting striking homology to eukaryotic protein kinases (ePK) . The structures of APH(3')-IIIa in its apoenzyme form and in complex with the nonhydrolyzable ATP analogue AMPPNP were determined to 3.2 and 2.4 A resolution, respectively . Furthermore, refinement of the previously determined ADP complex was completed . The structure of the apoenzyme revealed alternate positioning of a flexible loop (analogous to the P-loop of ePK's), occupying part of the nucleotide-binding pocket of the enzyme . Despite structural similarity to protein kinases, there was no evidence of domain movement associated with nucleotide binding . This rigidity is due to the presence of more extensive interlobe interactions in the APH(3')-IIIa structure than in the ePK's . Differences between the ADP and AMPPNP complexes are confined to the area of the nucleotide-binding pocket . The position of conserved active site residues and magnesium ions remains unchanged, but there are differences in metal coordination between the two nucleotide complexes . Comparison of the di/triphosphate binding site of APH(3')-IIIa with that of ePK's suggests that the reaction mechanism of APH(3")-IIIa and related aminoglycoside kinases will closely resemble that of eukaryotic protein kinases . However, the orientation of the adenine ring in the binding pocket differs between APH(3')-IIIa and the ePK's by a rotation of approximately 40 degrees . This alternate binding mode is likely a conserved feature among aminoglycoside kinases and could be exploited for the structure-based drug design of compounds to combat antibiotic resistance.

Biotechniques, 2001 Jul, 31(1), 204 - 10, 212
General strategy for constructing large HSV-1 plasmid vectors that co-express multiple genes; Wang X et al.; Herpes simplex virus type 1 (HSV-1) plasmid vectors have a number of attractive features for gene transfer into neurons . In particular, the large size of the HSV-1 genome suggests that HSV-1 vectors might be designed to co-express multiple genes . Here, we report a general strategy for constructing large HSV-1 plasmid vectors that co-express multiple genes . Each transcription unit is linked to an antibiotic resistance gene, and genetic selections are used to assemble large vectors . Using this strategy, we constructed large (26 or 31 kb) HSV-1 vectors that contain two transcription units and two or three genes . These vectors were efficiently packaged into HSV-1 particles using a helper virus-free packaging system . The resulting vector stocks supported the expression of two or three genes in both cultured cells and the rat brain . Potential applications of HSV-1 vectors that co-express multiple genes are discussed.

Int J Biochem Cell Biol, 2001 Sep, 33(9), 839 - 43
Structure of TrwB, a gatekeeper in bacterial conjugation; Gomis-Ruth FX et al.; Bacterial conjugation implies a trans-membrane passage of DNA, mediated by proteins encoded in conjugative plasmids . This results in a spread of genetic information, including antibiotic resistance acquisition by pathogens . Special cases of conjugation are trans-kingdom gene transfer from bacteria to plants or fungi, and even bacterial sporulation and cell division . One of the main actors in this process is an integral inner membrane DNA-binding protein, called TrwB in the E . coli R388 conjugative system . It is responsible for coupling the single-strand DNA to be transferred from the donor to the acceptor cell in its complex with other proteins, with a type IV secretion system making up the mating apparatus . The TrwB protomer consists of two domains: a nucleotide-binding domain of alpha/beta topology, similar to RecA and DNA ring helicases, and an all-alpha domain . The quaternary structure reveals an almost spherical homohexamer, strikingly similar to F(1)-ATPase . A central 20 A wide channel traverses the hexamer, thus connecting cytoplasm with periplasm.

J Am Chem Soc, 2001 Mar 21, 123(11), 2517 - 24
Electrostatics of cell membrane recognition: structure and activity of neutral and cationic rigid push-pull rods in isoelectric, anionic, and polarized lipid bilayer membranes; Sakai N et al.; Design, synthesis, and structural and functional studies of rigid-rod ionophores of different axial electrostatic asymmetry are reported . The employed design strategy emphasized presence of (a) a rigid scaffold to minimize the conformational complexity, (b) a unimolecular ion-conducting pathway to minimize the suprastructural complexity and monitor the function, (c) an extended fluorophore to monitor structure, (d) variable axial rod dipole, and (e) variable terminal charges to create axial asymmetry . Studies in isoelectric, anionic, and polarized bilayer membranes confirmed a general increase in activity of uncharged rigid push-pull rods in polarized bilayers . The similarly increased activity of cationic rigid push-pull rods with an electrostatic asymmetry comparable to that of alpha-helical bee toxin melittin (positive charge near negative axial dipole terminus) is shown by fluorescence-depth quenching experiments to originate from the stabilization of transmembrane rod orientation by the membrane potential . The reduced activity of rigid push-pull rods having an electrostatic asymmetry comparable to that in alpha-helical natural antibiotics (a positive charge near the positive axial dipole terminus) is shown by structural studies to originate from rod "ejection" by membrane potentials comparable to that found in mammalian plasma membranes . This structural evidence for cell membrane recognition by asymmetric rods is unprecedented and of possible practical importance with regard to antibiotic resistance.

Am Fam Physician, 2001 Jul 1, 64(1), 135 - 8
Should we prescribe antibiotics for acute bronchitis?
Chandran R.
OBJECTIVES: People with acute bronchitis may show little evidence of bacterial infection . If effective, antibiotics could shorten the course of the disease . However, if they are not effective, the risk of antibiotic resistance may be increased . The objective of this review was to assess the effects of antibiotic treatment in patients with a clinical diagnosis of acute bronchitis . SEARCH STRATEGY: The authors searched MEDLINE, Embase, reference lists of articles, personal collections up to 1996 and Sci-search from 1989 to 1996 . Selection CRITERIA: Randomized trials comparing any antibiotic therapy with placebo in acute bronchitis . DATA COLLECTION AND ANALYSIS: At least two reviewers extracted data and assessed trial quality . PRIMARY RESULTS: The results of eight trials involving 750 patients from eight years of age to 65 and older and including smokers and nonsmokers were included . The quality of the trials was variable . A variety of outcome measures was assessed . In many cases, only outcomes that showed a statistically significant difference between groups were reported . Overall, patients taking antibiotics had slightly better outcomes than those taking placebo . They were less likely to report feeling unwell at a follow-up visit (odds ratio, 0.42; 95 percent confidence interval {CI} 0.22 to 0.82), to show no improvement on physician assessment (odds ratio, 0.43; CI, 0.23 to 0.79) or to have abnormal lung findings (odds ratio, 0.33; CI, 0.13 to 0.86), and had a more rapid return to work or usual activities (weighted mean difference, 0.7 days earlier; CI, 0.2 to 1.3) . Antibiotic-treated patients reported significantly more adverse effects (odds ratio, 1.64; CI, 1.05 to 2.57), such as nausea, vomiting, headache, skin rash or vaginitis . REVIEWERS' CONCLUSIONS: Antibiotics appear to have a modest beneficial effect in the treatment of acute bronchitis, with a correspondingly small risk of adverse effects . The benefits of antibiotics may be overestimated in this analysis because of the tendency of published reports to include complete data only on outcomes found to be statistically significant.

Braz Dent J, 2001, 12(2), 105 - 8
Phenotypic stability and plasmid detection in Actinobacillus actinomycetemcomitans; Avila-Campos MJ et al.; The stability of hemolytic activity, antibiotic resistance and plasmid detection in Actinobacillus actinomycetemcomitans isolates were studied . These characteristics were stable for all experimental conditions . All tested isolates lost or changed some phenotypic characteristics such as colonial morphology and growth in liquid medium.

Drug Discov Today, 2001 Jul 1, 6(14), 714 - 715
Antibiotic resistance: can we beat the bugs?
Drlica K.
The Discussion Forum provides a medium for airing your views on any issues related to the pharmaceutical industry and obtaining feedback and discussion on these views from others in the field . You can discuss issues that get you hot under the collar, practical problems at the bench, recently published literature, or just something bizarre or humorous that you wish to share . Publication of letters in this section is subject to editorial discretion and company-promotional letters will be rejected immediately . Furthermore, the views provided are those of the authors and are not intended to represent the views of the companies they work for . Moreover, these views do not reflect those of Elsevier, Drug Discovery Today or its editorial team . Please submit all letters to Rebecca Lawrence, News & Features Editor, Drug Discovery Today, e-mail: Rebecca.Lawrence@drugdiscoverytoday.com

Biochem Biophys Res Commun, 2001 Jul 13, 285(2), 188 - 94
Mitochondria isolated from liver contain the essential factors required for RNA/DNA oligonucleotide-targeted gene repair; Chen Z et al.; Chimeric RNA/DNA oligonucleotides (ONs) have been used successfully for site-specific modifications of episomal and chromosomal DNA in eukaryotic cells . We explored the possibility of applying this technique to mitochondrial DNA, as single-nucleotide defects in this genome are associated with a series of human diseases . Therefore, we determined whether mitochondria possess the enzymatic machinery for chimeric ON-mediated DNA alterations . We utilized an in vitro DNA repair assay and an Escherichia coli readout system with mutagenized plasmids carrying point mutations in antibiotic resistance genes . RNA/DNA ONs were designed to correct the defects and restore kanamycin and tetracyclin resistance . Using this system, we demonstrated that extracts from highly purified rat liver mitochondria possess the essential enzymatic activity to mediate precise single-nucleotide changes . Interestingly, the frequency of gene conversion was similar in both mitochondrial and nuclear extracts, as well as from quiescent and regenerating liver . The results indicate that mitochondria contain the machinery required for repair of genomic single-point mutations, and suggest that RNA/DNA ONs may provide a novel approach to the treatment of certain mitochondrial-based diseases .

Schweiz Rundsch Med Prax, 2001 May 23, 90(21), 931 - 4
{Antibiotic resistance in respiratory tract infections: what can we do?}; Fluckiger U; The emergence of resistant bacteria is a worldwide problem . The knowledge about the local situation of resistant bacteria, the mechanisms of resistance and the judicious use of antibiotics may reduce the spread of resistant bacteria.

J Am Chem Soc, 2001 Jul 11, 123(27), 6555 - 63
Intermediate in beta-lactam hydrolysis catalyzed by a dinuclear zinc(II) complex: relevance to the mechanism of metallo-beta-lactamase; Kaminskaia NV et al.; Inactivation of beta-lactam antibiotics by metallo-beta-lactamase enzymes is a well-recognized pathway of antibiotic resistance in bacteria . As part of extensive mechanistic studies, the hydrolysis of a beta-lactam substrate nitrocefin (1) catalyzed by dinuclear zinc(II) model complexes was investigated in nonaqueous solutions . The initial step involves monodentate coordination of the nitrocefin carboxylate group to the dizinc center . The coordinated substrate is then attacked intramolecularly by the bridging hydroxide to give a novel intermediate (2') characterized by its prominent absorbance maximum at 640 nm, which affords a blue color . The NMR and IR spectroscopic data of 2' are consistent with it being zinc(II)-bound N-deprotonated hydrolyzed nitrocefin that forms from the tetrahedral intermediate upon C-N bond cleavage . Protonation of the leaving group is the rate-limiting step in DMSO solution and occurs after the C-N bond-breaking step . Addition of strong acids results in rapid conversion of 2' into hydrolyzed nitrocefin (3) . The latter can be converted back to the blue species (2') upon addition of base . The low pK(a) value for the amino group in hydrolyzed nitrocefin is explained by its involvement in extended conjugation and by coordination to zinc(II) . The blue intermediate (2') in the model system resembles well that in the enzymatic system, judging by its optical properties . The greater stability of the intermediate in the model, however, allowed its characterization by (13)C NMR and infrared, as well as electronic, spectroscopy.

J Hosp Infect, 2001 Jul, 48(3), 161 - 76
Surveillance of antibiotic resistance in European ICUs; Hanberger H et al.; Antibiotic resistance among bacteria causing hospital-acquired infections poses a threat, particularly to patients in intensive care units (ICUs) . In order to control the spread of resistant bacteria, local, regional and national resistance surveillance data must be used to develop efficient intervention strategies . In an attempt to identify national differences and the dynamics of antibiotic resistance in European ICUs, data have been merged from several networks of resistance surveillance performed during the 1990s . It should be stressed, however, that comparisons of results from different studies using different methods and different population samples must be made with caution . Antibiotic resistance across all species and drugs was, with some exceptions, highest in southern European countries and Russia, and lowest in Scandinavia . More effective strategies are needed to control the selection and spread of resistant organisms . Antibiotic intervention policies, efficient infection control measures and an overall awareness of the serious implications at public health level will contribute to the management of antibiotic resistance .

Vet Res, 2001 May-Aug, 32(3-4), 363 - 80
Molecular tools for the characterisation of antibiotic-resistant bacteria; Aarts HJ et al.; This review will discuss a number of molecular tools which are currently used as well as some innovative approaches for the characterisation of antibiotic-resistant bacterial strains . Various methods involved in the detection and characterisation of genes and mutations associated with antibiotic resistance and that are used for strain typing as part of epidemiological studies, are described . Furthermore, a few examples are discussed in which the results of both gene and strain characterisation are combined to investigate the underlying mechanism of the spread of antibiotic resistance . Some of the available molecular techniques are heavily supported by the existence of databases on the Internet . These databases either contain a fast growing amount of sequence information or a large number of allelic or fingerprint profiles . The current progress in applied DNA technology and the ongoing projects on the elucidation of the whole genomic sequence of bacterial species have lead and will further lead to the development and application of sophisticated new strategies for the analysis of antibiotic resistant bacterial strains.

Vet Res, 2001 May-Aug, 32(3-4), 243 - 59
Importance of integrons in the diffusion of resistance; Carattoli A; Horizontal transfer of resistance genes is a successful mechanism for the transmission and dissemination of multiple drug resistance among bacterial pathogens . The impact of horizontally transmitted genetic determinants in the evolution of resistance is particularly evident when resistance genes are physically associated in clusters and transferred en bloc to the recipient cell . Recent advances in the molecular characterisation of antibiotic resistance mechanisms have highlighted the existence of genetic structures . called integrons, involved in the acquisition of resistance genes . These DNA elements have frequently been reported in multi-drug resistant strains isolated from animals and humans, and are located either on the bacterial chromosome or on broad-host-range plasmids . The role of integrons in the development of multiple resistance relies on their unique capacity to cluster and express drug resistance genes . Moreover, the spread of resistance genes among different replicons and their exchange between plasmid and bacterial chromosome are facilitated by the integration of integrons into transposable elements . The association of a highly efficient gene capture and expression system, together with the capacity for vertical and horizontal transmission of resistance genes represents a powerful weapon used by bacteria to combat the assault of antibiotics.

Acta Paediatr, 2001 May, 90(5), 473 - 6
Prevention of pneumococcal disease in children . Pneumococcal conjugate vaccines: their use globally could have a major impact on public health; Kyaw MH et al.; Pneumococcal disease is a major cause of morbidity and mortality in infants and young children worldwide . New pneumococcal conjugate vaccines include 7 to 11 serotypes, which are the most common cause of paediatric disease in most parts of the world . The efficacy of a 7-valent conjugate vaccine was 97.4% (95% CI, 82.7-99.9) against invasive pneumococcal disease, and 57% (95% CI, 44-67) against otitis media, caused by vaccine serotypes . Evidence shows that the vaccine has the potential to prevent pneumonia . Pneumococcal conjugate vaccination has also been shown to reduce nasopharyngeal carriage of vaccine serotypes (particularly serotypes associated with antibiotic resistance) . Thus widespread use of pneumococcal conjugate vaccine could substantially reduce the burden of invasive disease and would have the potential to control the global spread of antibiotic resistance in pneumococci . CONCLUSION: It is important that these highly effective vaccines should be made available to children in the developing countries.

Am J Manag Care, 2001 Jun, 7(6 Suppl), S163 - 9
Challenges of managed care organizations in treating respiratory tract infections in an age of antibiotic resistance; Mogyoros M; Managing respiratory tract infections (RTIs) presents many challenges to managed care organizations (MCOs) . RTIs are among the most common illnesses treated by primary care clinicians; they seriously impact patient quality of life and are a leading cause of health-related absences from the workplace . The total direct costs of treating conditions such as acute otitis media, sinusitis, and acute exacerbations of chronic bronchitis are estimated to be $10.1 billion . The development of drug resistance has compounded these challenges by increasing treatment failures and costs and limiting treatment options . MCOs can meet these challenges by implementing clinical practice guidelines for acute respiratory infections, conducting focused studies of antibiotic use, and educating both healthcare clinicians and patients about appropriate antibiotic use.

J Clin Pharm Ther, 2001 Jun, 26(3), 195 - 9
Antibiotic prescribing by single handed general practitioners: secondary analysis of data; Gill PS et al.; AIM: To determine the contribution of various doctor and patient factors on the frequency of antibiotic prescribing . METHODS: Secondary analyses of data on 155 single handed general practitioners . RESULTS: Three variables explained 25% of variation in antibiotic prescribing . Doctors qualified from the Indian subcontinent issued more antibiotics than U.K.-qualified doctors . Patients from the non-manual social class were issued fewer antibiotics than those from the manual class and the most deprived patients received significantly more antibiotics . CONCLUSION: Very little of prescribing of antibiotics by doctors is explained by these doctor-patient factors . Prescribing is a complex process and the search for factors must continue in order to address the rising antibiotic resistance.

Aliment Pharmacol Ther, 2001 Jul, 15(7), 1023 - 9
Predictors of failure of Helicobacter pylori eradication with the standard 'Maastricht triple therapy'; Perri F et al.; BACKGROUND: Triple therapy with proton pump inhibitor, clarithromycin and amoxicillin has recently been proposed in Maastricht as first-line treatment for H . pylori infection . AIM: To determine predictors of unsuccessful eradication . METHODS: Two hundred and forty-eight patients underwent endoscopy with biopsies for rapid urease test, histology and culture with antibiotic susceptibility tests, and 13C-UBT . All infected patients were given pantoprazole (40 mg b.d.), clarithromycin (500 mg b.d.) and amoxicillin (1 g b.d.) for 1 week . Eradication was assessed by UBT at 4-6 weeks after therapy . RESULTS: One hundred and sixty-two of 248 patients (65%) were infected . Culture was positive in 144 (89%) . Prevalence rates of metronidazole, clarithromycin and amoxicillin resistance were 14, 8 and 3%, respectively . Eradication rates (95% CI) were 63% (54.7-70.6) by intention-to-treat analysis and 67% (59.4-75.4) by per protocol analysis . Drug compliance was excellent and side-effects were mild . Age > or = 45 years (OR: 2.35, CI: 1.30-4.25), smoking (OR: 1.37, CI 1.01-1.87) and high pre-treatment UBT results (OR: 1.36, CI: 1.08-1.72) were independent predictors of eradication failure . Gender, endoscopic findings, alcohol intake, and clarithromycin and amoxicillin resistance did not predict treatment failure . CONCLUSION: Despite the low prevalence of primary antibiotic resistance in our geographical area, triple therapy with pantoprazole, amoxicillin and clarithromycin achieves low eradication rates . Smoking, age and pre-treatment UBT results are predictors of potential eradication failure.

Acta Vet Hung, 2000, 48(4), 397 - 406
The pathological effect of the Bordetella dermonecrotic toxin in mice; Magyar T et al.; The effect of dermonecrotic toxin (DNT) expression of Bordetella bronchiseptica was studied in mice by comparing the pathology induced by a wild type strain with that induced by an isogenic DNT- strain in which part of the structural gene has been replaced by an antibiotic resistance cassette . While extracts of strain B58 proved toxic in intravenously inoculated mice, similar extracts from strain B58GP had lost toxic activity . The parent (B58) and the mutant (B58GP) strains of B . bronchiseptica each possessed comparable virulence for mice . These findings confirmed that DNT production was successfully abolished in strain B58GP while other virulence characteristics required for pathogenicity in mice remained intact, at a comparable level to the parent strain . Turbinate atrophy was observed in mice infected with the DNT+ strain, but not in those infected with the DNT- strain . This indicates that DNT is the cause of turbinate atrophy in the mice and not other factors produced by phase I strains of B . bronchiseptica . B . bronchiseptica DNT showed a lienotoxic effect (lymphocyte depletion and a reduction in the intensity of extramedullar haemocytopoieis) that is considered to adversely alter the immune function of the host animal . In mice infected with strain B58GP, catarrhal pneumonia with characteristic lympho-histiocytic peribronchial and perivascular infiltration was noticed . In mice infected with strain B58, large necrotic areas were seen surrounded by an inflammatory reaction . The DNT appears to directly damage lung tissues, at least in mice . DNT production seems to enhance the establishment of B . bronchiseptica in the lungs, presumably by reducing the local resistance and causing severe local damage to the lung tissues.

J Mol Biol, 2001 Jun 8, 309(3), 671 - 85
Selection, characterization and x-ray structure of anti-ampicillin single-chain Fv fragments from phage-displayed murine antibody libraries; Burmester J et al.; Single-chain Fv (scFv) antibody libraries were constructed from mice immunized with an ampicillin-bovine serum albumin conjugate . Several antibodies with specificity for intact ampicillin were selected by phage display and characterized . The antibody scFv fragment aL2 binds to intact ampicillin and shows no detectable cross-reactivity with hydrolyzed ampicillin . We determined the X-ray structures of two crystal forms of w.t . aL2, which differ mainly in the side-chain conformation of Trp H109 (according to a new consensus nomenclature Kabat residue number H95) in the extremely short (three residues) CDR H3 and the presence or absence of a well-resolved molecule of 2-methyl-pentane-2,4-diol in the bottom of the binding pocket . Attempts to co-crystallize aL2 with its antigen or to diffuse ampicillin into the wild-type aL2 crystals were unsuccessful, since crystal contacts obstruct the binding pocket . However, a mutant with two point mutations near the N terminus (Gln H6 replaced by Glu and Ala H10 (Kabat H9) replaced by Gly) crystallized in a form compatible with antigen-binding . Although the mutations affect the conformation of framework I, the conformations of the binding pocket of the uncomplexed wild-type aL2 and of the mutant complex were almost identical . The structure explains the specificity of the antibody for intact ampicillin and the degree of cross-reactivity of aL2 with a wide variety of ampicillin analogs . This antibody system will be very useful as a diagnostic reagent for antibiotics use and abuse, as a model for the effect of expression of antibiotic binding molecules in Escherichia coli, and for directed evolution towards high antibiotic resistance .

J Antimicrob Chemother, 2001 Jun, 47(6), 885 - 91
Biomaterial-associated infection of gentamicin-loaded PMMA beads in orthopaedic revision surgery; Neut D et al.; In two-stage orthopaedic revision surgery, high local levels of antibiotics are achieved after removal of an infected prosthesis through temporary implantation of gentamicin-loaded beads . However, despite their antibiotic release, these beads act as a biomaterial surface to which bacteria preferentially adhere, grow and potentially develop antibiotic resistance . Gentamicin-loaded beads were retrieved from 20 patients with prosthesis-related infections . Excised tissue samples were taken for routine culture, while beads were analysed in an extensive laboratory procedure . Extensive culture procedures indicated the presence of bacteria on gentamicin-loaded beads in 18 of the 20 patients involved, while 12 of these 18 patients were considered free of infection by routine culture . Nineteen of 28 bacterial strains isolated were gentamicin resistant and cultures from three patients yielded highly gentamicin-resistant sub-populations . It is concluded that routine culture of excised tissues in orthopaedic revision surgery is inadequate to ascertain full eradication of infection, especially as infecting, antibiotic-resistant bacteria preferentially adhere to and grow on gentamicin-loaded beads . Extensive examination of the bead surfaces is proposed as a more reliable indication that infection has been eradicated.

Am J Gastroenterol, 2001 May, 96(5), 1335 - 9
Retreatment of Helicobacter pylori infection after initial treatment failure; Kearney DJ; OBJECTIVES: Helicobacter pylori treatment regimens fail to cure the infection in at least 10-20% of patients undergoing initial treatment . Retreatment strategies for patients who have failed initial treatment for H . pylori infection remain poorly described . METHODS: The literature describing the frequency of H . pylori treatment failure and factors leading to failure is reviewed . The role of antibiotic resistance is discussed and clinical studies assessing success rates according to antibiotic resistance are described . Clinical trials evaluating the treatment success rates for a second episode of treatment are discussed . RESULTS: The literature describing retreatment of failed H . pylori infection remains limited . The existing data support the use of bismuth-based quadruple therapy or ranitidine bismuth citrate (RBC)-based triple therapy as the preferred agents after initial treatment failure . CONCLUSION: Further studies are needed to better define the optimal second treatment regimen after failed H . pylori treatment.

Ann Surg, 2001 Jun, 233(6), 859 - 66
Prospective randomized trials affect the outcomes of intraabdominal infection; Merlino JI et al.; OBJECTIVE: To compare the characteristics and outcomes of patients with intraabdominal infections enrolled in prospective randomized trials (PRTs) with those of a cohort of patients not enrolled in a trial . SUMMARY BACKGROUND DATA: Prospective randomized trials are the gold standard for the evaluation of new treatments . Patients are screened using rigorous eligibility criteria and sometimes are excluded from PRTs because of associated medical conditions or more severe illness . However, the effect that the exclusion of these patients has on the applicability of clinical trial outcomes has not been defined . METHODS: One hundred sixty-eight adults with intraabdominal infection were treated at a single institution during 7 years . Fifty-three patients were enrolled in four PRTs comparing various antibiotic regimens for treatment; 115 were not enrolled . Patient characteristics and outcomes of these two groups were compared . RESULTS: Patients with infections from appendicitis (n = 68) had a low severity of illness and similar outcomes in both groups . These patients and those for whom a concurrent PRT was unavailable were excluded from subsequent analysis . Eighty-eight patients (42 PRT, 46 not enrolled) with serious infection remained for analysis . Patients enrolled in PRTs were younger, had less severe illness, had a decreased length of stay, a lower incidence of antibiotic resistance, and less frequent extraabdominal infections than those not enrolled in a trial . Patients enrolled in PRTs were more likely to be cured and were less likely to die . Logistic regression analysis demonstrated that cure was associated with a lower initial severity of illness, absence of antibiotic resistance, and participation in a PRT . CONCLUSIONS: Patients with intraabdominal infection enrolled in PRTs have an increased likelihood of cure and survival . This is due in part to a lower incidence of antibiotic resistance, which may reflect improved drug selection . Patients not enrolled in PRTs are at greater risk for treatment failure and death because of concomitant illness . Outcomes from PRTs may not be applicable to all patients with intraabdominal infections.

FEMS Microbiol Lett, 2001 May 15, 199(1), 15 - 20
Inhibition of sporulation, glycopeptide antibiotic production and resistance in Streptomyces toyocaensis NRRL 15009 by protein kinase inhibitors; Neu JM et al.; Production of the glycopeptide antibiotic A47934 by Streptomyces toyocaensis NRRL 15009 begins in the late exponential phase in liquid culture and peaks in the early stationary phase . The pattern of cellular phosphoprotein production changes upon onset of A48934 production with the appearance of several novel phosphoproteins only when an antibiotic is being produced . Phosphoamino acid analysis revealed that S . toyocaensis NRRL 15009 produces proteins phosphorylated on His, Ser, Thr and Tyr, with most being membrane-associated . Addition of the isoflavones genistein or quercetin abolishes A47934 production in liquid culture and sporulation on solid medium . Furthermore, genistein slows the onset of inducible glycopeptide antibiotic resistance in S . toyocaensis NRRL 15009 . These results support the participation of protein kinase pathways in A47934 biosynthesis and resistance and cell differentiation in S . toyocaensis NRRL 15009.

Antimicrob Agents Chemother, 2001 Jun, 45(6), 1879 - 81
Expression of multidrug efflux pump SmeDEF by clinical isolates of Stenotrophomonas maltophilia; Alonso A et al.; The presence of the multidrug efflux pump SmeDEF was assessed in a collection of clinical isolates of Stenotrophomonas maltophilia . All isolates encoded this pump, as demonstrated by PCR . Forty-seven percent of the strains overproduced a protein of the same size that was immunoreactive against an anti-SmeF antibody, and 33% overexpressed the gene semD when they were tested by reverse transcription-PCR . A correlation between smeDEF overexpression and antibiotic resistance was observed.

Planta, 2001 Apr, 212(5-6), 851 - 7
Insertion of polydeoxyadenosine-rich sequences into an intergenic region increases transcription in Chlamydomonas reinhardtii chloroplasts; Lisitsky I et al.; In this study, chloroplast transformation in Chlamydomonas reinhardtii was used to insert a tract of polydeoxyadenosine, which is known to influence DNA structure and transcription in other systems, between the 3' end of the atpB gene, encoding the beta-subunit of the chloroplast ATP synthase, and a downstream chimeric gene, aadA, encoding antibiotic resistance . Run-on transcription and RNA analyses revealed that in cells containing (dA)40 and (dAAAGGG)8, aadA was transcribed at a higher rate, and its RNA accumulated to a relatively high level . It is concluded that poly(dA/dT) can function in the chloroplast as a transcription enhancer element . Therefore, the insertion of poly(dA/dT) sequence into the intergenic region of a multicistronic transcription unit may modulate gene expression at the transcriptional level.

J Virol Methods, 2001 May, 94(1-2), 155 - 62
A quantitative assay for measuring human foamy virus using an established indicator cell line; Tai HY et al.; In order to improve the accuracy for detecting human foamy virus (HFV), an indicator cell line was established by co-transfecting baby hamster kidney-21 cells with two plasmids: one containing a G418 antibiotic resistance marker and the other including the luc gene which was placed downstream of the inducible HFV long terminal repeat promoter (from -533 to +20) . Among 11 independent subclones, IdB14 was found to be stable with a low basal level of luciferase activity . Although the changes in luciferase activity in infected clones showed time-dependency and peaked at day 8, it is possible to differentiate infected and uninfected cells on day 2 . The sensitivity of the foamy virus activated luciferase (FAL) assay was 400 times higher than the end-point syncytium formation by TCID(50) . The HFV LTR promoter in the IdB14 cell line was specific for this virus . Moreover, a linear relationship was found between the MOI and the activated intensity of luciferase expression . These findings suggest that the FAL assay using the IdB14 indicator cell line is a simple and useful technique for rapid diagnosis and quantitation of active HFV infection.

FEMS Microbiol Lett, 2001 Apr 20, 198(1), 15 - 6
PCR detection of Helicobacter pylori in string-absorbed gastric juice; Dominguez-Bello MG et al.; Molecular methods for detection of Helicobacter pylori infection have been shown to be highly sensitive in gastric biopsies and cultures . The objective of this work was to compare PCR detection of H . pylori DNA in string-absorbed gastric juice and in gastric biopsies . The study was performed in 47 dyspeptic adult patients undergoing endoscopy, and infection was detected by amplification of a segment of H . pylori ureA gene . Of the 29 patients positive in biopsy analysis, 23 (79%) were also positive in the gastric string . PCR analysis of gastric strings is a sensitive and safe procedure to detect H . pylori when endoscopy is not indicated, and may be of great clinical and epidemiological usefulness in determining effectiveness of eradication therapies, typing virulence genes and detecting antibiotic resistance mutations.

Arch Dis Child, 2001 May, 84(5), 419 - 22
Antibiotic resistance and antibiotic sensitivity based treatment in Helicobacter pylori infection: advantages and outcome; Street ME et al.; AIMS: To compare two strategies for the eradication of Helicobacter pylori infection . METHODS: Groups 1 and 2 each consisted of 75 consecutive patients . Patients in group 1 were treated with two antibiotics based on antibiotic susceptibility testing; those in group 2 received amoxycillin and clarithromycin for eight days, together with either ranitidine or omeprazole . Eradication rate was assessed in both groups six months after treatment . RESULTS: In group 1, H pylori grew in culture in 63/75 cases . Susceptibility testing showed that 35/63 isolates were resistant to metronidazole, 10/63 to clarithromycin, 2/63 to ampicillin, 1/63 to tetracycline, and 5/63 to both clarithromycin and metronidazole . In group 1 the infection was eradicated in 96% of the initial 75 subjects, and in 98% of the subjects treated according to the antibiotic assay (62/63) . As two patients were lost at follow up the overall eradication rate was 99% . In group 2, eradication was achieved in 61/75 subjects (81%) . This was significantly lower than the percentage of eradication observed in group 1 (81% versus 99%) . CONCLUSIONS: Antibiotic susceptibility tests are useful in childhood as a very high percentage of subjects are cured . This approach is costly, but selective antibiotic treatment contributes to limit further development of antibiotic resistance, and money is saved in terms of reinvestigation and further repeated treatments.

Rinsho Byori, 2001 Feb, 49(2), 126 - 9
{New evidence for detecting Helicobacter pylori in clinics}; Hoshina S et al.; A part of diagnostic tests for Helicobacter pylori was approved as National Health Insurance system in Ministry of Health and Welfare Japan on last November 2000 . The gold standard for the presence of most infectious diseases is successful culture of the organism . H . pylori is fastidious and time consuming for growth in media . Instead of bacterial culture of H . pylori from biopsy sample, we need to effort to develop rapid methods to identify gene segment of H . pylori and its antibiotic resistance . Even the genetic methods would be developed, circular antigen product of H . pylori must be important for diagnosis of its clinical pathology . Here we listed the available diagnostic tests for histology, bacterial culture, rapid urease test, urea breath testing, and serological testing for H . pylori in Japan.

Br J Neurosurg, 2001 Feb, 15(1), 57 - 62
Management of brain stem abscess; Fuentes S et al.; The brain stem is an uncommon site of a brain abscess . Such lesions were invariably fatal before 1974, when the arrival of computed tomography and magnetic resonance imaging improved the prognosis . This new case with a good result shows the usefulness of early diagnosis, careful clinical and radiological monitoring and combined medical and surgical management . A child 2 1/2 years of age was admitted to the department of neurosurgery for diagnosis and treatment of a brain stem lesion . The clinical context and discovery of an intrabronchial foreign body, as well as neuroradiological investigations, suggested a diagnosis of brain stem abscess . Initial treatment with broad spectrum antibiotics with good cerebral penetration was associated with an increase in the size of the abscess and clinical worsening . Stereotactic aspiration of lesion was performed by a transpeduncular approach under CT guidance and general anaesthesia . Secondary thoracotomy enabled removal of an intrabronchial needle . After evacuation, in spite of failure to identify the organism, neurological deficit resolved rapidly and the lesion no longer appeared on CT . Management of a brain abscess always includes antibiotics . They must cover the organisms most often encountered in brain abscesses and have good cerebral penetration . Medical treatment seems to suffice for small abscesses . A brain stem abscess with rapid clinical signs, together with current neuroradiogical diagnostic techniques, enables early discovery of such abscesses when they are still small . Treatment of brain stem abscesses includes primary antibiotic therapy, then stereotaxic drainage when there is any diagnostic doubt, poor clinical tolerability or antibiotic resistance.

Physician Exec, 2001 Mar-Apr, 27(2), 86 - 7
Public health infrastructure: creating a solid foundation; Benjamin GC; The nation's public health system remains in disarray, despite the 1988 warning by the Institute of Medicine in its landmark report, "The Future of Public Health." Recent concerns about antibiotic resistance, inadequate disease surveillance capabilities, bioterrorism, and an increasing need for training the public health workforce have brought this problem into the forefront of congressional concern . Recent legislation aimed at addressing this problem was passed last Fall and signed into law . This program will take a significant step towards ensuring a solid public health system when it is fully implemented.

Aliment Pharmacol Ther, 2001 Apr, 15(4), 513 - 8
Nitrofurantoin quadruple therapy for Helicobacter pylori infection: effect of metronidazole resistance; Graham DY et al.; BACKGROUND: Antibiotic resistance has increasingly been recognized as the major cause of treatment failure for Helicobacter pylori infection . New therapies for patients with metronidazole- or clarithromycin-resistant H . pylori are needed . AIM: To investigate the role of nitrofurantoin quadruple therapy for the treatment of H . pylori . METHODS: Patients with confirmed H . pylori infection received nitrofurantoin (100 mg t.d.s.), omeprazole (20 mg b.d.), Pepto-Bismol (two tablets t.d.s.), and tetracycline (500 mg t.d.s.) for 14 days . Four or more weeks after the end of therapy, outcome was assessed by repeat endoscopy with histology and culture or urea breath testing . RESULTS: Thirty patients were entered, including 25 men and five women; the mean age was 54.9 years . The most common diagnoses were duodenal ulcer (23%) and GERD (18%) . The intention-to-treat cure rate was 70% (95% CI: 50.6-85%) . Nitrofurantoin quadruple therapy was more effective with metronidazole-sensitive strains (88%; 15 out of 17) than with metronidazole-resistant strains (33%; three out of nine; P=0.008) . Two of the treatment failures had pre-treatment isolates susceptible to metronidazole, which were resistant after therapy . CONCLUSIONS: Because nitrofurantoin quadruple therapy performed inadequately in the presence of metronidazole resistance, we conclude that nitrofurantoin is unlikely to find clinical utility for the eradication of H . pylori.

Int J Antimicrob Agents, 2001 Mar, 17(3), 171 - 6
Antibiotic resistance in the absence of selective pressure; Gillespie SH; Antibiotic resistance poses a serious threat to modern medical practice making treatment more difficult and is associated with increased mortality among patients infected with resistant organisms . There is clear evidence that acquisition of resistance is associated with a decrease in the fitness of the organisms at least in the short term . Evidence from in vitro experiments indicates that bacteria have the ability to adapt to this deficit and recover fitness on serial passage . More recent results show that identical organisms isolated from patients in outbreaks have an initial deficit but that adaptation occurs in vivo . Strategies directed towards controlling resistance must move beyond wishful thinking that supposes that these organisms will disappear merely with control of prescribing . In some cases, resistance will not disappear because there is no evolutionary disadvantage in being resistant once adaptation has taken place . It is important, therefore, that we direct our efforts towards preventing primary resistance emerging and in limiting the spread of resistant strains . Ultimately, we must look again to new drug discovery to improve our therapeutic armoury.

J Biol Chem, 2001 Jun 29, 276(26), 23929 - 36 Epub 2001 Feb 27.
Molecular mechanism of aminoglycoside antibiotic kinase APH(3')-IIIa: roles of conserved active site residues; Boehr DD et al.; The aminoglycoside antibiotic kinases (APHs) constitute a clinically important group of antibiotic resistance enzymes . APHs share structural and functional homology with Ser/Thr and Tyr kinases, yet only five amino acids are invariant between the two groups of enzymes and these residues are all located within the nucleotide binding regions of the proteins . We have performed site-directed mutagenesis on all five conserved residues in the aminoglycoside kinase APH(3')-IIIa: Lys(44) and Glu(60) involved in ATP capture, a putative active site base required for deprotonating the incoming aminoglycoside hydroxyl group Asp(190), and the Mg(2+) ligands Asn(195) and Glu(208), which coordinate two Mg(2+) ions, Mg1 and Mg2 . Previous structural and mutagenesis evidence have demonstrated that Lys(44) interacts directly with the phosphate groups of ATP; mutagenesis of invariant Glu(60), which forms a salt bridge with the epsilon-amino group of Lys(44), demonstrated that this residue does not play a critical role in ATP recognition or catalysis . Results of mutagenesis of Asp(190) were consistent with a role in proper positioning of the aminoglycoside hydroxyl during phosphoryl transfer but not as a general base . The Mg1 and Mg2 ligand Asp(208) was found to be absolutely required for enzyme activity and the Mg2 ligand Asn(195) is important for Mg.ATP recognition . The mutagenesis results together with solvent isotope, solvent viscosity, and divalent cation requirements are consistent with a dissociative mechanism of phosphoryl transfer where initial substrate deprotonation is not essential for phosphate transfer and where Mg2 and Asp(208) likely play a critical role in stabilization of a metaphosphate-like transition state . These results lay the foundation for the synthesis of transition state mimics that could reverse aminoglycoside antibiotic resistance in vivo.

Microsc Res Tech, 2001 Mar 15, 52(6), 766 - 77
Tracking oligodendrocytes during development and regeneration; Chandross KJ et al.; Over the past decade, advances in strategies to tag cells have opened new avenues for examining the development of myelin-forming glial cells and for monitoring transplanted cells in animal models of myelin insufficiency . The strategies for labelling glial cells have encompassed a range of genetic modifications as well as methods for directly attaching labels to cells . Genetically modified oligodendrocytes have been engineered to express enzymatic (e.g., beta-galactosidase, alkaline phosphatase), naturally fluorescent (e.g., green fluorescent protein), and antibiotic resistance (e.g., neomycin, zeomycin) reporters . Genes have been introduced in vivo and in vitro with viral or plasmid vectors to somatically label glial cells . To generate germ-line transmission of tagged oligodendrocytes, transgenic mice have been created both by direct injection into mouse fertilized eggs and by "knock-in" of reporters targetted to myelin gene loci in embryonic stem cells . Each experimental approach has advantages and limitations that need to be considered for individual applications . The availability of tagged glial cells has expanded our basic understanding of how oligodendrocytes are specified from stem cells and should continue to fill in the gaps in our understanding of how oligodendrocytes differentiate, myelinate, and maintain their myelin sheaths . Moreover, the ability to select oligodendrocytes by virtue of their acquired antibiotic resistance has provided an important new tool for isolating and purifying oligodendrocytes . Tagged glial cells have also been invaluable in evaluating cell transplant therapies in the nervous system . The tracking technologies that have driven these advances in glial cell biology are continuing to evolve and present new opportunities for examining oligodendrocytes in living systems . Microsc . Res . Tech . 52:766-777, 2001 . Published 2001 Wiley-Liss, Inc.

J Bacteriol, 2001 Apr, 183(8), 2667 - 71
Twelve-transmembrane-segment (TMS) version (DeltaTMS VII-VIII) of the 14-TMS Tet(L) antibiotic resistance protein retains monovalent cation transport modes but lacks tetracycline efflux capacity; Jin J et al.; A "Tet(L)-12" version of Tet(L), a tetracycline efflux protein with 14 transmembrane segments (TMS), was constructed by deletion of two central TMS . Tet(L)-12 catalyzed Na+/H+ antiport and antiport with K+ as a coupling ion as well as or better than wild-type Tet(L) but exhibited no tetracycline-Me2+/H+ antiport in Escherichia coli vesicles.

J Antimicrob Chemother, 2001 Apr, 47(4), 459 - 61
Analysis of metronidazole, clarithromycin and tetracycline resistance of Helicobacter pylori isolates from Korea; Kim JJ et al.; Antibiotic resistance in Helicobacter pylori varies according to geographical region . We studied the primary resistance rates among 652 H . pylori isolated from Korea in relation to collection date, disease presentation, age and gender . Resistance rates were 40.6% (metronidazole), 5.9% (clarithromycin), 5.3% (tetracycline), 0% (amoxycillin), 1.5% (furazolidone) and 1.5% (nitrofurantoin) . Resistance to metronidazole and clarithromycin increased from 1994 to 1999 (from 33.3 to 47.7% and 4.8 to 7.7%, respectively), but the differences only reached significance when rates of metronidazole resistance in women were compared with those in men (48.6 versus 36.9%).

Clin Infect Dis, 2001 Apr 1, 32(7), 1055 - 61 Epub 2001 Mar 21.
Methodological principles of case-control studies that analyzed risk factors for antibiotic resistance: a systematic review; Harris AD et al.; Case-control studies that analyze the risk factors for antibiotic-resistant organisms have varied epidemiological methodologies, which may lead to biased estimates of antibiotic risk factors . A systematic review of case-control studies that analyzed risk factors for antibiotic-resistant organisms addressed 3 methodological principles: method of control group selection, adjustment for time at risk, and adjustment for comorbid illness . A total of 406 abstracts were reviewed . Thirty-seven studies met the inclusion and exclusion criteria and were reviewed and evaluated for the 3 methodological principles . Thirteen (35%) of 37 studies chose the preferred control group . Eleven adjusted for time at risk . Twenty-seven adjusted for comorbid illness . Future studies need to consider more closely the optimization of control group selection, adjusting for confounding caused by time at risk, and adjusting for confounding caused by comorbid illness.

Presse Med, 2001 Jan, Spec No 1, 7 - 10
{Pneumococcal antibiotic resistance . Results from 21 regional registries for 1999}; Vergnaud M et al.; IN ADULTS: The prevalence of reduced susceptibility to penicillin was an estimated 40% with rates of 23% for amoxicillin and 15% for cefotaxime . For resistant strains, the rates were 11% for penicillin, 1.3% for amoxicillin and 0.3% for cefotaxime . For respiratory tract samples grouped together, pneumococcal resistance to antibiotics, erythromycin excepted, has increased little in France since 1997 . For lung samples, beta-lactam activity has remained stable with only rare strains exhibiting amoxicillin and cefotaxime resistance . IN CHILDREN: The prevalence of reduced susceptibility to penicillin was 53%, 32% for amoxicillin and 22% for cefotaxime . Despite a high rate of penicillin-G resistant strains (16%), amoxicillin and cefotaxime resistant strains remain rare, 2.8% and 1.2% respectively . For all samples grouped together, pneumococcal resistance to antibiotics, erythromycin excepted, has increased little in France since 1997 . There has however been an alarming rise in resistance of strains isolated from blood cultures . Globally, beta-lactam activity has remained stable and only rare amoxicillin and cefotaxime resistant strains have been isolated, including middle ear fluid sample . SEROTYPE DISTRIBUTION: Among the strains with reduced susceptibility to penicillin isolated in 1999, the more frequent serotypes were serotypes 6, 9, 14, 15, 19 or 23.

Presse Med, 2001 Jan, Spec No 1, 11 - 2, 15-20
{Pneumococcal antibiotic resistance . Data from 6 regional registries for 1999}; Donnio PY et al.; RESISTANCE BY REGION: Resistance varied greatly by region, ranging from 34.2% resistant strains in Alsace to 63.1% in Brittany . The incidence of resistant strains was always higher in children (especially in children aged 1 to 5 years) and in ENT samples . The time course of resistance has varied between regions, as has that of serotypes . CRUCIAL FINDING: In these 6 regions, and despite a high incidence (that varied from one region to another) of reduced susceptibility strains for penicillin G, amoxicillin (19-32%) and cefotaxime (6.5-18.5%), amoxicillin-cefotaxime resistant strains remained very rare (0.2-3.5%).

Microbiology, 2001 Mar, 147(Pt 3), 527 - 33
Phenotypic consequences of red-white colony type variation in Mycobacterium avium; Cangelosi GA et al.; Mycobacterium avium undergoes reversible morphotypic switching between the virulent transparent colony type and the less virulent opaque colony type . A new morphotypic switch in M . avium, termed red-white, that becomes visible when opaque colonies of clinical isolates are grown on agar media containing Congo red, was recently described . White opaque (WO) variants were found to be more resistant to multiple antibiotics than were red opaque (RO) variants . The present paper reports that transparent derivatives of RO and WO clones retain the differential Congo red binding properties of their opaque parents, indicating that the opaque-transparent switch operates independently of the red-white switch . White transparent variants were more resistant to clarithromycin and rifampin in vitro, and better able to survive within human macrophages, than their red transparent counterparts . Neither red nor white variants were markedly favoured during growth in vitro; however, red variants were better able to spread on soft agar (sliding motility), a potential selective advantage under some environmental circumstances . White-to-red switching was frequently observed in vitro and was accompanied by decreased antibiotic resistance and increased motility . Red-to-white switching has yet to be observed in vitro, indicating that the red morphotype is very stable . Significantly, some widely studied laboratory reference strains of M . avium, including strain 2151 and the genome sequence strain 104, are stable red clones . These strains are intrinsically antibiotic resistant and virulent in animal models, but they may not express genes encoding the elevated levels of antibiotic resistance and intracellular survival observed in white variants.

Mol Gen Mikrobiol Virusol, 2001, (1), 3 - 12
{Structural organization and mechanisms of mobility of the gene cassette coding for resistance to antibiotics and bacterial virulence factors}; Il'ina TS; The review is focussed on two types of gene cassettes which are significant in bacterial variability . The first type are cassettes with antibiotic resistance genes; these are the smallest mobile genetic elements including a gene (most commonly an antibiotic resistance gene) and a short sequence acting as a recombination site . Sometimes these cassettes contain genes not responsible for antibiotic resistance but their functions are not yet known . The second type contains large clusters of genes coding for bacterial virulence factors . They were termed "pathogenicity islands" due to their difference in the percentage of G-C pairs in comparison with bacterial chromosomes, in which they are contained . The structural organization and mechanisms of mobility of various types of gene cassettes are discussed.

EMBO J, 2001 Mar 1, 20(5), 1184 - 91
Regulated phase transitions of bacterial chromatin: a non-enzymatic pathway for generic DNA protection; Frenkiel-Krispin D et al.; The enhanced stress resistance exhibited by starved bacteria represents a central facet of virulence, since nutrient depletion is regularly encountered by pathogens in their natural in vivo and ex vivo environments . Here we explore the notion that the regular stress responses, which are mediated by enzymatically catalyzed chemical transactions and promote endurance during the logarithmic growth phase, can no longer be effectively induced during starvation . We show that survival of bacteria in nutrient-depleted habitats is promoted by a novel strategy: finely tuned and fully reversible intracellular phase transitions . These non-enzymatic transactions, detected and studied in bacteria as well as in defined in vitro systems, result in DNA sequestration and generic protection within tightly packed and highly ordered assemblies . Since this physical mode of defense is uniquely independent of enzymatic activity or de novo protein synthesis, and consequently does not require energy consumption, it promotes virulence by enabling long-term bacterial endurance and enhancing antibiotic resistance in adverse habitats.

Nat Struct Biol, 2001 Mar, 8(3), 238 - 42
Predicting the emergence of antibiotic resistance by directed evolution and structural analysis; Orencia MC et al.; Directed evolution can be a powerful tool to predict antibiotic resistance . Resistance involves the accumulation of mutations beneficial to the pathogen while maintaining residue interactions and core packing that are critical for preserving function . The constraint of maintaining stability, while increasing activity, drastically reduces the number of possible mutational combination pathways . To test this theory, TEM-1 beta-lactamase was evolved using a hypermutator E . coli-based directed evolution technique with cefotaxime selection . The selected mutants were compared to two previous directed evolution studies and a database of clinical isolates . In all cases, evolution resulted in the generation of the E104K/M182T/G238S combination of mutations ( approximately 500-fold increased resistance), which is equivalent to clinical isolate TEM-52 . The structure of TEM-52 was determined to 2.4 A . G238S widens access to the active site by 2.8 A whereas E104K stabilizes the reorganized topology . The M182T mutation is located 17 A from the active site and appears to be a global suppressor mutation that acts to stabilize the new enzyme structure . Our results demonstrate that directed evolution coupled with structural analysis can be used to predict future mutations that lead to increased antibiotic resistance.

Nucleic Acids Res . 2001 Mar 1;29(5):E26.
Escherichia coli strains that allow antibiotic-free plasmid selection and maintenance by repressor titration; Cranenburgh RM et al.; We report the construction of two novel Escherichia coli strains (DH1lacdapD and DH1lacP2dapD) that facilitate the antibiotic-free selection and stable maintenance of recombinant plasmids in complex media . They contain the essential chromosomal gene, dapD, under the control of the lac operator/promoter . Unless supplemented with IPTG (which induces expression of dapD) or DAP, these cells lyse . However, when the strains are transformed with a multicopy plasmid containing the lac operator, the operator competitively titrates the LacI repressor and allows expression of dapD from the lac promoter . Thus transformants can be isolated and propagated simply by their ability to grow on any medium by repressor titration selection . No antibiotic resistance genes or other protein expressing sequences are required on the plasmid, and antibiotics are not necessary for plasmid selection, making these strains a valuable tool for therapeutic DNA and recombinant protein production . We describe the construction of these strains and demonstrate plasmid selection and maintenance by repressor titration, using the new pORT plasmid vectors designed to facilitate recombinant DNA exploitation.

J Bacteriol, 2001 Mar, 183(6), 2025 - 31
Identification of the varR gene as a transcriptional regulator of virginiamycin S resistance in Streptomyces virginiae; Namwat W et al.; A gene designated varR (for virginiae antibiotic resistance regulator) was identified in Streptomyces virginiae 89 bp downstream of a varS gene encoding a virginiamycin S (VS)-specific transporter . The deduced varR product showed high homology to repressors of the TetR family with a conserved helix-turn-helix DNA binding motif . Purified recombinant VarR protein was present as a dimer in vitro and showed clear DNA binding activity toward the varS promoter region . This binding was abolished by the presence of VS, suggesting that VarR regulates transcription of varS in a VS-dependent manner . Northern blot analysis revealed that varR was cotranscribed with upstream varS as a 2.4-kb transcript and that VS acted as an inducer of bicistronic transcription . Deletion analysis of the varS promoter region clarified two adjacent VarR binding sites in the varS promoter.

Dis Manag Advis, 2001 Jan, 7(1), 13 - 6, 1
Patient, provider education targeted in efforts to curb antibiotic resistance; The chronic obstructive pulmonary disease exacerbation; Division of Respirology, Department of Respiratory Medicine, University of Western Ontario, London, CanadaChronic obstructive pulmonary disease is the only leading cause of death with a rising prevalence . The medical and economic costs arising from acute exacerbations of COPD are therefore expected to increase over the coming years . Although exacerbations may be initiated by multiple factors, the most common identifiable associations are with bacterial and viral infections . These are associated with approximately 50% to 70% and 20% to 30% of COPD exacerbations, respectively . In addition to smoking cessation, annual influenza vaccination is the most important method for preventing exacerbations . Controlled O2 is the most important intervention for patients with acute hypoxic respiratory failure . Evidence from randomized, controlled trials justifies the use of corticosteroids, bronchodilators (but not theophylline), noninvasive positive-pressure ventilation (in selected patients), and antibiotics, particularly for severe exacerbations . Antibiotics should be chosen according to the patient's risk for treatment failure and the potential for antibiotic resistance . In the acute setting, combined treatment with beta-agonist and anticholinergic bronchodilators is reasonable but not supported by randomized controlled studies . Physicians should identify and, when possible, correct malnutrition . Chest physiotherapy has no proven role in the management of acute exacerbations.

Med J Aust, 2000 Nov 20, 173(10), 521 - 3
Antibiotic resistance in Helicobacter pylori; Mollison LC et al.; OBJECTIVE: To describe antibiotic resistance patterns in Helicobacter pylori . DESIGN: Culture and antibiotic sensitivity testing of antral and gastric body biopsy samples from patients having gastroscopy . PARTICIPANTS: Consecutive consenting patients aged 18 years or more presenting for gastroscopy from 1 July 1998 to 30 June 1999 . Setting: An open-access gastroscopy service at an urban university tertiary hospital . MAIN OUTCOME MEASURES: Number of H . pylori isolates showing resistance to antibiotics; correlates of such resistance with demographic and clinical information . RESULTS: Of 1580 patients undergoing endoscopy, 434 agreed to participate in the study . 108 (24.9%) had positive cultures for H . pylori, and 88 of these isolates (81%) were available for further testing . Resistance to metronidazole and clarithromycin was detected in 36% and 11%, respectively . No resistance was found to tetracycline or amoxycillin . Metronidazole resistance was commoner in younger patients (P = 0.0004) and macrolide resistance was commoner in those born outside Australia or New Zealand (P = 0.03) . CONCLUSIONS: We found substantial resistance to metronidazole, and emerging clarithromycin resistance, but complete susceptibility to amoxycillin, tetracycline, gentamicin and cefaclor . These factors may influence the effectiveness of presently recommended eradication regimens.

Cas Lek Cesk, 2000 Oct 11, 139(20), 615 - 9
{60 years' of antibiotics--resistance: a time bomb for the third millenium}; Blahova J et al.; More then 50 years of antibiotic era has brought to clinical use many antibiotics with, specific and also with broad spectrum activity . Excessive use of antibiotics brought and brings serious problems--the resistance of many important bacteria and so the loss of effectivity of these scarce substances . Significant negative role in this process has the transferability of the resistance genes between bacteria . Bacterial strains are able to accept block of genes for multiresistance, exchange them inter species and spread to susceptible ones . There is an important task for the 3rd millennium to reduce the prevalence of the antibiotic resistance . Changes of the empiric treatment regiments (reduction in antibiotic use, antibiotic rotation, infection control, monitoring of resistance) and the strict hospital hygiene could help to solve the problems of antibiotic resistance in the future.

Can J Gastroenterol, 2000 Nov, 14(10), 895 - 9
Helicobacter pylori antibiotic resistance: trends over time; Lahaie RG et al.; Resistance to antibiotics can be a major problem in the treatment of bacterial infections . As the use of antibiotics increases, bacterial resistance to these agents is rising and in many cases is responsible for the failure of treatment regimens . Although the treatment of Helicobacter pylori infection requires the use of more than one antibiotic to obtain adequate eradication rates, the efficacy of the currently used antibiotic combinations has been shown to be decreased by resistance to one of the antibiotics . The use of antibiotics in regiments for the treatment of H pylori is increasing in many countries, including Canada . This increase is both in the use of these antibiotics alone for the treatment of nongastrointestinal infections and in their use in association with proton pump inhibitors for the treatment of H pylori infection . In several European and Asian countries, where resistance to antibiotics is being monitored, it has been demonstrated the H pylori resistance to metronidazole and to clarithromycin increased throughout the 1990s . Thus far, the data available in Canada do not show increased resistance to either of these antibiotics . As for other antibiotics used in the treatment of H pylori infection such as tetracycline and amoxicillin, the rate of resistance to these agents is still very low and does not constitute a significant problem . Because the efficacy of the regimens used in the treatment of H pylori infection is compromised by resistance to the antibiotics used, it is important that H pylori resistance rate in Canada and throughout the world continue to be monitored . Only with such reliable data can the most optimal regimens be recommended.

Clin Resour Manag, 2000 Mar, 1(3), 42 - 4, 33
Ionic silver dressing could be next wave in infection control if product demonstrates value; Spontaneous mutations that confer antibiotic resistance in Helicobacter pylori; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, CanadaIn this study, we systematically examined in vitro frequencies and spectra of the spontaneous mutations in Helicobacter pylori that confer resistance to clarithromycin (Cla(r)), metronidazole (Mtz(r)), amoxicillin (Amx(r)), ciprofloxacin (Cip(r)), and rifampin (Rif(r)) . The mutation rate of Rif(r) or Cip(r) determined in a fluctuation assay is 1 x 10(-8) to 2 x 10(-8) per cell per division . In contrast, the mutation rates of Cla(r), Mtz(r), and Amx(r) are much lower (<10(-9)) . However, Mtz(r) mutants could be readily selected in vitro by using the serial passage method, suggesting that the mutagenic effect and selective effect of a sublethal dose of metronidazole contribute to the rapid development of Mtz(r) . Analysis of spontaneous Rif(r), Cla(r), and Cip(r) mutants confirmed previous results indicating that mutations within the rpoB gene, the 23S rRNA gene, and the gyrA gene, respectively, are responsible; also, several new mutant alleles were identified . Mtz(r) mutants resulted most frequently, but not always, from mutations in the rdxA gene . DNA fragments containing each mutant allele could readily transform susceptible H . pylori strains to resistance, confirming that each mutant allele is responsible for the resistance phenotype.

Bioelectromagnetics, 2001 Feb, 22(2), 129 - 37
Increased antibiotic resistance of E . coli exposed to static magnetic fields; Stansell MJ et al.; The present study demonstrates that exposure of bacteria to medium strength static magnetic fields can significantly alter antibiotic sensitivity . Cultures of Escherichia coli were exposed to fields produced by permanent magnets . Samples of bacterial cultures continuously growing in the presence and in the absence of static magnetic fields were left untreated or were treated with an antibiotic and measured at 45 min intervals for cell growth and survival . It was found that exposure of E . coli to the static fields significantly increased antibiotic resistance . Bioelectromagnetics 22:129-137, 2001 . Published 2001 Wiley-Liss, Inc.

Croat Med J, 2001 Feb, 42(1), 45 - 8
Antibiotic-resistance patterns of Helicobacter pylori in Croatia: cohort study; Rosandic M; AIM . To provide information on regional sensitivity of H . pylori to antibiotic treatment by investigating the rate of H . pylori eradication in Croatia . METHODS . The study included 217 outpatients (107 women and 110 men), with gastrointestinal symptoms and H . pylori positive finding . They received the first-line and second-line treatments . The first-line treatment included triple therapies with either omeprazole (omeprazole, amoxicillin, and metronidazole - OAM), or pantoprazole (pantoprazole, amoxicillin, and metronidazole - PAM), or a combination of ranitidine bismuth citrate, amoxicillin, and azithromycin (RBAAz) . If this therapy failed, clarithromycin was used in the second-line treatment . RESULTS . H . pylori was eradicated in 93% of the patients, whereas in 7% it was resistant to all administered therapies . The efficacy of OAM or PAM first-line treatments in H . pylori eradication, including resistant patients, was 70%, and of RBAAz treatment 95% . The RBAAz treatment had the highest eradication rate . In the second-line treatment, clarithromycin eradicated 45% of the remaining H . pylori strains that had not reacted to metronidazole and azithromycin administered either alone or in combination with ranitidine bismuth citrate . CONCLUSION . Optimal therapy for the eradication of H . pylori infection is the RBAAz treatment, whereas metronidazole cannot be recommended because of the high rate of resistance of H . pylori to that antibiotic.

Microbes Infect, 2000 Dec, 2(15), 1913 - 4
'Infectious web'; Kotra LP et al.; A comprehensive list of all known bacterial pathogens of humans is now available at various web-sites on the internet . The sites contain hyperlinks to original scientific literature, along with general information on laboratory testing, antibiotic resistance and clinical treatment . More specific sites highlight the fungus Pneumocystic carinii, arguably the main cause of pneumonia in immunosuppressed individuals.

J Bacteriol, 2001 Feb, 183(4), 1320 - 8
Characterization of the dnaK multigene family in the Cyanobacterium Synechococcus sp . strain PCC7942; Nimura K et al.; The cyanobacterium Synechococcus sp . strain PCC7942 has three dnaK homologues (dnaK1, dnaK2, and dnaK3), and a gene disruption experiment was carried out for each dnaK gene by inserting an antibiotic resistance marker . Our findings revealed that DnaK1 was not essential for normal growth, whereas DnaK2 and DnaK3 were essential . We also examined the effect of heat shock on the levels of these three DnaK and GroEL proteins and found a varied response to heat shock, with levels depending on each protein . The DnaK2 and GroEL proteins exhibited a typical heat shock response, that is, their synthesis increased upon temperature upshift . In contrast, the synthesis of DnaK1 and DnaK3 did not respond to heat shock; in fact, the level of DnaK1 protein decreased . We also analyzed the effect of overproduction of each DnaK protein in Escherichia coli cells using an inducible expression system . Overproduction of DnaK1 or DnaK2 resulted in defects in cell septation and formation of cell filaments . On the other hand, overproduction of DnaK3 did not result in filamentous cells; rather a swollen and twisted cell morphology was observed . When expressed in an E . coli dnaK756 mutant, dnaK2 could suppress the growth deficiency at the nonpermissive temperature, while dnaK1 and dnaK3 could not suppress this phenotype . On the contrary, overproduction of DnaK1 or DnaK3 resulted in growth inhibition at the permissive temperature . These results suggest that different types of Hsp70 in the same cellular compartment have specific functions in the cell.

Med Clin North Am, 2000 Nov, 84(6), 1407 - 29
Antibiotic resistance; Cunha BA; Widespread resistance problems exist today in a global sense because of the incorporation of antibiotics with a high resistance potential into animal feeds and because of the uncontrolled use of antibiotics with a high resistance potential in the clinical setting . The only proven method of controlling nonoutbreak resistance problems in hospitals is to limit the hospital formulary to antibiotics with little or no resistance potential . The control of multiresistant organisms in outbreaks occurring in hospitals is best contained using appropriate infection control containment measures . Physicians treating infections in the community, with all other factors being equal, should preferentially select antibiotics with a low resistance potential . The titles and headings of much of the resistance literature are misleading . Articles should not contain fluoroquinolone resistant in the title when ciprofloxacin-resistant organisms are described . Many articles concerning penicillin-resistant pneumococci are entitled fluoroquinolone-resistant S . pneumoniae . These articles describe ciprofloxacin-resistant S . pneumoniae and not resistance to other fluoroquinolones . The same error is perpetuated in describing third-generation cephalosporins and carbapenems . Virtually all of the resistance problems associated with third-generation cephalosporins and carbapenems are due to ceftazidime or imipenem . More precise titling in the literature would remind physicians that antibiotic resistance is related to a specific agent and not class phenomena.

Am J Gastroenterol, 2000 Dec, 95(12), 3393 - 8
Esomeprazole-based Helicobacter pylori eradication therapy and the effect of antibiotic resistance: results of three US multicenter, double-blind trials; Laine L et al.; OBJECTIVES: To determine the efficacy of once-daily esomeprazole plus antibiotics for eradication of Helicobacter pylori, to assess the effect of antibiotic resistance on eradication rate, and to define the rate of emergent resistance . METHODS: Three separate randomized trials were performed in H . pylori-positive patients with a duodenal ulcer or history of documented duodenal ulcer within 5 yrs: 1) esomeprazole (40 mg once daily), amoxicillin (1 g b.i.d.), and clarithromycin (500 mg b.i.d.; this combination will be referred to as EAC) versus esomeprazole (40 mg once daily) plus clarithromycin (500 mg twice daily; this combination will be referred to as EC); 2) EAC versus esomeprazole (40 mg once daily; E); and 3) EC versus E . Therapy was given for 10 days . Endoscopy and biopsies for CLOtest, histology, and culture with susceptibility testing were done at baseline and 4 wk after completion of therapy . RESULTS: Per-protocol and intent-to-treat eradication rates, respectively, were as follows . For EAC versus EC in study 1 (N = 448), 84 versus 55% and 77 versus 52% (p < 0.001); for EAC versus E in study 2 (N = 98), 85 versus 5% and 78 versus 4% (p < 0.001); for EC versus E in study 3 (N = 66), 50% versus 0 and 46% versus 0 (p < 0.05) . The 15% of patients in the combined studies with baseline clarithromycin resistance had significantly lower rates of eradication than those with susceptible strains (EAC: 45 vs . 89%; EC: 13 vs . 61%) . Emergent resistance was less common after treatment with EAC {2/6 (33%)} than with EC (23/27 {85%}) . CONCLUSIONS: Ten-day triple therapy with once-daily esomeprazole plus twice-daily amoxicillin and clarithromycin achieves an eradication rate virtually identical to that of the twice-daily proton pump inhibitor-based triple therapies . Baseline clarithromycin resistance, present in 15% of patients, predicts a markedly decreased rate . Use of an amoxicillin-containing regimen may decrease emergence of clarithromycin resistance.

Genetica, 2000, 108(1), 47 - 51
Visualization of pathogenicity regions in bacteria; Friis C et al.; We show here how pathogenicity islands can be analysed using GenomeAtlases, which is a method for visualising repeats, DNA structural characteristics, and base composition of chromosomes and plasmids . We have applied this method to the E . coli plasmid pO157, and the Y . pestis plasmid pPCP1 . In both cases pathogenic genes were shown to differ in A + T content and structural properties . Furthermore, examination of an antibiotic resistance gene cluster from S . typhimurium showed that the same was true for genes encoding antibiotic resistance.

Dig Liver Dis, 2000 Nov, 32(8), 667 - 72
Incidence of secondary Helicobacter pylori resistance to antibiotics in treatment failures after 1-week proton pump inhibitor-based triple therapies: a prospective study; Pilotto A et al.; BACKGROUND: Antibiotic-resistant Helicobacter pylori strains are becoming increasingly prevalent, although it is not clear to what extent the new resistant organisms will spread . AIM: To evaluate the incidence of secondary Helicobacter pylori resistance to metronidazole, clarithromycin and/or amoxycillin after one-week proton pump inhibitor based triple therapy failure in patients who were, before therapy infected with Helicobacter pylori strains susceptible to these antibiotics . PATIENTS AND METHODS: Enrolled in the study were 97 consecutive Helicobacter pylori-positive subjects infected by Helicobacter pylori strains susceptible to metronidazole, clarithromycin and amoxycillin . Activity of tested antibiotics was determined by means of the E-test . Patients were treated for seven days with a proton pump inhibitor, omeprazole 20 mg twice daily or pantoprazole 40 mg once daily, plus clarithromycin 250 mg twice daily and metronidazole 250 mg four times daily; or with a proton pump inhibitor plus amoxycillin 1 g twice daily and clarithromycin 500 mg twice daily . Two months after completion of therapy, endoscopy and gastric biopsies for histology, rapid urease test and culture were repeated . RESULTS: Four patients were dropped from the study Overall Helicobacter pylori cure rates expressed as both intention-to-treat and per-protocol analyses, were, respectively 80% (40/50) and 81.6% (40/49) with proton pump inhibitor, clarithromycin and metronidazole and 76.6% (36/47) and 81.8% (36/44) with proton pump inhibitor amoxycillin and clarithromycin . No significant differences were observed between the two treatments . Subjects in whom treatment failed were significantly younger and had less active ulcer than cured patients . Of treatment failures, 70.6% (12 out of 17 subjects) de veloped a secondary resistance to metronidazole (35.33% and/or clarithromycin (64.7%) . Secondary antibiotic resistance occurred in 77 . 8% of treatment failures treated with proton pump inhibitor, clarithromycin and metronidazole and in 62.5% of those treated with proton pump inhibitor, amoxycillin and clarithromycin . Considering all patients treated, the overall incidence of secondary metronidazole and/or clarithromycin resistance after therapy was reported in 12.9% of subjects (12 out of 93 treated patients) . CONCLUSIONS: Secondary Helicobacter pylori resistances to metronidazole and/or clarithromycin occurred in large percentages in patients with treatment failure after the one-week proton pump inhibitor-based triple therapies, proton pump inhibitor, clarithromycin and metronidazole and proton pump inhibitor, amoxycillin and clarithromycin . It is likely that new antibiotics or treatment strategies will be needed in the near future to successfully treat Helicobacter pylori infection.

Pediatrics . 2001 Jan;107(1):E6.
The effect of a community intervention trial on parental knowledge and awareness of antibiotic resistance and appropriate antibiotic use in children; Trepka MJ et al.; BACKGROUND: Overuse of antibiotics for children's upper respiratory infections is widespread and contributes to the emergence of antibiotic-resistant bacteria . OBJECTIVE: To assess changes in knowledge and awareness regarding antibiotic resistance and appropriate antibiotic use after community-wide educational interventions to reduce inappropriate antibiotic use . DESIGN: Baseline survey conducted during June through July 1997 and postintervention survey of baseline participants during June through August 1998 . SETTING: Communities in northern Wisconsin . PARTICIPANTS: Parents of 729 randomly selected children <4 years of age were called until 215 in each of the intervention and control areas were reached . Of the 430 baseline participants, 365 (85%) participated in the postintervention survey . INTERVENTION: Parent-oriented activities included distribution of materials and presentations . Physician-oriented activities included formal presentations and small group meetings . OUTCOME MEASURE: Change in awareness about antibiotic resistance and knowledge about antibiotic indications . RESULTS: A higher proportion of parents in the intervention area (53%) were exposed to 2 or more local educational messages, compared with the control area (23%) . From the baseline to the postintervention survey, the percentage of parents with a high degree of antibiotic resistance awareness increased more in the intervention area (58% to 73%) than in the control area (60% to 65%) . In the intervention area, there was also a larger increase in knowledge regarding appropriate indications for antibiotic use, compared with the control area . The proportion of parents who expected an antibiotic for their child and did not receive one declined in the intervention area (14% to 9%), while it increased in the control area (7% to 10%) . In addition, the percentage of parents in the intervention area who brought their child to another physician because they did not receive an antibiotic decreased (5% to 2%), while it increased in the control area (2% to 4%) . CONCLUSION: Parental knowledge and awareness about antibiotic indications and antibiotic resistance can be changed with educational interventions directed at parents and clinicians.

Infect Immun, 2001 Jan, 69(1), 325 - 35
vimA gene downstream of recA is involved in virulence modulation in Porphyromonas gingivalis W83; Abaibou H et al.; A 0.9-kb open reading frame encoding a unique 32-kDa protein was identified downstream of the recA gene of Porphyromonas gingivalis . Reverse transcription-PCR and Northern blot analysis showed that both the recA gene and this open reading frame are part of the same transcriptional unit . This cloned fragment was insertionally inactivated using the ermF-ermAM antibiotic resistance cassette to create a defective mutant by allelic exchange . When plated on Brucella blood agar, the mutant strain, designated P . gingivalis FLL92, was non-black pigmented and showed significant reduction in beta-hemolysis compared with the parent strain, P . gingivalis W83 . Arginine- and lysine-specific cysteine protease activities, which were mostly soluble, were approximately 90% lower than that of the parent strain . Expression of the rgpA, rgpB, and kgp protease genes was the same in P . gingivalis FLL92 as in the wild-type strain . In contrast to the parent strain, P . gingivalis FLL92 showed increased autoaggregration in addition to a significant reduction in hemagglutinating and hemolysin activities . In in vivo experiments using a mouse model, P . gingivalis FLL92 was dramatically less virulent than the parent strain . A molecular survey of this mutant and the parent strain using all known P . gingivalis insertion sequence elements as probes suggested that no intragenomic changes due to the movement of these elements have occurred in P . gingivalis FLL92 . Taken together, these results suggest that the recA downstream gene, designated vimA (virulence-modulating gene), plays an important role in virulence modulation in P . gingivalis W83, possibly representing a novel posttranscriptional or translational regulation of virulence factors in P . gingivalis.

Trends Microbiol, 2000 Dec, 8(12), 554 - 9
What is antibiotic resistance and how can we measure it?
Davison HC, Low JC, Woolhouse ME.
Antibiotic resistance is being found with increasing frequency in both pathogenic and commensal bacteria of humans and animals . Quantifying resistance within and between bacterial and host populations presents scientists with complex challenges in terms of laboratory methodologies and sampling design . Here, we discuss, from an epidemiological perspective, how antibiotic resistance can be defined and measured and the limitations of current approaches.

Can J Gastroenterol, 2000 Nov, 14(10), 885 - 9
Effects of in vitro antibiotic resistance on treatment: bismuth-containing regimens; Chiba N; Bismuth compounds remain useful for Helicobacter pylori eradication therapy . These include colloidal bismuth subcitrate (CBS), bismuth subsalicylate (BSS) and, most recently, ranitidine bismuth citrate (RBC) . CBS appears to prevent the development of imidazole resistance when coadministered with nitroimidazoles . Traditional triple therapy with bismuth, metronidazole and tetracycline or amoxicillin (BMT/A) only partially overcomes metronidazole resistance . However, the addition of a PPI to bismuth triple therapy largely overcomes established metronidazole resistance if treatment is given for at least one week or more . When RBC rather than PPI is used with clarithromycin, this dual regimen appears to be more effective in preventing the development of secondary clarithromycin resistance . The triple combination of RBC, metronidazole and clarithromycin appears to be effective against metronidazole resistant strains of H pylori . Thus, overall, there is some evidence that bismuth compounds may prevent the development of antibiotic resistance and that existing antibiotic resistance may at least be partially overcome in vitro and in vivo . With the growing emergence of H pylori resistance to metronidazole and clarithromycin, further research to clarify the role of bismuth compounds is required.

Can J Gastroenterol, 2000 Nov, 14(10), 879 - 82
Epidemiology of the antibiotic resistance of Helicobacter pylori in Canada; Fallone CA; BACKGROUND: The rate of Helicobacter pylori resistance to antibiotics determines the cure rate of treatment regimens containing such antibiotics . AIMS: To review the literature to determine the rates of H pylori resistance to metronidazole and clarithromycin in Canada, and whether these rates vary in different regions of Canada . METHODS: The literature was reviewed extensively for the prevalence of antibiotic-resistant H pylori in Canada by searching MEDLINE from January 1980 to May 1999, as well as abstracts of the American Gastroenterology Association Digestive Disease Week, Canadian Digestive Disease Week and The European H pylori Study Group Meetings from January 1995 to May 1999 . RESULTS: Eleven studies that estimated H pylori resistance to metronidazole resistance and nine that estimated resistance to clarithromycin in Canada were identified . Rates of resistance for metronidazole and clarithromycin varied from 11% to 48% and 0% to 12%, respectively . Studies that obtained their estimates using the E-test and those that did not clearly exclude patients who had undergone previous attempts at H pylori eradication had higher estimates of resistance, accounting for this variability in results . CONCLUSIONS: The prevalence of primary H pylori resistance in Canada appears to be 18% to 22% for metronidazole and less than 4% for clarithromycin . These rates appear to be consistent across the different regions studied in Canada, but many regions have not been studied.

Can J Gastroenterol, 2000 Nov, 14(10), 862 - 8
Implications of antibiotic resistance in the management of Helicobacter pylori infection: Canadian Helicobacter Study Group; Hunt RH et al.; Eradication of Helicobacter pylori from the gastric and duodenal mucosa is an important clinical goal in the treatment of infected patients with peptic ulcer disease and other H pylori-associated conditions . Although several oral drug combination regimens are associated with eradication rates of approximately 85% in controlled trials, the success rate in patients infected with a resistant strain of H pylori is closer to 75% . Resistance to metronidazole and clarithromycin, which are common components of combination treatment regimens, is of greatest concern . Reported rates of H pylori resistance to various antibiotics vary considerably . In Canada, the data documenting H pylori susceptibility are limited but suggest that resistance to these antibiotics varies geographically and within specific treatment groups . Although susceptibility testing is not a prerequisite for initial treatment of individual patients infected with H pylori, formal efforts to identify and monitor both the causes and prevalence of antibiotic resistance across Canada are a much needed step in the ongoing management of this important infection . Recommended treatment regimens may be useful, even for treating apparently resistant H pylori strains . However, it is important to understand the mechanisms of the development of resistant strains to manage patients with treatment failure better.

Can J Microbiol, 2000 Nov, 46(11), 992 - 7
Transplantation and subsequent behavior of mitochondria in cells of Phytophthora; Gu YH et al.; Mitochondria isolated from streptomycin-resistant (S(r)) protoplasts of Phytophthora parasitica were transferred into chloramphenicol-resistant (Cpr) protoplasts of P . parasitica or Phytophthora capsici with an average successful rate of 1.7 x 10(-4), using a selective medium containing streptomycin . No colonies appeared when self-fusion products of donor mitochondria or recipient protoplasts were exposed to the selective medium . Mitochondria isolated from Cpr protoplasts of P . capsici were also transferred into S(r) protoplasts of P . parasitica with a similar success rate using a selective medium containing chloramphenicol . Zoospores produced by the Cpr + S(r) intraspecific mitochondrial hybrid gave rise to S(r) and Cpr + S(r) cultures . The second generation zoospores produced by S(r) and Cpr + S(r) cultures also gave rise to S(r) and Cpr + S(r) cultures, suggesting the possible occurrence of fusion between some of the Cpr mitochondria and S(r) mitochondria, and the displacement of non-fused Cpr mitochondria in the receptor protoplast by the donor S(r) mitochondria . Zoospores produced by the interspecific mitochondrial hybrid gave rise to Cpr, S(r), Cpr + S(r), and Cps + Ss cultures . The second generation zoospores produced by Cpr + S(r) or S(r) cultures also gave rise to the same four types of cultures, suggesting the existence of residual antibiotic-sensitive mitochondria (Cps + Ss) in the parental isolates and the random distribution of Cpr, S(r), and Cps + Ss mitochondria during asexual reproduction . Results suggest that the phenotype of antibiotic resistance/sensitivity was the end result of the interactions among the three types of mitochondria.

Int Microbiol, 1998 Dec, 1(4), 265 - 70
Bacterial evolution and the cost of antibiotic resistance; Lenski RE; Bacteria clearly benefit from the possession of an antibiotic resistance gene when the corresponding antibiotic is present . But do resistant bacteria suffer a cost of resistance (i.e., a reduction in fitness) when the antibiotic is absent? If so, then one strategy to control the spread of resistance would be to suspend the use of a particular antibiotic until resistant genotypes declined to low frequency . Numerous studies have indeed shown that resistant genotypes are less fit than their sensitive counterparts in the absence of antibiotic, indicating a cost of resistance . But there is an important caveat: these studies have put resistance genes into naive bacteria, which have no evolutionary history of association with the resistance genes . An important question, therefore, is whether bacteria can overcome the cost of resistance by evolving adaptations that counteract the harmful side-effects of resistance genes . In fact, several experiments (in vitro and in vivo) show that the cost of antibiotic resistance can be substantially diminished, even eliminated, by evolutionary changes in bacteria over rather short periods of time . As a consequence, it becomes increasingly difficult to eliminate resistant genotypes simply by suspending the use of antibiotics.

J Antimicrob Chemother, 2000 Dec, 46(6), 1029 - 31
Features and trends in Helicobacter pylori antibiotic resistance in Lisbon area, Portugal (1990-1999); Cabrita J et al.; The features of Helicobacter pylori antibiotic resistance in Lisbon from 1990 to 1999 were studied . Overall resistance rates to amoxycillin, tetracycline, metronidazole, clarithromycin and ciprofloxacin were 0, 0, 30.6, 19.0 and 9.6%, respectively . The incidence of resistance to clarithromycin was much higher in isolates from children (44.8%) than adults (14.6%) . For metronidazole, the contrary was observed (children: 19.0%, adults: 32.3%) . Ciprofloxacin-resistant isolates were all from adult patients . Concerning the adult population, the resistance rate to metronidazole showed a slight increase during the decade, while for clarithromycin and ciprofloxacin a significant increase was observed (4.6 to 22.0% and 0 to 20.9%, respectively).

Genetics, 2000 Dec, 156(4), 1471 - 81
Compensatory evolution in rifampin-resistant Escherichia coli; Reynolds MG; This study examines the intrinsic fitness burden associated with RNA polymerase (rpoB) mutations conferring rifampin resistance in Escherichia coli K12 (MG1655) and explores the nature of adaptation to the costs of resistance . Among 28 independent Rif(r) mutants, the per-generation fitness burden (in the absence of rifampin) ranged from 0 to 28%, with a median of 6.4% . We detected no relationship between the magnitude of the cost and the level of resistance . Adaptation to the costs of rif resistance was studied by following serial transfer cultures for several Rif(r) mutants both in the presence of rifampin and in the absence . For cultures evolved in the absence of rifampin, single clones isolated after 200 generations were more fit than their ancestor; we saw no association between increased fitness and changes in the level of rifampin resistance; and in all cases, increased fitness was due to compensatory mutations, rather than to reversion to drug sensitivity . However, in the parallel evolution experiments in the presence of rifampin, overall levels of resistance increased as did relative fitness-for all strains save one that had an initially high level of resistance . Among the evolved clones tested, five (of seven) demonstrated increased transcription efficiency (assessed using a semiquantitative RT-PCR protocol) . The implications of these results for our understanding of adaptive molecular evolution and the increasing clinical problem of antibiotic resistance are discussed.

FEMS Microbiol Lett, 2000 Dec 1, 193(1), 51 - 6
Purification and analysis of expression of the stationary phase-inducible slp lipoprotein in Escherichia coli: role of the Mar system; Price GP et al.; Entrance into the stationary phase in Escherichia coli induces a group of stress response genes including slp, which encodes an outer membrane lipoprotein . Glucose limitation is sufficient, but not necessary, for the increase in slp expression . The Slp protein was purified and an antibody-based assay was developed, which enabled identification of Slp as spot R2226 (G018.1) in the E . coli gene-protein database . Although Slp is a major membrane component in stationary phase cultures grown in complex medium, no significant changes in resistance to oxidative stress or membrane perturbants were found in a slp null mutant strain . The presence or absence of multiple antibiotic resistance (Mar) A did not alter the final stationary phase levels of Slp . However, the Mar system could modestly influence the level of slp expression during the transition from exponential to stationary growth phase . Accumulation of Slp leads to a small increase in sensitivity to chloramphenicol.

Curr Treat Options Cardiovasc Med, 2000 Oct, 2(5), 451 - 459
Cardiovascular Dysfunction in Sepsis and Septic Shock; Landgarten MJ et al.; The optimal therapy for the treatment of sepsis and septic shock remains controversial . Many protocols are followed, using different strategies for initial resuscitation, cardiovascular monitoring, hemodynamic intervention, and eradication of infection . Overall, an aggressive approach to the management of cardiovascular dysfunction in septic shock is warranted . Initially, large volume fluid resuscitation is instituted . Our first choice of resuscitation fluid is 0.9% normal saline . Invasive hemodynamic monitoring using a flotation pulmonary artery catheter as well as invasive arterial blood pressure monitoring is a necessity in the hemodynamic management of septic shock . If the patient remains hypotensive (mean arterial pressure < 65 mm Hg) after adequate volume resuscitation has been established (pulmonary capillary wedge pressure 12 to 15 mm Hg), then vasopressor agents must be instituted . Our first choice is usually dopamine . In patients who remain hypotensive after maximal doses of dopamine are reached, norepinephrine is added . If these agents generate excessive tachycardia or if tachyarrhythmias develop, phenylephrine can be substituted or added . Inotropic agents are useful if the patient demonstrates hypotension with a low cardiac output state . Dobutamine is the agent of choice . We initiate broad-spectrum empiric antibiotics at presentation, modifying the exact regimen based on 1) site of infection; 2) prevailing organisms and antibiotic resistance patterns in the patient's environment; and 3) other specific risk factors (immunosuppression, chronic disease, exposure and vaccination history, invasive medical devices) . When appropriate, aggressive surgical debridement is pursued . Currently, there are no clinical data to support the use of antagonists for sepsis mediators, although various clinical trials remain underway . Steroids are contraindicated except for adrenal replacement therapy.

Curr Infect Dis Rep, 1999 Aug, 1(3), 238 - 244
Catheter-Related Bloodstream Infection; Calfee DP et al.; Central venous catheters are associated with the vast majority of nosocomial, catheter-related bloodstream infections (CR-BSI) . Despite identification of multiple effective methods for preventing CR-BSI, it remains an important clinical problem . Catheters coated with anti-infective substances, such as chlorhexidine and silver sulfadiazine or rifampin and minocycline, have shown promising results in recent clinical trials, but confirmatory studies by different investigators are still needed . Concern has also been raised about widespread use of clinically important antibiotics on catheter surfaces, which may promote the development of antibiotic resistance . More accurate and cost-effective methods of diagnosing CR-BSI are desirable . Recent studies have evaluated endoluminal brush sampling and differential blood culture growth rates, which may provide acceptable accuracy without requiring removal of long-dwelling catheters, but the accuracy of these techniques needs to be confirmed in other studies.

Int J Biochem Cell Biol, 2000 Oct, 32(10), 1029 - 43
The effects of salicylate on bacteria; Price CT et al.; Salicylate and related compounds, such as aspirin, have a variety of effects in eucaryotic systems and are well known for their medicinal properties . Salicylate also has numerous effects on bacteria, yet only a handful of individuals within the scientific community appreciate these findings . From a bacterial viewpoint, growth in the presence of salicylate can be both beneficial and detrimental . On one hand, growth of certain bacteria in the presence of salicylate can induce an intrinsic multiple antibiotic resistance phenotype . On the other hand, growth in the presence of salicylate can reduce the resistance to some antibiotics and affect virulence factor production in some bacteria . This review provides an overview of the effects salicylate has on various bacterial species.

Int J Antimicrob Agents, 2000 Nov, 16(3), 245 - 8
Factors affecting the variation in antibiotic resistance of Helicobacter pylori over a 3-year period; Ferrero M et al.; Strains of Helicobacter pylori, isolated from 300 patients between 1996 and 2000 were tested for their sensitivity to clarithromycin, metronidazole and amoxycillin . Primary resistances (95% CI) were 9 . 7% for clarithromycin and 21.7% for metronidazole . No strains were resistant to amoxycillin . There was no significant difference between the number of resistant strains in the male and female groups . Clarithromycin resistance was more common in older patients (P<0.01) and metronidazole resistance was more common in patients with peptic ulcer compared with patients with chronic gastritis (P<0 . 05) . Logistic regression analysis confirmed these results.

Infect Control Hosp Epidemiol, 2000 Oct, 21(10), 680 - 3
Antibiotic use in long-term-care facilities: many unanswered questions; Loeb M; The extensive use of antibiotics in long-term-care facilities has led to increasing concern about the potential for the development of antibiotic resistance . Relatively little is known, however, about the quantitative relation between antibiotic use and resistance in this population . A better understanding of the underlying factors that account for variance in antibiotic use, unexplained by detected infections, is needed . To optimize antibiotic use, evidence-based standards for empirical antibiotic prescribing need to be developed . Limitations in current diagnostic testing for infection in residents of long-term-care facilities pose a substantial challenge to developing such standards.

J Mol Microbiol Biotechnol, 2000 Oct, 2(4), 501 - 4
ABCdb: an ABC transporter database; Quentin Y et al.; We present the first release of a database devoted to the ATP-binding cassette (ABC) protein domains (ABCdb) . The ABC proteins are involved in a wide variety of physiological processes in Archea, Bacteria and Eucaryota where they are encoded by large families of paralogous genes . The majority of ABC domains energize the transport of compounds across the membranes . In bacteria, ABC transporters are involved in the uptake of a wide range of molecules and in mechanisms of virulence and antibiotic resistance . In eukaryotes, most of them are involved in drug resistance and in human cells, many are associated with diseases . Sequence analysis reveals that members of the ABC superfamily can be organized into sub-families and suggests that they have diverged from common ancestral forms . In this release, ABCdb includes the inventory and assembly of the ABC transporter systems of completely sequenced genomes . In addition to the protein entries, the database comprises information on functional domains, sequence motifs, predicted trans-membrane segments, and signal peptides . It also includes a classification in sub-families of the ABC systems as well as a classification of the different partners of the systems . Evolutionary trees and specific sequence patterns are provided for each sub-family . The database is endowed with a powerful query system and it was interfaced with blastP2 program for similarity searches . ABCdb has been developed in the ACeDB format, a database system developed by Jean Thierry-Mieg and Richard Durbin . ABCdb can be accessed via the World Wide Web .

Arch Med Res, 2000 Jul-Aug, 31(4), 329 - 52
Update in internal medicine; Lopez-Jimenez F et al.; More than 500,000 new medical articles are published every year and available time to keep updated is scarcer every day . Nowadays, the task of selecting useful, consistent, and relevant information for clinicians is a priority in many major medical journals . This review has the aim of gathering the results of the most important findings in clinical medicine in the last few years . It is focused on results from randomized clinical trials and well-designed observational research . Findings were included preferentially if they showed solid results, and we avoided as much as possible including only preliminary data, or results that included only non-clinical outcomes.Some of the most relevant findings reported here include the significant benefit of statins in patients with coronary artery disease even with mean cholesterol level . It also provides a substantial review of the most significant trials assessing the effectiveness of IIb/IIIa receptor blockers . In gastroenterology many advances have been made in the H . pylori eradication, and the finding that the cure of H . pylori infection may be followed by gastroesophageal reflux disease . Some new antivirals have shown encouraging results in patients with chronic hepatitis . In the infectious disease arena, the late breaking trials in anti-retroviral disease are discussed, as well as the new trends regarding antibiotic resistance . This review approaches also the role of leukotriene modifiers in the treatment of asthma and discusses the benefit of using methylprednisolone in patients with adult respiratory distress syndrome, among many other advances in internal medicine.

Med J Aust, 2000 Oct 2, 173 Suppl, S51 - 3
Conjugate pneumococcal vaccines for aboriginal children in Australia; Torzillo PJ et al.; Research indicates a high burden of pneumococcal disease and great potential benefits of conjugate vaccines in Indigenous Australian children, who should have high priority for delivery of these vaccines . Incidence of invasive pneumococcal disease in Indigenous people in central Australia is the highest reported in the world (2053 per 100,000 persons per year in those aged under two years) . Acute respiratory infection is a major cause of morbidity in Indigenous children in rural and remote areas . Early pneumococcal colonisation of the nasopharynx and high rates of carriage are seen in Indigenous children, and are probably related to their high rates of ear disease . Current seven-valent conjugate vaccines are likely to cover about two-thirds of invasive isolates in Indigenous Australian children; 11-valent vaccines will cover a higher proportion . Questions remain about the best vaccine carrier protein and the likely impact of vaccine on ear disease, pneumococcal carriage and antibiotic resistance.

Proc Natl Acad Sci U S A, 2000 Nov 7, 97(23), 12643 - 8
Postsegregational killing does not increase plasmid stability but acts to mediate the exclusion of competing plasmids; Cooper TF et al.; Postsegregational killing (PSK) systems consist of a tightly linked toxin-antitoxin pair . Antitoxin must be continually produced to prevent the longer lived toxin from killing the cell . PSK systems on plasmids are widely believed to benefit the plasmid by ensuring its stable vertical inheritance . However, experimental tests of this "stability" hypothesis were not consistent with its predictions . We suggest an alternative hypothesis to explain the evolution of PSK: that PSK systems have been selected through benefiting host plasmids in environments where plasmids must compete during horizontal reproduction . In this "competition" hypothesis, success of PSK systems is a consequence of plasmid-plasmid competition, rather than from an adaptive plasmid-host relationship . In support of this hypothesis, a plasmid-encoded parDE PSK system mediated the exclusion of an isogenic DeltaparDE plasmid . An understanding of how PSK systems influence plasmid success may provide insight into the evolution of other determinants (e.g., antibiotic resistance and virulence) also rendering a cell potentially dependent on an otherwise dispensable plasmid.

Aliment Pharmacol Ther, 2000 Oct, 14 Suppl 3, 23 - 30
Review article: the continuing dilemma of dyspepsia; Stanghellini V et al.; Dyspepsia drains a substantial proportion of healthcare resources in industrialized countries and an appropriate management strategy is needed . An aetiological role for Helicobacter pylori infection has been demonstrated in a number of pathological conditions associated with dyspepsia, such as peptic ulcer and gastric malignancies, but not in functional dyspepsia . Endoscopy and diagnosis-based treatment, H . pylori testing and eradication therapy, history taking and empirical therapy, are the main tools that are currently available for managing patients with upper gastrointestinal symptoms . Endoscopy identifies malignancies and organic diseases of the proximal gut and therefore provides reassurance to both doctors and patients . It should be recommended in older patients with suspicious symptoms and it has proven to be more cost-effective than empirical H2-receptor antagonists in patients with ulcer-like symptoms . Empirical eradication in all dyspeptics without suspicious symptoms is a cost-effective approach that cures the majority of peptic ulcers . Nevertheless, it does not control symptoms in the majority of patients, it may exacerbate gastro-oesophageal reflux disease, and it encourages antibiotic resistance . The realities of current clinical practice require empirical therapy in most, if not all, the dyspeptics seen by general practitioners . A detailed history taking can help to diagnose gastro-oesophageal reflux disease and to identify suspicious symptoms . Furthermore, identification of dyspepsia subgroups may provide guidance for empirical therapy . Nevertheless, even analysis of individual symptoms does not provide a sufficient diagnostic yield to differentiate functional from organic dyspepsia and appropriate investigations are needed in patients with poor response to short-term therapy or frequent relapses.

Br J Nurs, 2000 Feb 24-Mar 8, 9(4), 225 - 30
Antibiotic resistance: a growing and multifaceted problem; Clark L; Antibiotic resistance is an increasing problem worldwide that is exacerbated by the overuse and misuse of antibiotics . Patients, pharmaceutical marketing, and the use of antibiotics in veterinary medicine and animal husbandry are important factors to consider in the emergence of resistance . Infection control measures to prevent the spread of antibiotic-resistant bacteria are compromised by poor compliance to basic measures such as handwashing and standards of environmental cleanliness . Wider epidemiological factors such as global travel and complacency towards public health must also be considered . This article aims to improve understanding of antibiotic resistance and suggests ways in which nurses can contribute towards the strategy to address the problem.

Ann Emerg Med, 2000 Oct, 36(4), 320 - 7
Antibiotic prescribing for patients with colds, upper respiratory tract infections, and bronchitis: A national study of hospital-based emergency departments; Stone S et al.; STUDY OBJECTIVE: Antibiotics are often used to treat viral upper respiratory tract infections, even though they are usually ineffective . However, frequent inappropriate antibiotic use contributes to the emergence of drug-resistant bacterial pathogens . This study used a national database to evaluate antibiotic use in treating upper respiratory tract infections in emergency departments . METHODS: Data were obtained from the 1996 National Hospital Ambulatory Medical Care Survey . Antibiotic prescribing rates were examined for colds, upper respiratory tract infections, and acute bronchitis . Patients with comorbid conditions or secondary diagnoses, such as chronic obstructive pulmonary disease, pneumonia, sinusitis, and HIV, were excluded . Bivariate and multivariate analyses were used to assess predictors of antibiotic use . RESULTS: Overall, there were an estimated 2.7 million ED visits for colds, upper respiratory tract infections, and bronchitis by children and adults in 1996 . Antibiotics were prescribed for 24.2% (95% CI 18.9, 29.5) of patients with common colds and upper respiratory tract infections and for 42.2% (95% CI 35.2, 49.2) of patients with bronchitis . There were no significant associations between antibiotic use and patient race, sex, Hispanic ethnicity, geographic location, or source of payment . Antibiotics were prescribed less often by interns or residents than by staff or other physicians (odds ratio 0.43; 95% CI 0.19, 0.98), and patients younger than 18 years were less likely to receive antibiotics than adults (odds ratio 0.32; 95% CI 0.20, 0.52) . Smokers were 4.3 (95% CI 2.2, 8.3) times more likely to receive antibiotics than nonsmokers . CONCLUSION: Antibiotics are commonly prescribed for ED patients with upper respiratory tract infections even though they are usually ineffective in otherwise healthy adults . Efforts should be made to reduce inappropriate antibiotic use for the sake of containing costs, preventing side effects, and limiting the spread of antibiotic resistance.

Rev Prat, 2000 Sep 1, 50(13), 1442 - 5
{Treatment of Helicobacter pylori infection}; Lamouliatte H et al.; The recommended treatment of Helicobacter pylori infection is a seven-day course of the following regimen: a double dose proton-pump inhibitor (omeprazole 2 x 20 mg, or lansoprazole 2 x 30 mg, or pantoprazole 2 x 40 mg), associated with 2 antibiotics (amoxicillin 2 x 1,000 mg, clarithromycin 2 x 500 mg) . Eradication rate is around 65% . Main causes of failure are antibiotic resistance, bad compliance, early termination of therapy due to adverse events . A second line treatment is possible with substitution of clarithromycine by metronidazole (3 x 500 mg), a longer duration of treatment (14 days) and sometimes a quadritherapy with bismuth (not available in France).

J Clin Microbiol, 2000 Oct, 38(10), 3656 - 62
Genotypic determination of Mycobacterium tuberculosis antibiotic resistance using a novel mutation detection method, the branch migration inhibition M . tuberculosis antibiotic resistance test; Liu YP et al.; A novel method for the detection of any alteration within a defined sequence has recently been demonstrated (A . Lishanski, N . Kurn, and E . F . Ullman, Nucleic Acids Res . 28:E42, 2000; A . Lishanski, Clin . Chem . 46:9, 2000) . Essential to this method are the generation of partial duplexes that are capable of forming four-stranded structures and the ability to detect inhibition of branch migration in these structures (I . G . Panyutin and P . Hsieh, J . Mol . Biol . 230:413-424, 1993) . Inhibition of branch migration indicates the presence of sequence alteration . This mutation detection method, termed branch migration inhibition (BMI), is suitable for the detection of drug resistance in M . tuberculosis, which is frequently associated with multiple mutations within known genes . We describe the genotypic determination of the rifampin (RMP) and pyrazinamide (PZA) susceptibilities of M . tuberculosis isolates, using BMI coupled with the luminescence oxygen channeling immunoassay (LOCI) (E . F . Ullman et al., Proc . Natl . Acad . Sci . USA 91:5426-5430, 1994) . RMP and PZA resistances are associated with multiple mutations within the rpoB and pncA genes, respectively . M . tuberculosis genomic DNA samples prepared from 46 clinical isolates were used for genotypic determination of RMP resistance in a "blind study." Similarly, PZA resistance was determined using genomic DNA samples prepared from 37 clinical isolates . Full agreement of the genotypic and phenotypic determinations of drug susceptibility was demonstrated . RMP susceptibility determination directly from cells of 10 clinical isolates grown in culture was also demonstrated . The genotypic result of only 1 out of 10 isolates did not agree with the phenotypic susceptibility testing result . Sequence analysis of the rpoB gene of this clinical isolate revealed a single base substitution, most likely a silent point mutation . The new BMI-LOCI mutation detection method is a rapid and accurate procedure for the genotypic determination of the RMP and PZA susceptibilities of M . tuberculosis clinical isolates . BMI can also be detected by using commercially available automated enzyme-linked immunosorbent assay plate formats (Lishanski et al., Nucleic Acids Res . 28:E42, 2000).

Occup Med (Lond), 2000 Aug, 50(6), 375 - 6
Biological hazards: an overview; Payton C; Recent developments include new guidance from the UK Department of Health on the management of hepatitis B infected healthcare workers and evidence of the value of antiretroviral treatment in reducing transmission of HIV . The possibility of greater occupational transmissibility of hepatitis C and increasing antibiotic resistance remain of concern.

AORN J, 2000 Jul, 72(1), 64 - 6, 68-75 quiz 76-80
Antibiotic resistance--an alarming health care issue; Twomey C; Emerging highly infectious viral agents, resurgent diseases, and mutating bacteria have created a significant and costly health care crisis . Antibiotics that were proven to be definitive weapons against infectious disease now are losing their effectiveness . This article describes the etiology and impact of this global problem and offers perioperative nurses and other health care professionals guidelines about basic infection control and infectious disease prevention to help combat this crisis.

Cleve Clin J Med, 2000 Sep, 67(9), 625 - 8, 631-3
Treating acute exacerbations of chronic bronchitis in the face of antibiotic resistance; Adams SG et al.; Antibiotics can be effective against acute exacerbations of chronic bronchitis and chronic obstructive pulmonary disease, but with bacterial resistance to multiple antibiotics increasing worldwide, appropriate antibiotic selection is critical . Categorizing patients with acute exacerbations according to age, number of exacerbations per year, disease severity, degree of pulmonary impairment, and presence of comorbid conditions helps to direct therapy.

J Bacteriol, 2000 Oct, 182(19), 5440 - 7
The orf162b sequence of Rhodobacter capsulatus encodes a protein required for optimal levels of photosynthetic pigment-protein complexes; Aklujkar M et al.; The orf162b sequence, the second open reading frame 3' of the reaction center (RC) H protein gene puhA in the Rhodobacter capsulatus photosynthesis gene cluster, is shown to be transcribed from a promoter located 5' of puhA . A nonpolar mutation of orf162b was generated by replacing most of the coding region with an antibiotic resistance cartridge . Although the mutant strain initiated rapid photosynthetic growth, growth slowed progressively and cultures often entered a pseudostationary phase . The amounts of the RC and light harvesting complex I (LHI) in cells obtained from such photosynthetic cultures were abnormally low, but these deficiencies were less severe when the mutant was grown to a pseudostationary phase induced by low aeration in the absence of illumination . The orf162b mutation did not significantly affect the expression of a pufB::lacZ translationally in-frame gene fusion under the control of the puf promoter, indicating normal transcription and translation of RC and LHI genes . Spontaneous secondary mutations in the strain with the orf162b disruption resulted in a bypass of the photosynthetic growth retardation and reduced the level of light harvesting complex II . These results and the presence of sequences similar to orf162b in other species indicate that the Orf162b protein is required for normal levels of the photosynthetic apparatus in purple photosynthetic bacteria.

Curr Gastroenterol Rep, 1999 Aug, 1(4), 301 - 7
Microecologic approaches for traveler's diarrhea, antibiotic-associated diarrhea, and acute pediatric diarrhea; McFarland LV; Bacterial and viral diarrhea remain important causes of morbidity and mortality throughout the world . Current concerns with medical costs, increasing frequency of antibiotic resistance, and overuse of antibiotics in general have redirected therapeutic approaches for diarrhea from traditional drugs to the use of living therapeutic organisms . Awareness of the important role of normal flora in the microecology of the intestines in fighting infection, along with the recent availability of well-controlled clinical trials for these agents, has brought microecologic therapies to the forefront of clinical practice.

Acta Cient Venez, 2000, 51(1), 4 - 9
Construction of a cassette for cloning and analysis of replicons; Alonso G et al.; The aim of this work was the construction of a cassette, i.e., a non-replicative molecule formed by linkage of an antibiotic resistance gene and a multiple cloning site . This cassette would allow the cloning and analysis of a wide range of replicons . The aac(6')-lc amikacin gene was isolated and ligated to the multiple cloning site of the pUC18 vector . This construction was HindIII digested and cloned in the HindIII site of the vector . The resulting pHJ13 clone conferred to the recipient cells the ability to grow in presence of amikacin (cassette marker) and ampicillin (vector gene) . By restriction analysis, the cassette orientation was established . Cassette versatility is provided by the presence of the unaltered multiple cloning site segment, and also because it allows sequencing of any replication origin inserted . Cassette functionality was demonstrated by ligation to a replicative region of H plasmid pHH1457 . Presence of the ori region from pHH1457 and the aac(6')-lc gene was confirmed in E . coli transformed clones . The incompatibility properties of the pHH1457 and its capability to replicate in a Poll defective strain were preserved in the pHJII14 construct . Currently, the amikacin cassette is being used in the characterization of H Complex plasmids.

Appl Environ Microbiol, 2000 Sep, 66(9), 3722 - 6
Spatial patterns in antibiotic resistance among stream bacteria: effects of industrial pollution; McArthur JV et al.; The spatial distribution of antibiotic resistance to streptomycin and kanamycin was examined in natural bacterial communities of two streams . The proportion of resistant bacteria was substantially higher (P < 0.05) in the midreaches of an industrially perturbed stream, but no such pattern was apparent in an undisturbed reference stream . The highest relative frequency of resistance was found at the confluence of a tributary draining a nuclear reactor and industrial complex . Antibiotic resistance increased with distance upstream from the confluence and was positively correlated (r(2) = 0 . 54, P = 0.023) with mercury concentrations in the sediments . When the data for two years were compared, this pattern was stable for streptomycin resistance (paired t test, P < 0.05) but not for kanamycin resistance (P > 0.05) . Our results imply that heavy metal pollution may contribute to increased antibiotic resistance through indirect selection.

Antimicrob Agents Chemother, 2000 Sep, 44(9), 2485 - 91
Concentration-dependent selection of small phenotypic differences in TEM beta-lactamase-mediated antibiotic resistance; Negri MC et al.; In this paper, the first robust experimental evidence of in vitro and in vivo concentration-dependent selection of low-level antibiotic-resistant genetic variants is described . The work is based on the study of an asymmetric competition assay with pairs of isogenic Escherichia coli strains, differing only (apart from a neutral chromosomal marker) in a single amino acid replacement in a plasmid-mediated TEM-1 beta-lactamase enzyme, which results in the new TEM-12 beta-lactamase . The mixture was challenged by different antibiotic concentrations, both in vitro and in the animal model, and the selective process of the variant population was carefully monitored . A mathematical model was constructed to test the hypothesis that measured growth and killing rates of the individual TEM variants at different antibiotic concentrations could be used to predict quantitatively the strength of selection for TEM-12 observed in competition experiments at these different concentrations.

Mol Biotechnol, 1999 Dec 15, 13(3), 191 - 200
Mycobacteria: bugs and bugbears (two steps forward and one step back); Parish T et al.; The use of molecular techniques to study the mycobacteria has advanced greatly since the first genomic libraries of Mycobacterium tuberculosis and M . leprae were constructed in 1985 . However, there are still pitfalls for the unwary . Most of the problems associated with the use of molecular techniques to study mycobacteria can be related to one of the following problems: slow growth rate causing problems with contamination; the formation of macroscopic clumps when grown in culture; resistance to standard chemical lysis procedures; the requirement for containment facilities for pathogenic species; the lack of suitable genetic vectors; and the problems of spontaneous antibiotic resistance . Despite these problems, considerable progress has been made and standard techniques have been developed for the preparation of protein, nucleic acids (DNA and RNA) and cell wall components, chemical and transposon mutagenesis and gene replacement methods, the use of reporter genes and expression vectors, and improved detection and drug sensitivity testing.

Mol Ther, 2000 Mar, 1(3), 236 - 43
Targeted delivery of plasmid DNA to myogenic cells via transferrin-conjugated peptide nucleic acid; Liang KW et al.; We describe a novel approach to conjugate a targeting ligand to plasmid DNA without affecting either its supercoiled conformation or its ability to be efficiently transcribed . A 14-mer peptide nucleic acid (PNA) containing lysine and cysteine on each end was designed to target to a unique sequence located at the antibiotic resistance gene of the plasmid . The binding of PNA to the plasmid was found to be dose-dependent and sequence-specific and not to change the conformation of the plasmid . Transferrin (Tf) was conjugated with PNA via a reversible disulfide bond using N-succinimidyl-3-(2-pyridyldithio)propionate . Tf-PNA retained the ability to the plasmid in a sequence-specific manner . The efficiency of this bioconjugate for delivering plasmid was examined in cultured myoblasts and myotubes . Naked DNA and Tf-PNA/DNA showed no transfection activity in either myoblasts or myotubes . Polyethyleneimine (PEI) is required for significant increase of the transfection efficiency . At N:P ratio of 5, Tf-PNA enhanced gene transfection about fourfold over that of the DNA/PEI complex in both myoblasts and myotubes . This enhancement could be inhibited by excess free Tf, indicating that the enhancement of transfection was through Tf-mediated endocytosis . These findings suggest that this targeting system may have the potential for gene transfer to myogenic cells in vivo.

Microbiology, 2000 Aug, 146 ( Pt 8), 1969 - 75
Use of a flexible cassette method to generate a double unmarked Mycobacterium tuberculosis tlyA plcABC mutant by gene replacement; Parish T et al.; Progress in the field of mycobacterial research has been hindered by the inability to readily generate defined mutant strains of the slow-growing mycobacteria to investigate the function of specific genes . An efficient method is described that has been used to generate several mutants, including the first double unmarked deletion strain of Mycobacterium tuberculosis . Four mutants were constructed: a marked deletion of the plcABC cluster, which encodes three phospholipases C; separate unmarked deletions in plcABC and tlyA (encoding a haemolysin); and a double unmarked mutant tlyADelta plcABCDelta . To accomplish this, two series of vectors were designed, the first of which, named pNIL, allows manipulation of the target gene sequence at a variety of convenient restriction sites . The second series, named pGOAL, contains marker cassettes flanked by PAC:I restriction enzyme sites . The final suicide plasmid vectors were then obtained by cloning a marker cassette from a pGOAL vector into the single PAC:I site of the pNIL vector with the modified gene of interest . Finally, a two-step strategy was employed whereby single cross-over events were first selected, then screening for the second cross-over was carried out to yield the mutant strains . This technique will now allow the construction of potential vaccine strains without the inclusion of antibiotic resistance markers, the ability to make multiple defined mutations and the possibility of making more subtle defined mutations, such as point mutations.

J R Soc Health, 2000 Mar, 120(1), 52 - 3
Botanical perspectives on health: of cystitis and cranberries; Patel N et al.; With generalised increased use of antibiotics there has been the accompanying development of antibiotic resistance . It has been suggested that the therapy of uncomplicated cystitis is one area in which it is possible to reduce the usage of such compounds . Many women have long drunk cranberry juice--and it has become an 'old-wives' tale in the treatment of this infection . Perhaps it is now time for science to investigate further the benefits of the humble cranberry.

Int J Cancer, 2000 Aug 15, 87(4), 559 - 68
A3--a novel colon and pancreatic cancer reactive antibody from a primate phage library selected using intact tumour cells; Tordsson J et al.; The identification of novel tumour-associated antigens (TAAs) is pivotal for progression in the fields of tumour immunotherapy and diagnosis . In the present study, we have developed, based on flow cytometric evaluation and use of a mini-library composed of specific antibody clones linked to different antibiotic resistance markers, methods for positive and subtractive selection of phage antibodies employing intact cells as the antigen source . An scFv phage library (2.7 x 10(7)) was constructed from a primate (Macaca fascicularis) immunised with pooled human colon carcinomas . This library was selected for 3 rounds by binding to Colo 205 colon adenocarcinoma cells and proteolytic elution followed by phage amplification . Several antibodies reactive with colon carcinomas and with restricted reactivity to a few epithelial normal tissues were identified by immunohistochemistry . One clone, A3 scFv, recognised an epitope that was homogeneously expressed in 11/11 of colon and 4/4 pancreatic carcinomas studied and in normal tissue restricted to subtypes of epithelia in the gastrointestinal tract . The A3 scFv had an apparent overall affinity approximately 100-fold higher than an A3 Fab, suggesting binding of scFv homodimers . The cell surface density of the A3 epitope, calculated on the basis of Fab binding, was exceptionally high, approaching 3 million per cell . We also demonstrate efficient T-cell-mediated killing of colon cancer cells coated with A3 scFv fused to the low MHC class II binding superantigen mutant SEA(D227A) . The identified A3 molecule thus represents a TAA with properties that suggest its use for immunotherapy of colon and pancreatic cancer .

Mil Med, 2000 Jul, 165(7 Suppl 2), 35 - 9
The state of antibiotic resistance surveillance: an overview of existing activities and new strategies; Davis SR; The growing global problem of antibiotic resistance requires a worldwide surveillance strategy to characterize the magnitude of the problem, guide clinical care decisions, and assess the impact of prevention and control interventions . Because many existing antibiotic resistance surveillance activities have developed independently of one another and vary greatly in their focus, key organizations are promoting strategies to standardize surveillance activities and build collaboration to promote effective global surveillance . With medical facilities operating throughout the world to support a highly mobile beneficiary population, the Department of Defense's Military Health System could benefit from partnership with civilian efforts to achieve global antibiotic resistance surveillance . This article's overview of existing surveillance activities and new strategies provides information requisite to the Department of Defense undertaking of development of a worldwide antibiotic resistance surveillance program to complement and integrate with civilian programs.

Mil Med, 2000 Jul, 165(7 Suppl 2), 25 - 7
Bioterrorism and the importance of the public health laboratory; Pavlin JA; Biological terrorism is a threat to the United States that public health laboratories cannot afford to ignore . With the ability to recognize unusual strains of organisms, or an increase in test requests or isolation of specific organisms, the public health laboratory can detect the beginning of an outbreak . The laboratory can also facilitate appropriate response measures with rapid diagnostic testing and by determining antibiotic resistance patterns . Public health laboratory personnel need to assess their capabilities, improve them where indicated, and know where to turn for assistance . As improvements in bioterrorism detection occur in the civilian sector, military laboratories must integrate with local, state, and federal health department systems . Laboratories are essential components in surveillance, recognition, and response for both bioterrorism and naturally occurring disease outbreaks.

Mil Med, 2000 Jul, 165(7 Suppl 2), 5 - 7
The need for a military public health laboratory symposium; Gaydos JC; The Department of Defense Global Emerging Infections Surveillance and Response System has a mission to identify vulnerabilities in the military health system related to the occurrence of emerging infectious diseases . Public health laboratory (PHL) functions are critical to the detection and control of emerging infectious diseases and were assessed . Four important services were evaluated: (1) surveillance for antibiotic resistance, (2) laboratory-based infectious disease surveillance, (3) provision of diagnostic services for uncommon infections, and (4) specimen referral and information transfer within a defined PHL infrastructure . Initial assessments identified several shortcomings and a lack of information about PHL functions . Therefore, a PHL symposium was held in September 1999 to define the state of civilian and military PHL functions, identify problems and interventions, and encourage civilian-military networking . After the symposium, selected attendees met in two workshop groups . One addressed the first two functions; the other addressed the last two.

J Infect Dis, 2000 Aug, 182(2), 517 - 25 Epub 2000 Jul 24.
Selection of antibiotic-resistant bacterial mutants: allelic diversity among fluoroquinolone-resistant mutations; Zhou J et al.; To obtain a general framework for understanding selection of antibiotic-resistant mutants, allelic diversity was examined with about 600 fluoroquinolone-resistant mutants of mycobacteria . Selection at low fluoroquinolone concentration produced many low-level resistance mutants . Some of these contained mutations that conferred unselected antibiotic resistance; none contained alterations in the quinolone-resistance-determining region of the GyrA protein, the principal drug target . As selection pressure increased, a variety of GyrA variants became prevalent . High concentrations of antibiotic reduced the variety to a few types, and eventually a concentration was reached at which no mutant was recovered . That concentration defined a threshold for preventing the selection of resistance . The pattern of variants selected, which was also strongly influenced by antibiotic structure, readily explained the variants present in clinical isolates . Thus, resistance arises from selection of mutants whose identity depends on drug concentration and structure, both of which can be manipulated to restrict selection.

Anesteziol Reanimatol, 2000 May-Jun, (3), 64 - 9
{Sepsis on the threshold of the 21st century: the basic results . New problems and the immediate tasks}; Rudnov VA et al.; The authors validate their positions in terminology of sepsis and evaluation of its severity, based on analysis of this problem evolution during the century, review of the most significant publications, and their own findings . Problems of intensive care are discussed . The authors claim that intensive care methods should be determined by the phase of the systemic inflammatory response syndrome (SIRS) . One of the nearest goals for scientists and public health managers is an interdisciplinary consensus on terminology of sepsis and diagnostic criteria, creation of a standard protocol of laboratory studies and treatment, search for available markers of SIRS of infectious origin, regulation of cytokine response, creation of local data bases reflecting the etiological structure of the agents and their antibiotic resistance.

Antimicrob Agents Chemother, 2000 Aug, 44(8), 2214 - 6
Regional differences in metronidazole resistance and increasing clarithromycin resistance among Helicobacter pylori isolates from Japan; Kato M et al.; The patterns of antibiotic resistance in Helicobacter pylori were assessed in two different regions in Japan . Overall, prevalences of resistance to metronidazole and clarithromycin were 12.4 and 12.9%, respectively . While there was no difference in clarithromycin resistance, the prevalence of metronidazole resistance was significantly higher in Kyoto (23.8%) than in Sapporo (8.1%) . From 1996 to 1999, the prevalence of metronidazole resistance did not change but the prevalence of clarithromycin resistance doubled (from 9.1 to 18.7%).

J Gen Intern Med, 2000 Jun, 15(6), 400 - 10
Cost-effectiveness of strategies for primary prevention of nonsteroidal anti-inflammatory drug-induced peptic ulcer disease; Ko CW et al.; OBJECTIVE: Nonsteroidal anti-inflammatory drugs (NSAIDs) increase the risk of peptic ulcer disease by 5- to 7-fold in the first 3 months of treatment . This study examined the relative cost-effectiveness of different strategies for the primary prevention of NSAID-induced ulcers in patients that are starting NSAID treatment . MEASUREMENTS AND MAIN RESULTS: A decision analysis model was developed to compare the cost-effectiveness of 6 prophylactic strategies relative to no prophylaxis for patients 65 years of age starting a 3-month course of NSAIDs: (1) testing for Helicobacter pylori infection and treating those with positive tests; (2) empiric treatment of all patients for Helicobacter pylori; (3) conventional-dose histamine2 receptor antagonists; (4) high-dose histamine2 receptor antagonists; (5) misoprostol; and (6) omeprazole . Costs were estimated from 1997 Medicare reimbursement schedules and the Drug Topics Red Book . Empiric treatment of Helicobacter pylori with bismuth, metronidazole, and tetracycline was cost-saving in the baseline analysis . Selective treatment of Helicobacter pylori, misoprostol, omeprazole, and conventional-dose or high-dose histamine2 receptor antagonists cost $23,800, $46,100, $34,400, and $15,600 or $21,500 per year of life saved, respectively, relative to prophylaxis . The results were sensitive to the probability of an ulcer, the probability and mortality of ulcer complications, and the cost of, efficacy of, and compliance with prophylaxis . The cost-effectiveness estimates did not change substantially when costs associated with antibiotic resistance of Helicobacter pylori were incorporated . CONCLUSIONS: Several strategies for primary prevention of NSAID-induced ulcers in patients starting NSAIDs were estimated to have acceptable cost-effectiveness relative to prophylaxis . Empirically treating all patients for Helicobacter pylori with bismuth, metronidazole, and tetracycline was projected to be cost-saving in older patients.

Philos Trans R Soc Lond B Biol Sci, 2000 May 29, 355(1397), 587 - 99
Detection and analysis of gene expression during infection by in vivo expression technology; Merrell DS et al.; Many limitations associated with the use of in vitro models for study of bacterial pathogenesis can be overcome by the use of technologies that detect pathogen gene expression during the course of infection within an intact animal . In vivo expression technology (IVET) accomplishes this with versatility: it has been developed with a variety of reporter systems which allow for either in vivo selection or ex vivo screening . Selectable gene fusion systems generally allow for the complementation of a bacterial metabolic defect that is lethal in vivo, or for antibiotic resistance during the course of in vivo antibiotic challenge . In contrast, the screenable gene fusion system uses a site-specific DNA recombinase that, when expressed in vivo, excises a selectable gene cassette from the bacterial chromosome . Loss of this cassette can then be either screened or selected for ex vivo . The recombinase-based IVET can be used to detect genes that are transcriptionally induced during infection, including those expressed transiently or at low levels and, in addition, can be used to monitor the spatial and temporal expression of specific genes during the course of infection.

J Periodontol, 2000 May, 71(5), 768 - 74
The effects of sustained release doxycycline on the anaerobic flora and antibiotic-resistant patterns in subgingival plaque and saliva; Walker CB et al.; BACKGROUND: The purpose of this study was to determine the effects of periodontal treatment with a sustained-release, biodegradable gel containing 8.5% doxycycline on the anaerobic flora and on antibiotic susceptibility patterns associated with subgingival plaque and saliva . METHODS: Forty-five subjects with adult periodontitis were entered into a parallel design, single-blind study of 6 months' duration . The subjects were randomized to receive either doxycycline treatment (n = 23) or oral hygiene instruction/reinforcement (n = 22) . Saliva and subgingival plaque samples were collected prior to and at 7, 21, 91, and 182 days after initiation of treatment . The proportion of the cultivable flora resistant to 10 microg doxycycline/ml was determined relative to total anaerobic counts, and the 3 most predominant colony types resistant to doxycycline were individually enumerated . A representative of each was subcultured, identified to genus and species level, and tested for its susceptibilities to 6 antibiotics . RESULTS: A significant decrease (P <0.01) in total anaerobic counts following doxycycline treatment caused a transient increase in the proportion, but not in the actual counts, of doxycycline-resistant bacteria recovered from both plaque and saliva at 7 and 21 days but not at 91 or 182 days . The same doxycycline-resistant taxa were recovered at all sample periods including baseline . Regardless of treatment, the isolates were similarly distributed and belonged to the same bacterial groups . CONCLUSIONS: Doxycycline treatment significantly reduced the anaerobic population in plaque but did not result in a change in either the number of resistant bacteria present or the acquisition of antibiotic resistance.

J Infect Dis, 2000 Jun, 181 Suppl 3, S394 - 401
Chlamydia pneumoniae and cardiovascular disease: an evolutionary perspective on infectious causation and antibiotic treatment; Ewald PW et al.; Evolutionary considerations implicate infectious causation of atherosclerosis and help to resolve different risk factors as parts of an overall process of disease causation . An evolutionary approach also provides insight for the timing of research efforts to provide better control of pathogen evolution . In particular, evolutionary considerations emphasize the need to understand the transmissibility of Chlamydia pneumoniae from systemic infections in order to control the evolution of antibiotic resistancePublication Types:

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