Adv Perit Dial, 1997, 13, 214 - 7 The effects of macrolide and quinolone antibiotics in methicillin-resistant Staphylococcus aureus biofilm growth; Dasgupta MK et al.; Recent studies demonstrate that 14-membered macrolides increase permeability and destruction of Pseudomonas biofilms . The effect of a macrolide antibiotic, erythromycin, on methicillin-resistant Staphylococcus aureus (MRSA) biofilm on Silastic catheter materials in comparison with two different quinolone antibiotics, sparfloxacin (SPFX) and a new quinolone, SYN 1193, was examined . Two different MRSA strains were grown in biofilm, using Mueller-Hinton broth with and without the addition of 10% pooled normal human serum (PNHS), in a modified Robbins device, at 37 degrees C for 24, 48, and 72 hours . Two different clinical MRSA strains were used and minimum bactericidal concentration (MBC) were determined at the time intervals mentioned . Three different dosages of each antibiotic were tested: 5.0, 20.0, and 50.0 micrograms/mL . In addition, a constant dosage of SPFX and SYN 1193, in combination with varying dosages of erythromycin, was tested under similar experimental conditions . SYN 1193 demonstrated the highest MBC in comparison to SPFX; addition of PNHS did not alter the effect of SYN 1193 . However, erythromycin alone and in combination with SPFX and SYN 1193 had no effect on MBC . We conclude that (1) macrolide antibiotic erythromycin has poor MRSA biofilm permeability and killing in comparison to SPFX and SYN 1193, and (2) SYN 1193 had the highest MBC to MRSA biofilm. Sci Total Environ, 1997 Oct 7, 205(1), 25 - 49 Nutrient dynamics in a lowland stream impacted by sewage effluent: Great Ouse, England; House WA et al.; Nutrient and ancillary chemical changes in a stretch of the Great Ouse river near Brackley in Northamptonshire, UK, were measured on a seasonal basis over one year with an initial pilot study in the spring of 1994 . River bed-sediments were characterized by their physical, adsorptive and chemical properties and a batch returned to the laboratory for experiments in a fluvarium channel . These experiments involved studies of the release and uptake of soluble reactive phosphorus to or from the overlying water in oxic conditions and release when the dissolved oxygen concentration was reduced to near zero . There was no impact of the point-sources on the concentration of nitrate in the river, a slight effect on the concentration of silicon during low-flow conditions in the summer and net uptake in the spring caused by the growth of diatoms . However there was a substantial impact on phosphorus concentrations, particularly during the summer sampling when the river was in low flow . The results for the winter showed little impact of point discharges because of the high dilution of the treated effluent . The bed-sediments at this time were found to be close to equilibrium with respect to the concentration of soluble reactive phosphorus in the overlying water . Both the fluvarium channel and field measurements obtained in the autumn are consistent with a lower net uptake of phosphorus and degradation of vegetation in the river . In the spring and summer visits, the phosphorus concentrations increased immediately downstream of the main point input and then decreased in concentration at the next downstream site . This effect was particularly noticeable in the summer and was consistent with a large uptake of phosphorus to the bed-sediment and associated vegetation . The contribution of the bed-sediment was estimated using a chemical model describing the uptake kinetics by the Elovich equation and also a parabolic equation . The stability of the waters with respect to calcite and calcium phosphate minerals was assessed in detail . Seasonal changes in the sediment composition were consistent with the deposition of calcite and coprecipitation of inorganic phosphate in the lattice of calcite, either abiotically, or in association with algal biofilms in the sediment . Good correlation between the total phosphorus and calcium contents of the sediments were evident, particularly at the sites furthest from the main sewage input . Measurements of the equilibrium phosphate concentrations of the surface sediments showed that they did not respond quickly to the higher concentrations of dissolved phosphorus found in the summer . It is also evident that the use of the equilibrium phosphate concentration to predict the magnitude of the release of soluble reactive phosphorus becomes less reliable as the solution concentration approaches the equilibrium phosphate concentration . Perturbations may arise because of changes in the surface micro-layer caused by a number of processes such as particle-size fractionation, biological activity or changes in the local redox conditions . However bearing these constraints in mind, with an equilibrium phosphate concentration of the sediments generally below 5 mumol dm-3, the release of phosphorus to the overlying water is not expected until the concentration is below this value . The results also show that phosphorus is not accumulating in the surface sediment and that much of the phosphorus in the sediment is not easily desorbed. J Comp Pathol, 1997 Aug, 117(2), 165 - 70 Adaptation of a fluorocarbon-based non-aqueous fixation regime for the ultrastructural study of the teleost epithelial mucous coat; Sanchez JG et al.; Studies on the microanatomy of the mucus-rich biofilm surface of normal or damaged teleost skin tissue have been limited because conventional fixation regimes do not effectively retain mucus during tissue preparation . A non-aqueous fixation method, based on a technique devised to retain airway mucous for ultrastructural study, and consisting of the use of an inert perfluorocarbon solvent with osmium teroxide 1%, was successfully used to prepare skin tissues of healthy juvenile rainbow trout . The skin's mucous coat was examined by transmission electron microscopy and the results were compared with those obtained with tissues prepared by a conventional glutaraldehyde-based method . In samples fixed with glutaraldehyde, the cell-surface structures retained were limited to microridges and a poorly discernible glycocalyx layer . In contrast, those fixed by the non-aqueous method had a more clearly demonstrated glycocalyx layer, and a second fibrillar layer, resembling mucus, which was separated from the glycocalyx layer by an electron-lucent zone. Appl Environ Microbiol, 1997 Oct, 63(10), 4107 - 10 Magnification of tributyl tin toxicity to oyster larvae by bioconcentration in biofilms of Shewanella colwelliana; Labare ML et al.; The toxic effects of dissolved versus bioconcentrated tributyl tin (TBT) on oyster larvae were compared . Water column TBT levels, which had no effect in solution, inhibited natural attachment and metamorphosis of oyster larvae on bottom surfaces due to bioconcentration by biofilms . This mechanism should be considered when evaluating heavy metal toxicity in the environment. J Antimicrob Chemother, 1997 Sep, 40(3), 419 - 21 Antibacterial efficacy of tobramycin against anaerobic Escherichia coli cultures in the presence of electron acceptors; Tresse O et al.; The antimicrobial activity of tobramycin against anaerobic cultures of Escherichia coli was tested in the presence of various electron carriers . The presence of 2,6-dichlorophenol 4-indophenol (DCIP) significantly enhanced the killing efficacy of tobramycin . Only 0.003% of the initial cell population (i.e . 10(6) cfu/mL) remained viable after exposure for 10 h to the mixture of antibiotic (20 x MIC, i.e . 40 mg/L) and electron acceptor (10(-3) M), as compared with 9% of surviving organisms in the presence of tobramycin alone . Less synergy was obtained with p-benzoquinone and 1,2-naphthoquinone . Fumarate did not affect the efficiency of the antibiotic . The mixture of tobramycin and DCIP was ineffective against agar-entrapped bacteria which, like biofilm organisms, are subject to oxygen limitation. J Antimicrob Chemother, 1997 Sep, 40(3), 329 - 34 The development of a small-scale biofilm model suitable for studying the effects of antibiotics on biofilms of gram-negative bacteria; Gander S et al.; A method for the study of membrane-associated biofilm populations of Escherichia coli ATCC 8739 using modified Swinnex filter units was developed . Biofilms were established under carbon limitation in a chemically defined simple salts medium . Cells, pressure filtered on to cellulose nitrate membranes in situ, were perfused from the sterile side . Steady-state conditions were attained at which the growth rate of the sessile cells could be demonstrated to be proportional to the flow rate of medium . The antibiotic susceptibility of these biofilms was examined by including ciprofloxacin within the perfusing medium . Susceptibility of the biofilms to ciprofloxacin was found to be affected not only by its concentration, but also by the growth rate of the bacteria. Clin Microbiol Rev, 1997 Oct, 10(4), 597 - 610 Uses of inorganic hypochlorite (bleach) in health-care facilities; Rutala WA et al.; Hypochlorite has been used as a disinfectant for more than 100 years . It has many of the properties of an ideal disinfectant, including a broad antimicrobial activity, rapid bactericidal action, reasonable persistence in treated potable water, ease of use, solubility in water, relative stability, relative nontoxicity at use concentrations, no poisonous residuals, no color, no staining, and low cost . The active species is undissociated hypochlorous acid (HOCl) . Hypochlorites are lethal to most microbes, although viruses and vegetative bacteria are more susceptible than endospore-forming bacteria, fungi, and protozoa . Activity is reduced by the presence of heavy metal ions, a biofilm, organic material, low temperature, low pH, or UV radiation . Clinical uses in health-care facilities include hyperchlorination of potable water to prevent Legionella colonization, chlorination of water distribution systems used in hemodialysis centers, cleaning of environmental surfaces, disinfection of laundry, local use to decontaminate blood spills, disinfection of equipment, decontamination of medical waste prior to disposal, and dental therapy . Despite the increasing availability of other disinfectants, hypochlorites continue to find wide use in hospitals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 1997 Sep, 84(3), 310 - 4 Coronal leakage of mixed anaerobic bacteria after obturation and post space preparation; Barrieshi KM et al.; OBJECTIVES: The purpose of this study was to assess bacterial leakage of a mixed anaerobic community of organisms in obturated canals after post space preparation . STUDY DESIGN: A mixed microbial community of strict anaerobic organisms (F . nucleatum, P . micros and C . rectus) was developed . With the use of an in vitro model system, coronal leakage was assessed in 40 anterior teeth after obturation and post space preparation . The specific leakage time in days for each organism to penetrate through the obturating material was determined . In addition, colonization of the apical canal space was assessed by scanning electron microscope after longitudinal splitting of randomly selected specimens . RESULTS: Eighty percent of the teeth demonstrated coronal leakage of F . nucleatum and C . rectus by the 90 day interval . Bacterial penetration occurred from 48 days to 84 days . Scanning electron microscope examination showed a heterogeneous biofilm of coccal and bacillary species colonizing the apical portion of the canal wall . CONCLUSIONS: This study demonstrated that coronal leakage phenomena do occur after loss of coronal seals . The model system developed using mixed, anaerobic bacterial cultures is more clinically relevant and may be used to assess bacterial penetration through gutta percha obturation. FEMS Microbiol Lett, 1997 Sep 15, 154(2), 259 - 63 Evidence of autoinducer activity in naturally occurring biofilms; McLean RJ et al.; N-Acyl homoserine lactone (AHL) molecules have been shown to act as mediators of population density-dependent (quorum-sensing) gene expression in numerous Gram-negative bacteria . Functions associated with AHL include light production in Vibrio fischeri, expression of virulence factors in Pseudomonas aeruginosa, and conjugation in Agrobacterium tumefaciens . In nature, bacteria often grow as surface-adherent biofilm communities . As biofilms typically contain high concentrations of cells, AHL activity and quorum-sensing gene expression have been proposed as essential components of biofilm physiology . However, proof of AHL production within biofilms has heretofore been lacking . In this study we have employed a cross-feeding assay, using A, tumefaciens A136 (traI::lacZ) as an AHL-responsive reporter strain, to show the presence of naturally occurring AHL production in aquatic biofilms growing on submerged stones . AHL was detected in living biofilms and biofilm extracts, but was not present in rocks lacking a biofilm . This represents the first report of AHL activity in naturally occurring biofilms. Int J Food Microbiol, 1997 Jul 22, 37(2-3), 145 - 53 Adherence to stainless steel by foodborne microorganisms during growth in model food systems; Hood SK et al.; Biofilm formation on stainless steel by Salmonella typhimurium, Listeria monocytogenes, Escherichia coli O157:H7, Pseudomonas fragi and Pseudomonas fluorescens during growth in model food systems was studied . Test growth media included tryptic soy broth (TSB), diluted TSB (dTSB), 1% reconstituted skim milk (RSM) and diluted meat juice (DMJ) . Adherent cells were stained with acridine orange and enumerated using epifluorescent microscopy and computerized image analysis . Cells were observed on the stainless steel surface after 1 h in all of the media . However, the increases in the number of adherent cells over time was seen only with S . typhimurium in DMJ, E . coli O157:H7 in TSB, dTSB and DMJ, P . fragi in RSM and P . fluorescens in RSM . The medium which produced the highest observed level of adherent cells was different for each microorganism. Chemotherapy, 1997 Sep-Oct, 43(5), 340 - 5 Permeation of antimicrobial agents through Pseudomonas aeruginosa biofilms: a simple method; Shigeta M et al.; In this study, we evaluated the permeation of piperacillin (PIPC), imipenem (IPM), amikacin (AKM), gentamicin (GM), ofloxacin (OFLX), levofloxacin (LVFX), ciprofloxacin (CPFX) and sparfloxacin (SPFX) through Pseudomonas aeruginosa biofilm with a simple new method . Bacteria used were a leucine-requiring mucoid mutant . Bacteria were grown on the membrane of a cell culture insert in chemically defined medium and incubated at 37 degrees C for 5 days . At days 0, 1, 3 and 5, the penetration rates through the biofilms were measured . PIPC and IPM demonstrated relatively high permeation both with penetration rates at day 5 of 50%, whereas AMK and GM, which are aminoglycosides, showed low permeation both with penetration rates after day 1 of less than 25% . Among the 4 fluoroquinolones, LVFX and SPFX demonstrated excellent permeation with penetration rates that reached 100% from day 0 to 5, while OFLX and CPFX showed almost the same permeation as IPM . This method of measuring penetration rates of antimicrobial agents through biofilm is very simple and useful for the evaluation of antibiotics against biofilm-forming bacteria. Curr Microbiol, 1997 Oct, 35(4), 249 - 54 Enzyme-linked lectinsorbent assay measures N-acetyl-D-glucosamine in matrix of biofilm produced by Staphylococcus epidermidis; Thomas VL et al.; An enzyme-linked lectinsorbent assay (ELLA) was developed for quantification of in situ biofilm produced by Staphylococcus epidermidis in polystyrene 96-well tissue culture plates with phosphatase-labeled wheat germ agglutinin (WGA) as a specific probe for the GlcNAcbeta-1,4n component of exocellular matrix material (EMM) that is responsible for intercellular adhesion and accumulation . The ELLA and the modified Christensen dye assay were used to test 13 laboratory strains of coagulase-negative staphylococci and 10 clinical isolates of S . epidermidis . Four biofilm-positive laboratory strains of S . epidermidis were positive by both tests, and six biofilm-negative strains were negative by both . One strain of S . hemolyticus was positive by the ELLA only . Two of the 10 clinical isolates of S . epidermidis were positive by both assays, two were negative by both, and the remaining were positive by the ELLA only . The ELLA was objective, reproducible, specific, sensitive, and useful for screening strains for their capacity to adhere to plastic, produce EMM, and form biofilm. Behring Inst Mitt, 1997 Feb, (98), 350 - 60 Rationale for development of immunotherapies that target mucoid Pseudomonas aeruginosa infection in cystic fibrosis patients; Pier GB; Despite a complex sputum bacteriology, the progressive decline in pulmonary function that is the hallmark of the genetic disease cystic fibrosis (CF) is attributable to a single infecting pathogen, mucoid Pseudomonas aeruginosa . Therefore, active and passive immunotherapies that target this particular variant of the bacterium should be of value in attenuating infection and interfering with the decline in pulmonary function . The major surface antigen of mucoid P . aeruginosa is referred to as either mucoid exopolysaccharide (MEP) or alginate, a random polymer of D-mannuronic and L-guluronic acid residues linked beta 1-4 . During chronic infection CF patients make antibodies to MEP that fail to mediate opsonic killing of bacteria in vitro . These antibodies can be elicited by vaccination in 35-40% of plasma donors given a preparation of MEP comprised of only the highest molecular-weight polymers; inclusion in human vaccines of smaller polymers normally produced by the bacterium fails to elicit opsonic antibodies, just like in infected CF patients . Opsonic, but not non-opsonic, antibodies to MEP protect animals against chronic endobronchial infection . CF patients do produce opsonic antibodies to mucoid P . aeruginosa that are in a planktonic or suspended state, but these antibodies are not directed at the MEP antigen and they fail to kill P . aeruginosa growing in a biofilm . This is the state that the bacteria grow in the lung . Therefore immunoglobulin G preparations with opsonic antibodies to MEP could provide CF patients with antibodies that they normally do not produce during chronic lung infection and may improve their clinical course. Can J Microbiol, 1997 Aug, 43(8), 751 - 8 Influence of trophic conditions on exopolysaccharide production: bacterial biofilm susceptibility to chlorine and monochloramine; Samrakandi MM et al.; This study examines the controversial efficacy of chlorine and monochloramine against biofilms that differ in their extracellular polysaccharide (EPS) content . The results point out a net variability of bacterial biofilm susceptibility according to the nutrients present . Chlorine and monochloramine showed an equal biocidal activity on lactose medium-grown E . coli ATCC 10536 and glycerol-ammonium nitrate medium-grown nonmucoid Pseudomonas aeruginosa biofilms . In contrast, the effect of monochloramine is greater compared with that of chlorine on E . coli and mucoid P . aeruginosa biofilms grown in sucrose and glycerol-ammonium nitrate media, respectively . In these culture conditions, treatment with 25 mg monochloramine/L for 2 h reduced culturable cells by 4.5 logs (99.997%) for E . coli and about 3 logs (99.87%) for mucoid P . aeruginosa while the similar treatment with chlorine reduced culturable cells in these biofilms by 2.2 logs (99.4%) and 1 log (10%), respectively . The decrease of chlorine disinfection efficacy on sucrose and glycerol-ammonium nitrate medium-grown biofilms is postulated to be linked to the higher polysaccharide production observed in these media . It seems likely that monochloramine produces a high leakage of material absorbing at 260 nm from sucrose medium-grown E . coli biofilm, which could indicate its better penetration into biofilms. Antimicrob Agents Chemother, 1997 Sep, 41(9), 1876 - 9 Influence of electric fields and pH on biofilm structure as related to the bioelectric effect; Stoodley P et al.; Mixed species biofilms of Klebsiella pneumoniae, Pseudomonas fluorescens, and Pseudomonas aeruginosa were grown in a flow cell fitted with two platinum wire electrodes . The biofilm growing on the wires reached a thickness of approximately 50 microm after 3 days . When a voltage was applied with oscillating polarity, the biofilm attached to the wire expanded and contracted . The biofilm expanded by approximately 4% when the wire was cathodic but was reduced to 74% of the original thickness when the wire was anodic . The phenomenon was reproduced by alternately flushing the flow cell with media adjusted to pH 3 and pH 10 with no electric current . At pH 10 the biofilm was unaltered, but it became compacted to 69% of the original thickness at pH 3 . We explained these phenomena in terms of the molecular interactions between charged acidic groups in the biofilm slime and the bacterial cell walls . Contraction of the biofilm under acidic conditions may be caused by (i) the elimination of electrostatic repulsion from neutralization of negatively charged carboxylate groups through protonation and (ii) subsequent hydrogen bonding between the carboxylic acids and oxygen atoms in the sugars . Electrostatic interactions between negatively charged groups in the biofilm and the charged wire may also be expected to cause biofilm expansion when the wire was cathodic and contraction when the wire was anodic . The consequences of the explanation of the increased susceptibility of biofilm cells to antibiotics in an electric field, the "bioelectric effect," are discussed. FEMS Microbiol Rev, 1997 Jul, 20(3-4), 573 - 90 Microbial studies in the Canadian nuclear fuel waste management program; Stroes-Gascoyne S et al.; Atomic Energy of Canada Limited (AECL) has developed a concept for permanent geological disposal of used nuclear fuel in Canada . This concept, based on a multibarrier system, would involve disposal of nuclear fuel waste in titanium or copper containers, surrounded by compacted clay-based buffer and backfill materials, in a vault 500-1000 m deep in granitic rock of the Canadian Shield . Subsurface environments will not be sterile and an experimental program was initiated in 1991 by AECL to address and quantify the potential effects of microbial action on the integrity of the disposal vault . This microbial program focuses on answering specific questions in areas such as the survival of bacteria in compacted clay-based buffer materials under relevant radiation, temperature and desiccation conditions; mobility of microbes in compacted buffer materials; the potential for microbially influenced corrosion of containers; microbial gas production in backfill material; introduction of nutrients as a result of vault excavation and operation; the presence and activity of microbes in deep granitic groundwaters; and the effects of biofilms on radionuclide migration in the geosphere . This paper summarizes the results to date from the research activities at AECL. FEMS Microbiol Rev, 1997 Jul, 20(3-4), 291 - 303 Interactions between biofilms and the environment; Beveridge TJ et al.; The surfaces of bacteria are highly interactive with their environment . Whether the bacterium is Gram-negative or Gram-positive, most surfaces are charged at neutral pH because of the ionization of the reactive chemical groups which stud them . Since prokaryotes have a high surface area-to-volume ratio, this can have surprising ramifications . For example, many bacteria can concentrate dilute environmental metals on their surfaces and initiate the development of fine-grained minerals . In natural environments, it is not unusual to find such bacteria closely associated with the minerals which they have helped develop . Bacteria can be free-living (planktonic), but in most natural ecosystems they prefer to grow on interfaces as biofilms; supposedly to take advantage of the nutrient concentrative effect of the interface, although there must also be gained some protective value against predators and toxic agents . Using a Pseudomonas aeruginosa model system, we have determined that lipopolysaccharide is important in the initial attachment of this Gram-negative bacterium to interfaces and that this surface moiety subtly changes during biofilm formation . Using this same model system, we have also discovered that there is a natural tendency for Gram-negative bacteria to concentrate and package periplasmic components into membrane vesicles which bleb-off the surface . Since some of these components (e.g., peptidoglycan hydrolases) can degrade other surrounding cells, the vesicles could be predatory; i.e., a natural system by which neighboring bacteria are targeted and lysed, thereby liberating additional nutrients to the microbial community . This obviously would be of benefit to vesicle-producing bacteria living in biofilms containing mixed microbial populations. J Am Dent Assoc, 1997 Sep, 128(9), 1235 - 43 Comparison of dental water quality management procedures; Murdoch-Kinch CA et al.; The effectiveness of ADA-recommended approaches for reducing dental unit waterline, or DUWL, contamination was investigated using newly installed dental units . Over a 2-month period, the authors studied independent water reservoirs, a sodium hypochlorite disinfection regimen, daily draining and purging of DUWLs and point-of-use filters by assessing microbial contamination and biofilm development using scanning electron microscopy . The findings demonstrate that DUWL contamination can be controlled when dental personnel use available technologies and adhere to recommended maintenance protocols. Arch Oral Biol, 1997 Jul, 42(7), 513 - 20 Colonization of Candida albicans on cleaned human dental hard tissues; Sen BH et al.; Candida albicans is a fungus that commonly infects oral mucosal surfaces . Limited data exist on biofilm formation by C . albicans on dental surfaces . Human premolar teeth were infected with C . albicans for 10 days and hard-tissue surfaces were examined with a scanning electron microscope . Enamel, cementum and dentine, in the absence or presence of a smear layer, were readily colonized by this micro-organism . Hyphae penetrated into cracks, followed the ridges of the cavities and migrated into dentinal tubules . Blastospores and hyphae were embedded in an extracellular material . These findings suggest that dental hard tissues may be invaded by C . albicans and thus can potentially present a reservoir for disseminating candidal infections. Appl Environ Microbiol, 1997 Sep, 63(9), 3724 - 8 Enzymatic removal and disinfection of bacterial biofilms; Johansen C et al.; Model biofilms of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas fluorescens, and Pseudomonas aeruginosa were made on steel and polypropylene substrata . Plaque-resembling biofilms of Streptococcus mutans, Actinomyces viscosus, and Fusobacterium nucleatum were made on saliva-coated hydroxyapatite . The activity of enzymes against bacterial cells in biofilm was measured by fluorescence microscopy and an indirect conductance test in which evolution of carbon dioxide was measured . Glucose oxidase combined with lactoperoxidase was bactericidal against biofilm bacteria but did not remove the biofilm from the substrata . A complex mixture of polysaccharide-hydrolyzing enzymes was able to remove bacterial biofilm from steel and polypropylene substrata but did not have a significant bactericidal activity . Combining oxidoreductases with polysaccharide-hydrolyzing enzymes resulted in bactericidal activity as well as removal of the biofilm. Appl Environ Microbiol, 1997 Sep, 63(9), 3352 - 8 Substratum topography influences susceptibility of Salmonella enteritidis biofilms to trisodium phosphate; Korber DR et al.; Established (48- and 72-h) Salmonella enteritidis biofilms grown in glass flow cells with or without artificial crevices (0.5-, 0.3-, and 0.15-mm widths) were subjected to a 10% trisodium phosphate (TSP) solution under different flow regimens (0.3, 0.6, 1.2, and 1.8 cm s-1) . The abundance of biofilm remaining after TSP treatment, the biocidal efficacy of TSP, and the factors which contributed to bacterial survival were then evaluated by using confocal laser microscopy and a fluorescent viability probe . Biofilm age affected the amount of biofilm which remained following a 15-s exposure to TSP . After TSP treatment of 48-h biofilms, 29% of the original biofilm remained at the biofilm-liquid interface, whereas 75% of the biofilm remained at the base (the attachment surface) . Following TSP treatment of 72-h biofilms, 27% of the biofilm material remained at the biofilm-liquid interface, 73% remained at the 5-micron depth, and 91% remained at the biofilm base . Results obtained using the BacLight viability probe indicated that TSP exposure killed all the cells in 48-h biofilms, whereas in the thicker 72-h biofilms, surviving bacteria (approximately 2% of the total) were found near the 5- and 0-micron depths . In the presence of artificially constructed crevices, an inverse relationship was shown to exist between bacterial survival (ranging from approximately 13 to 83% of total biofilm material) and crevice width . This relationship was further influenced by the velocity of TSP flow; high TSP flow velocities (1.8 cm s-1) resulted in the lowest number of surviving bacteria at the base of crevices (approximately 42% survival) . Extended time courses demonstrated that after TSP stress was relieved, biofilms continued to grow within crevices but not in systems without crevices . It is suggested that advective TSP flux into crevices and through the biofilm matrix was enhanced under conditions of high flow . These results suggest that the inherent roughness of the substratum on which the biofilm was grown and the timing of TSP application are important factors controlling the efficacy of TSP treatment. J Oral Rehabil, 1997 Aug, 24(8), 594 - 604 Effects of salivary or serum pellicles on the Candida albicans growth and biofilm formation on soft lining materials in vitro; Nikawa H et al.; The effects of salivary or serum pellicle on Candida albicans growth, biofilm formation and cavitation on the soft lining materials were examined . Both saliva and serum pellicles reduced the antifungal effects of soft liners . The fungal biofilm formation on these materials varied depending upon both the materials tested and protein-coats, and the pellicles which significantly enhanced the biofilm formation . Similarly, the pellicles enhanced the firm colonization and hyphal invasion of the yeasts on the specimens, although the cavitation appeared to be regulated by the plasticizer used . These results suggest that the interactions between proteinaceous pellicle, tissue conditioners and fungi are complex . They also suggest that denture pellicles facilitate fungal plaque formation onto soft lining materials through several mechanisms such as reduction of the antifungal effects of soft liners, facilitation of biofilm formation, firm colonization and hyphal invasion . In addition, the composition of the materials is also involved in the susceptibility to the fungi. Curr Microbiol, 1997 Sep, 35(3), 169 - 74 Biofouling of groundwater systems by Thiothrix spp; Brigmon RL et al.; Thiothrix spp., sulfide-oxidizing filamentous bacteria, were found to be a principal bacterial component of aquatic biofilms causing biofouling in selected municipal water storage tanks, private wells, and drip irrigation systems in Florida . Treatments of up to 200 ppm chlorine in the affected systems could not prevent return of the biofouling problem . The water originated from the upper Floridan aquifer and associated surficial aquifers in central and north Florida . Samples were examined where visible biofilms had a white, filamentous appearance, indicative of Thiothrix spp . The detection of Thiothrix spp . was confirmed by enzyme-liked immunosorbent assay (ELISA), indirect immunofluorescence (IIF), and microbiological procedures . It was estimated through immunocytochemical procedures that Thiothrix spp . comprised 18% of the biofilm in the municipal water storage tanks . These observations confirm that specific biological and chemical interactions may induce physical changes leading to significant biofouling. Spinal Cord, 1997 Aug, 35(8), 521 - 5 Urinary catheter blockage depends on urine pH, calcium and rate of flow; Burr RG et al.; Urinary catheters tend to block when biofilm from urease-producing organisms build up on the catheter surface . This is a locally-occurring process that influences and influenced by the composition of the urine . In this work we relate urine pH and calcium to catheter blockage and suggest how to reduce the rate of encrustation . Sixty patients with indwelling urinary catheters were studied, 26 of them being troubled by frequent blockage of their catheters, 34 of them not . A series of small urine samples were collected during a 24 h period . Urinary pH and calcium concentration were combined into discriminant functions designed to separate Blockers from Non-blockers and achieved a 95% correct classification . The results indicate that a high and uniform rate of fluid intake is mandatory for the patient with a tendency for catheter blockage . Excessive total fluid intake may be avoided by attention to uniformity . Other avoidable risk factors include: excess dietary calcium from certain protein supplements and antacids; excess dietary magnesium from certain beverages and antacids; alkali from effervescent tablets; excess dietary citrate from some fruit juices and cordials; intermittent dehydration from alcohol ingestion . Less tractable risk factors include infection of the urinary tract with urease-positive organisms, hypercalciuria of immobilisation, hyperhydrosis and postural oliguria . The processes involved in catheter encrustation and blockage provide a model for the formation of calculi in spinal cord injured patients . Therefore the above considerations may also be relevant to the management of stone disease in paraplegic and tetraplegic patients. Curr Eye Res, 1997 Aug, 16(8), 776 - 81 Protein-lipid interaction on the surface of a hydrophilic contact lens in vitro; Bontempo AR et al.; PURPOSE: To investigate the mechanism of protein-lipid interactions responsible for biofilm formation on the surface of hydrophilic contact lenses in vitro . METHODS: New, never-worn hydrophilic contact lenses were individually incubated in a protein-only, lipid-only, or combination protein-lipid artificial tear solution for 24 hours at 37 degrees C with constant stirring . Deposited lipids were removed with a methanol based extraction procedure, separated using high-performance, thin layer chromatography and quantitatively analyzed densitometrically . Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically . RESULTS: The presence of protein in the artificial tear solution has a profound effect on the nature of lipid deposition for each group of hydrophilic lens, whereas the presence of lipid has a significant effect on the nature of protein deposition for only a group IV lens . In addition, the presence of lipid deposits on a group IV lens decreases the adsorption of lysozyme, while the presence of protein deposits reduces the amount of total lipid adhering to a group II lens . CONCLUSIONS: Protein adsorption on a group IV lens renders the lens surface less hydrophilic and, thereby, more susceptible to lipid deposition, which in turn increases surface hydrophobicity and inhibits additional protein deposition . For a group II lens, positively charged protein competes with and replaces some of the polar lipids attached to the lens . Thus, the interaction of protein and lipid on a lens surface most prone to a particular contaminant apparently makes it less likely for that contaminant to bind. Appl Microbiol Biotechnol, 1997 Jul, 48(1), 11 - 7 Axenic aerobic biofilms inhibit corrosion of SAE 1018 steel through oxygen depletion; Jayaraman A et al.; Corrosion inhibition of SAE 1018 steel by pure-culture biofilms of Pseudomonas fragi and Escherichia coli DH5 alpha has been evaluated in complex Luria-Bertani medium, seawater-mimicking medium, and modified Baar's medium at 30 degrees C . In batch cultures, both bacteria inhibited corrosion three to six fold compared to sterile controls, and the corrosion was comparable to that observed in anaerobic sterile media . To corroborate this result, a continuous reactor and electrochemical impedance spectroscopy were used to show that both P . fragi K and E . coli DH5 alpha decreased the corrosion rate by 4- to 40-fold as compared to sterile controls; this matched the decrease in corrosion found with sterile medium in the absence of oxygen and with E . coli DH5 alpha grown anaerobically . In addition, the requirement for live respiring cells was demonstrated by the increase in the corrosion rate that was observed upon killing the P . fragi K biofilm in continuous cultures, and it was shown that fermentation products do not cause an increase in corrosion . Hence, pure-culture biofilms inhibit corrosion of SAE 1018 steel by depleting oxygen at the metal surface. J Periodontal Res, 1997 Jul, 32(5), 473 - 7 Effects of metronidazole on Porphyromonas gingivalis biofilms; Wright TL et al.; Subgingival bacteria exist within a biofilm consisting of cells and extracellular matrix which may afford organisms protection from both antibiotics and components of the host immune system . MIC values for planktonic Porphyromonas gingivalis treated with metronidazole were compared with those obtained for the same strain in biofilms associated with hydroxyapatite (HA) surfaces . The treated biofilms were examined for growth and studied by scanning electron microscopy . A broth assay resulted in an MIC of 0.125 microgram/ml for metronidazole against P . gingivalis, P . gingivalis biofilms exhibited growth after treatment with 20 micrograms/ml metronidazole, which was 160 times the MIC for planktonic organisms . The results of this study indicate that biofilm-associated P . gingivalis may be resistant to metronidazole at concentrations which are usually attained by systemic administration. Vet Res, 1997 Jul-Aug, 28(4), 353 - 63 Resistance of Escherichia coli growing as biofilms to disinfectants; Ntsama-Essomba C et al.; The bactericidal activity of various disinfectants (cationic or amphoteric surfactants, oxidizing agents, phenolic derivatives) was determined against Escherichia coli CIP 54127 obtained by culture on tryptic soy agar (in-suspension or on-germ-carrier test) or in the form of biofilms produced in a continuous culture system . The bacteria tested on germ-carriers or included in biofilms were more resistant than the same strain in suspension . The extent of the reduction in activity depended on the nature of the disinfectant . In the two cases, the greatest reduction was observed with benzalkonium chloride and hexadecyl trimethylammonium bromide, the agents with the lowest hydrophile-lipophile balance . The activity of the oxidizing agents (sodium hypochlorite, peracetic acid/H2O2) and alkyl trimethylammonium derivatives (C12 and C14) was somewhat reduced, while that of the phenolic derivatives (o-cresol, phenol) was either slightly attenuated or unaffected . The reduction in sensitivity was attributed to a reduced accessibility of the bacterial cells to the disinfectants, due to the fact that the former adhered to a support . Furthermore, the interfering action of the substances in contact with the bacteria (milk in the germ-carrier test and exopolymers in the biofilms) could play a role . The reduced sensitivity of the bacteria in the biofilms was not due to any alteration in the metabolic state of the bacteria (mostly in a quiescent state) since this resistance was lost after the mechanical resuspension of the cells before the contact with the disinfectants. Microbiology, 1997 Jul, 143 ( Pt 7), 2407 - 13 The effects of adherence to silicone surfaces on antibiotic susceptibility in Staphylococcus aureus; Williams I et al.; Sensitivity of Staphylococcus aureus to the antibiotics tetracycline, benzylpenicillin and vancomycin was found to decrease by 2-10 fold when cells were grown adherent to silicone catheter surfaces . Sensitivity to rifampicin and fusidic acid was not significantly altered in adherent cells . Susceptibility further decreased with increased adherence time prior to antibiotic challenge . The resistance observed was not genotypic, or due to the presence of a specialized subpopulation of bacteria, as it disappeared when the bacteria were removed from the catheter, subcultured and retested . Also, adherent bacteria were found to grow more slowly than bacteria growing planktonically . It is concluded that the decrease in antibiotic susceptibility of adherent bacteria is a function of the physiological status of the individual cells rather than a function of biofilm formation or slime production . The decrease in growth rate of the adherent bacteria is a result of the adherence process rather than a result of nutrient depletion . The decrease in growth rate is implicated, but is not the sole factor, in the decreased antibiotic susceptibility of adherent bacteria. Br J Urol, 1997 Jul, 80(1), 58 - 63 Which indwelling urethral catheters resist encrustation by Proteus mirabilis biofilms? Morris NS, Stickler DJ, Winters C. OBJECTIVE: To test the resistance of currently available types of indwelling urethral catheters to blockage by encrustation with mineralized Proteus mirabilis biofilms . MATERIALS AND METHODS: Encrustation was studied in a simple laboratory model of the catheterized bladder . Artificial urine was supplied to the bladder chamber at 0.5 mL/min . The bladder urine was inoculated with a clinical strain of P . mirabilis that had been isolated from an encrusted catheter . The models were operated until the catheters blocked and atomic absorption spectrometry was used to assess the amounts of calcium and magnesium deposited on the catheters . Scanning electron microscopy was also used to locate and assess the degree of encrustation . RESULTS: The mean times to blockage ranged from 21 h for the Bard hydrogel/silver-coated latex catheter to 56 h for the Eschmann Folatex S all-silicone catheter . The calcium and magnesium salts were mainly deposited on the 10 cm below the eye-holes of the catheters, complete blockage generally occurring in the 2 cm immediately below the eye-hole . CONCLUSION: None of the 18 types of catheter tested, including those coated with hydrogel or silver, were capable of resisting encrustation by P . mirabilis biofilm. Appl Environ Microbiol, 1997 Jul, 63(7), 2533 - 42 Optimization of L-(+)-lactic acid production by ring and disc plastic composite supports through repeated-batch biofilm fermentation; Ho KL et al.; Four customized bioreactors, three with plastic composite supports (PCS) and one with suspended cells (control), were operated as repeated-batch fermentors for 66 days at pH 5 and 37 degrees C . The working volume of each customized reactor was 600 ml, and each reactor's medium was changed every 2 to 5 days for 17 batches . The performance of PCS bioreactors in long-term biofilm repeated-batch fermentation was compared with that of suspended-cell bioreactors in this research . PCS could stimulate biofilm formation, supply nutrients to attached and free suspended cells, and reduce medium channelling for lactic acid production . Compared with conventional repeated-batch fermentation, PCS bioreactors shortened the lag time by threefold (control, 11 h; PCS, 3.5 h) and sixfold (control, 9 h; PCS, 1.5 h) at yeast extract concentrations of 0.4 and 0.8% (wt/vol), respectively . They also increased the lactic acid productivity of Lactobacillus casei subsp . rhamnosus (ATCC 11443) by 40 to 70% and shortened the total fermentation time by 28 to 61% at all yeast extract concentrations . The fastest productivity of the PCS bioreactors (4.26 g/liter/h) was at a starting glucose concentration of 10% (wt/vol), whereas that of the control (2.78 g/liter/h) was at 8% (wt/vol) . PCS biofilm lactic acid fermentation can drastically improve the fermentation rate with reduced complex-nutrient addition. Appl Environ Microbiol, 1997 Jul, 63(7), 2516 - 23 Ingredient selection for plastic composite supports for L-(+)-lactic acid biofilm fermentation by Lactobacillus casei subsp . rhamnosus; Ho KL et al.; Plastic composite supports containing 50% agricultural products (oat hulls, soybean hulls, yeast extract, soybean flour, dried bovine erythrocytes, bovine albumin, and/or mineral salts) and 50% (wt/wt) polypropylene were produced by high-temperature twin-screw extrusion . The research employed two half sets of a five-factorial fractional design (2(5 - 1)) to evaluate the effects of different agricultural components on the properties of the plastic composite supports and to select the best plastic composite support formulation for lactic acid fermentation . The biofilm population was affected by the contact angle and relative hydrophobicity of the supports (r = 0.79 to 0.82) . Lactic acid was produced by the suspended cells (r = 0.96) and the biofilm on the plastic composite support discs (r = 0.85) . Incorporation of yeast extract into plastic composite supports enhanced growth of free and attached cells in minimal medium (P < 0.0001) . The presence of soybean hulls, yeast extract, or mineral salts in plastic composite supports produced less hydrophobic supports (P < 0.0001) and enhanced cell attachment (P < 0.03) . Under all conditions, suspended-cell and polypropylene disc controls gave negligible lactic acid production and cell density . Plastic composite supports containing soybean hulls, yeast extract, soybean flour, bovine albumin, and mineral salts gave the highest biofilm population (2.3 x 10(9) CFU/g of support), cell density (absorbance of 1.8 at 620 nm), and lactic acid concentration (7.6 g/liter) in minimal medium. Arch Biochem Biophys, 1997 Jun 15, 342(2), 389 - 95 The major 20-kDa polysaccharide of Staphylococcus epidermidis extracellular slime and its antibodies as powerful agents for detecting antibodies in blood serum and differentiating among slime-positive and -negative S . epidermidis and other staphylococci species; Karamanos NK et al.; Staphylococcus epidermidis has been recognized as an important pathogen in immunocompromised hosts and patients with prosthetic or implanted medical devices . A highly adhesive extracellular material (slime or biofilm) produced by certain strains is associated with bacterial adherence to and growth on biomaterials contributing to pathogenesis of bacteremia . We have recently reported on the isolation and characterization of a sulfated 20-kDa acidic polysaccharide which constitutes slime's major component . Immunization of rabbits with crude slime and 20-kDa polysaccharide gave rise to readily reactive sera without manipulation of the 20-kDa polysaccharide structure . Immunological studies using purified polyclonal antibodies to 20-kDa polysaccharide by direct and competitive ELISA showed that they exhibit a high degree of reactivity and specificity with the homologous antigen . A significant proportion of the reactivity of antibodies to crude slime was also shown to be attributed to the 20-kDa polysaccharide . This polysaccharide is immunogenic in humans since blood sera derived from patients 10-15 days after confirmation of slime-producing S . epidermidis bacteremia gave approximately 16 times higher reactivity than that of healthy individuals . Antibodies to 20-kDa polysaccharide were able to recognize and react specifically with slime-positive S . epidermidis strains compared to slime-negative ones (2 to 5 times higher reactivity) . Moreover, these antibodies exhibited statistically significant (P < 0.05) differences in the degree of reactivity among S . epidermidis and other staphylococci species . These results open a new area in the diagnosis of S . epidermidis infection by direct analysis in blood sera, in differentiating among slime-positive and slime-negative strains as well as in distinguishing slime-producing S . epidermidis from other staphylococci species by simple laboratory tests. Endoscopy, 1997 Jun, 29(5), 372 - 9 Automatic washer disinfector for flexible endoscopes: a new evaluation process; Pineau L et al.; BACKGROUND AND STUDY AIMS: Many automatic washer disinfectors for flexible endoscopes have been marketed and offered as an alternative method of preventing infections, but they are frequently unsatisfactory . There is therefore clearly a need to test prototypes prior to marketing, following an evaluation process that is sufficiently reliable and rigorous to guarantee the efficacy of the decontamination processes . MATERIALS AND METHODS: The present study describes an experimental method based on the follow-up of the decontamination of a Tygon tube, the internal surface of which was contaminated by a bacterial biofilm . This method is proposed as a preliminary test for evaluating washer disinfectors . RESULTS: An analysis of the results obtained after technical modifications of the first prototype of the Fibro-Cleaner showed that complementary activities of each successive cycle phase allow a reduction in the number of adherent bacteria of more than 8 log per cm2 of support . With the three different biofilms tested (Escherichia coli, Pseudomonas aeruginosa mucoid and Staphylococcus aureus), no microorganisms were recovered from the support at the end of the decontamination process . CONCLUSIONS: The experimental protocol suggested here seems to be well suited for assessing washer disinfectors during the development phase of the prototype, as well as for comparative studies. J Ind Microbiol Biotechnol, 1997 Jun, 18(6), 396 - 401 Importance of biofilm formation for corrosion inhibition of SAE 1018 steel by axenic aerobic biofilms; Jayaraman A et al.; To investigate if corrosion inhibition by aerobic biofilms is a general phenomenon, carbon steel (SAE 1018) coupons were exposed to a complex liquid medium (Luria-Bertani) and seawater-mimicking medium (VNSS) containing fifteen different pure-culture bacterial suspensions representing seven genera . Compared to sterile controls, the mass loss in the presence of these bacteria (which are capable of developing a biofilm to various degrees) decreased by 2- to 15-fold . The extent of corrosion inhibition in LB medium depended on the nature of the biofilm: an increased proportion of live cells, observed with confocal scanning laser microscopy (CSLM) and image analysis, decreased corrosion . Corrosion inhibition in LB medium was greatest with Pseudomonas putida (good biofilm formation), while metal coupons exposed to Streptomyces lividans in LB medium (poor biofilm formation) corroded in a manner similar to the sterile controls . Pseudomonas mendocina KR1 reduced corrosion the most in VNSS . It appears that only a small layer of active, respiring cells is required to inhibit corrosion, and the corrosion inhibition observed is due to the attached biofilm. J Ind Microbiol Biotechnol, 1997 Jun, 18(6), 364 - 9 Fiber-reinforced polymeric composites are susceptible to microbial degradation; Gu JD et al.; A mixed culture of fungi, enriched from degraded polymeric materials, formed biofilms on coupons of fiber-reinforced polymeric composites (FRPCs) . They grew actively in aqueous extracts of the composites under ambient conditions . The data indicate that the fungi utilized the resins or fiber chemical sizing as carbon and energy sources . A progressive decline in impedance from above 10(7) Ohms to below 10(8) Ohms was detected in the inoculated FRPC panels by electrochemical impedance spectroscopy (EIS) after 179 days of incubation, but not on the sterile controls . The degradation proceeds through an initial ingress of water into the resins, followed by degradation of bonding between fiber surfaces and resins and finally separation of fibers from the resins . At the end of EIS study, the extent of disbonding in the inoculated composite was greater than the control observed by scanning electron microscopy . These results suggest that the composite materials are susceptible to microbial attack by providing nutrients for growth. Nippon Hinyokika Gakkai Zasshi, 1997 Jun, 88(6), 596 - 604 {A clinical study on combination therapy of antimicrobial agents for complicated urinary tract infection--with special reference to combination with clarithromycin}; Sano M et al.; PURPOSE: To confirm the clinical efficacy of the combined therapy to complicated urinary tract infection (UTI), we conducted a comparative clinical study of the combined therapy with ciprofloxacin (CPFX) and clarithromycin (CAM) acting an biofilm elimination or CPFX alone in patients with complicated UTI . PATIENTS AND METHODS: The study was carried out in patients with complicated UTI having WBCs with 5/hpf or more in urinary sediment and bacteriuria at least 10(4) CFU/ml . The combined therapy was CPFX and CAM, each 600 mg/day, for 14 days, and the single therapy group CPFX, 600 mg/day, for 14 days . On Day 7 and 14, the eradication rate and efficacy rate (according to the criteria of the Japanese UTI committee) were determined . In the patients with indwelling catheter, the surface of the catheter tip was observed under a scanning electron microscope (SEM) on Day 14 . RESULTS: In both cases with and without catheters, clinical efficacy was higher in the combined therapy group than in the single therapy group . In particular, the efficacy rates at 14 Day were significantly higher in the former group . Furthermore, we investigated the therapeutic effect in the below MIC breakpoint of CPFX in complicated UTI . The combined therapy group showed a higher clinical efficacy in both cases with and without indwelling catheter than the single therapy group, although there was not statistically significant . Biofilm on the surface of the catheter tip was eliminated in 75% of the combined therapy group . However, none of the biofilm was eliminated in the single therapy group . CONCLUSION: From the above results, we surmise that the combined use of CPFX and CAM will show some degree of efficacy in eliminating both the causative organism and its biofilm in the complicated UTI. Can J Microbiol, 1997 Jun, 43(6), 534 - 40 Recombinant plasmid mobilization between E . coli strains in seven sterile microcosms; Lebaron P et al.; Transfer by mobilization of a pBR derivative recombinant plasmid lacking transfer functions (oriT+, tra-, mob-) from one E . coli K12 strain to another was investigated in seven sterile microcosms corresponding to different environments . These microcosms were chosen as representative of environments that genetically engineered microorganisms (GEMOs) encounter after accidental release, namely attached biomass in aquatic environments (biofilm), soil, seawater, freshwater, wastewater, mouse gut, and mussel gut, GEMOs survived in the same way as the host strains in all microcosms . Recombinant DNA mobilization occurred in the mouse gut, in sterile soil, and in biofilm . The plasmid transfer rates principally reflected the environmental conditions encountered in each microcosm. J Antimicrob Chemother, 1997 Jun, 39(6), 817 - 20 Factors affecting development of rifampicin resistance in biofilm-producing Staphylococcus epidermidis; Svensson E et al.; Selection and regrowth of variants resistant to 0.016-32 mg/L of rifampicin, which were present at a frequency of 10(-7) in the initial inoculum, were seen when large inocula (> 10(5) cfu/mL) of Staphylococcus epidermidis ATCC 35984 were incubated with the drug . Conventional MIC determinations using approximately 10(5) cfu/mL did not detect the resistant variants . Larger inocula increased the MIC by > 8000-fold . Population analysis showed that rifampicin concentrations above the MIC (measured at an inoculum of approximately 10(5) cfu/mL) select highly resistant variants (MIC > 256 mg/L) when large inocula (> or = 10(5) cfu/mL) were incubated with rifampicin . The resistant variants were stable through ten passages . It was not possible to prevent regrowth of the resistant variants by increasing the rifampicin concentration further . At subinhibitory concentrations there was no development of rifampicin resistance. Mol Microbiol, 1997 Jun, 24(5), 1013 - 24 Evidence for autolysin-mediated primary attachment of Staphylococcus epidermidis to a polystyrene surface; Heilmann C et al.; Biofilm formation on a polymer surface which involves initial attachment and accumulation in multilayered cell clusters (intercellular adhesion) is proposed to be the major pathogenicity factor in Staphylococcus epidermidis foreign-body-associated infections . We have characterized two distinct classes of biofilm-negative Tn917 mutants in S . epidermidis affected in initial attachment (class A) or intercellular adhesion (class B) . mut1 (class A mutant) lacks five surface-associated proteins with molecular masses of 120, 60, 52, 45 and 38 kDa and could be complemented by transformation with a 16.4 kb wild-type DNA fragment . The complemented mutant was able to attach to a polystyrene surface, to form a biofilm, and produced all of the proteins missing from mut1 . Subcloning experiments revealed that the 60 kDa protein is sufficient for initial attachment . Immunofluorescence microscopy using an antiserum raised against the 60 kDa protein showed that this protein is located at the cell surface . DNA-sequence analysis of the complementing region revealed a single open reading frame which consists of 4005 nucleotides and encodes a deduced protein of 1335 amino acids with a predicted molecular mass of 148kDa . The amino acid sequence exhibits a high similarity (61% identical amino acids) to the atl gene product of Staphylococcus aureus, which represents the major autolysin; therefore the open reading frame was designated atlE . By analogy with the S . aureus autolysin, AtlE is composed of two bacteriolytically active domains, a 60 kDa amidase and a 52 kDa glucosaminidase domain, generated by proteolytic processing . The 120 kDa protein missing from mut1 presumably represents the unprocessed amidase and glucosaminidase domain after proteolytic cleavage of the signal- and propeptide . The 45 and 38kDa proteins are probably the degradation products of the 60 and 52 kDa proteins, respectively . Additionally, AtlE was found to exhibit vitronectin-binding activity, indicating that AtlE plays a role in binding of the cells not only to a naked polystyrene surface during early stages of adherence, but also to plasma protein-coated polymer surfaces during later stages of adherence . Our findings provide evidence for a new function of an autolysin (AtlE) in mediating the attachment of bacterial cells to a polymer surface, representing the prerequisite for biofilm formation. Curr Opin Biotechnol, 1997 Jun, 8(3), 328 - 34 Understanding and advancing wastewater treatment; Stams AJ et al.; In bioreactors used for the purification of wastewater, microorganisms are active in biofilms or aggregates . Insight into the factors that determine the structure and function of aggregated biomass is increasing steadily . Besides conventional techniques, modem molecular techniques are used increasingly to get a better understanding of the complex microbial communities in wastewater treatment systems . In recent years, the combined use of these techniques has led to a good insight into the population dynamics of different types of microbes in bioreactors. Antimicrob Agents Chemother, 1997 Jun, 41(6), 1352 - 8 Comparison of recalcitrance to ciprofloxacin and levofloxacin exhibited by Pseudomonas aeruginosa bofilms displaying rapid-transport characteristics; Vrany JD et al.; Attenuated total reflection Fourier transform infrared spectroscopy was used to measure transport of the fluoroquinolones (FQs) ciprofloxacin and levofloxacin into Pseudomonas aeruginosa biofilms . Biofilms were exposed to each FQ at dose levels of 100, 250, and 500 microg/ml for 30 min . A mathematical transport model was used to extract the diffusion coefficient, binding site density, and adsorption and desorption rates for each experiment . Recalcitrance of the biofilms toward each FQ was evaluated by comparison of efficacies with planktonic bacteria . By this criterion, biofilms were found to exhibit more recalcitrance toward levofloxacin than ciprofloxacin under the experimental conditions . These results cannot be explained by the more hindered transport of levofloxacin, implicating the domination of physiological factors. Biochim Biophys Acta, 1997 May 22, 1326(1), 37 - 46 Reactive liposomes encapsulating a glucose oxidase-peroxidase system with antibacterial activity; Hill KJ et al.; Liposomes were prepared from phospholipid mixtures of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylinositol (PI), encapsulating the enzymes glucose oxidase (GO) and GO in combination with horse radish peroxidase (HRP) by both extrusion (VET) and reverse-phase evaporation (REV) . The optimum level of PI in DPPC/PI liposomes for targeting to biofilms of the oral bacterium Streptococcus gordonii has been established . The liposomes were characterised in terms of the content and activity of the encapsulated enzymes . The antibacterial activity of these 'reactive' liposomes arising from hydrogen peroxide and oxyacids in the presence of the substrates glucose and iodide ions, after targeting to the biofilms, were measured both as a function of liposome-biofilm incubation time and incubation time with the substrates . Bacterial inhibition increases with both liposome-biofilm and substrate-biofilm incubation time and with the extent of enzyme encapsulation . The reactive liposomes also display antibacterial activity in the presence of saliva . The reactive liposomes have potential value in the context of oral hygiene. J Antimicrob Chemother, 1997 May, 39(5), 643 - 6 Influence of N-acetylcysteine on the formation of biofilm by Staphylococcus epidermidis; Perez-Giraldo C et al.; The influence of various concentrations (0.003-8 mg/mL) of N-acetylcysteine on the formation of biofilms by 15 strains of Staphylococcus epidermidis has been studied . A dose-related decrease in biofilm formation was observed, except with the lowest concentrations . The 'slime' index relative to the control was 63%, 55%, 46%, 34%, 26% and 26% in the presence of 0.25, 0.5, 1, 2, 4, and 8 mg/mL of N-acetylcysteine, respectively . These data are statistically significant . The inhibitory effect of 2 mg/mL of N-acetylcysteine on slime formation was also verified by electron microscopy. J Appl Microbiol, 1997 May, 82(5), 663 - 8 Synergism in biofilm formation between Salmonella enteritidis and a nitrogen-fixing strain of Klebsiella pneumoniae; Jones K et al.; A laboratory reactor, which simulates biofilm formation in water pipes, was used to study interactions in biofilm formation between a nitrogen-fixing strain of Klebsiella pneumoniae and Salmonella enteritidis . The level of attachment of Salm . enteritidis was higher in the binar biofilm than in the single species biofilm . In the initial colonization phase the binary biofilm contained a much higher proportion of metabolically active cells than in single species biofilms formed by either Salm . enteritidis or Kl . pneumoniae . When a pulse of Salm . enteritidis was passed over an already established biofilm of Kl . pneumoniae it rapidly became integrated into the biofilm, from where it was subsequently released into the water column, along with Kl . pneumoniae . Klebsiella pneumoniae fixed nitrogen in the presence of Salm . enteritidis in both types of biofilm. J Dairy Res, 1997 May, 64(2), 253 - 60 Binding of Staphylococcus aureus to milk fat globules increases resistance to penicillin-G; Ali-Vehmas T et al.; The susceptibility to penicillin-G of Staphylococcus aureus strains that cause mastitis was tested in milk and in Iso-sensitest broth (ISB): The minimal inhibitory concentrations (MIC) of beta-lactamase-positive strains in milk were 10-100-fold those in ISB, whereas the MIC of beta-lactamase-negative strains in milk were some 10-fold those in ISB; beta-lactamase production was induced by milk in beta-lactamase-positive strains . Much of the increase in resistance to penicillin-G caused by milk can be attributed to milk fat globules; the increase in resistance was related to the binding capacity of the bacteria to milk fat globules as well as to capsule formation by the bacteria . It appears that the binding of the staphylococci to the fat globules and bacterial capsule formation resulted in a biofilm type of growth . In this case, the staphylococci behaved differently from the planktonic type of growth in artificial broth medium in which antibiotic susceptibility testing is usually carried out. J Med Microbiol, 1997 May, 46(5), 425 - 9 Susceptibilities of Actinobacillus actinomycetemcomitans biofilms to oral antiseptics; Thrower Y et al.; The susceptibilities of Actinobacillus actinomycetemcomitans cultures, grown as 1- or 3-day-old biofilms or as planktonic suspensions, to concentrations of chlorhexidine digluconate, cetylpyridinium chloride or triclosan used in commercial mouthwashes were compared . Three-day biofilms were the most resistant form of the organism and chlorhexidine was the most active antiseptic . Comparison of solutions of the pure antibacterial agent with commercial products containing the same concentration of antiseptic showed little difference in in-vitro activities . The results emphasise that the testing of antimicrobial mouthwashes should be performed on bacteria grown as biofilms. J Appl Microbiol, 1997 Apr, 82(4), 519 - 26 Glutaraldehyde-resistant Mycobacterium chelonae from endoscope washer disinfectors; Griffiths PA et al.; Glutaraldehyde is used to disinfect flexible and other heat-sensitive endoscopes often with the aid of automated systems . Mycobacterium chelonae is being isolated with increasing frequency from these washer disinfectors and processed endoscopes . This has, on occasions, led to misdiagnosis and iatrogenic infections . Recent reports suggest that disinfecting machines, on a sessional or regular basis, with 2% glutaraldehyde may have selected and therefore encouraged the growth of strains of Myco . chelonae, possibly in biofilm, with decreasing susceptibility to glutaraldehyde . In view of this, the resistance of three strains of Myco . chelonae var . chelonae (the type strain NCTC 946 and two machine isolates) was tested against 2% glutaraldehyde and a wide range of alternative disinfectants . Disinfectants tested were a chlorine releasing agent, sodium dichloroisocyanurate at 1000 ppm and 10,000 ppm av Cl, 0.35% peracetic acid (NuCidex, Johnson & Johnson), 70% industrial methylated spirit (IMS), 1% peroxygen compound ('Virkon', Antec International) and 10% succine dialdehyde ('Gigasept', Sanofi Winthrop) . Suspension and carrier tests were carried out in the presence and absence of an organic load . Results showed the type strain, which had not been exposed to the selective pressure of disinfectant usage, to be very sensitive to most disinfectants with the exception of 1% Virkon . The washer disinfector isolates, on the other hand, were extremely resistant to 2% glutaraldehyde and showed greater resistance to 1% Virkon and 1000 ppm NaDCC . Purchasing machines in which the entire fluid pathways, including those for delivering rinse water, are disinfected with an appropriate agent during each cycle are preferred . If this is not possible then sessional cleaning and disinfection at the start of each day and regular maintenance should prevent biofilm formation and contamination with disinfectant-resistant strains of mycobacteria . In addition to machine disinfection, the use of sterile or bacteria-free (filtered < 0.45 microm) water is essential for bronchoscopes and all invasive endoscopes . If there is doubt that the effectiveness of the machine disinfection procedure or water quality, the channels and surfaces of endoscopes may be rinsed with 70% IMS after automated processing. Nutrition, 1997 Apr, 13(4 Suppl), 5S - 9S Microbial interactions with catheter material; Lewis WJ et al.; The use of central venous catheters to deliver parenteral nutrition therapy is often complicated by infection . The original source of these infections has been debated but it appears that organisms colonizing the skin or those contaminating the catheter hub are most often responsible . Before forming a biofilm, an organism must first successfully attach to a surface . To do this, microbes have evolved strategies that allow them to adhere to surfaces and evade forces that would favor their detachment . Once a biofilm is formed on a catheter, the organisms are relatively safe from a host immune response and antibiotics . In this review, what is known about these interactions is discussed. Kansenshogaku Zasshi, 1997 Apr, 71(4), 337 - 41 {Efficacy of erythromycin inhalation in chronic respiratory infection caused by Pseudomonas aeruginosa}; Yanagihara K et al.; The prognosis of chronic respiratory tract infection with Pseudomonas aeruginosad considered to be poor . However, low-dose and long-term 14 membered macrolide, such as erythromycin or clarithromycin, treatment has been reported as effective clinically in chronic lower respiratory tract disease . There was no report to investigate the effect of macrolide on chronic biofilm related Pseudomonas aeruginosa respiratory tract infection in vivo . In a newly established murine model of chronic Pseudomonas aeruginosa respiratory infection mimicking diffuse panbronchiolitis (DPB), we investigated the effect of erythromcin inhalation on viable bacteria in the lungs . Infection was produced by placement of a plastic tube in the bronchus with inoculating . Pseudomonas aeruginosa suspended in saline was also inoculated in bronchus after intubation of the tube . Viable bacteria were constantly isolated at 10(4) 10(6) cfu-specimen from the lungs for more than 30 days . Treatment with erythromycin inhalation for four days reduced the number of viable bacteria in the lungs with statistically significant . Our result indicated that our new model of chronic respiratory tract infection is simple and provides a useful tool to study the pathogenic process and treatment of such infection . Our results also suggest that the erythromycin inhalation is effective on chronic Pseudomons aeruginosa respiratory infection. Appl Microbiol Biotechnol, 1997 Apr, 47(4), 352 - 7 Immobilisation of whole bacterial cells for anaerobic biotransformations; Raihan S et al.; Anaerobically grown cells of Escherichia coli were immobilised within a range of entrapment matrices and packed into a column under standard conditions, and the ability of the immobilised cells to reduce nitrite (0.5 mM) was measured at a range of flow rates using sodium formate (20 mM) as the electron donor for nitrite reduction . A flow-rate/activity plot was constructed for each flow-through reactor and RA1/2 values (residence time corresponding to 50% nitrite removal) calculated for each reactor type . Cells immobilised in flat and hollow-fibre membranes were the most effective (RA1/2 = 0.35 h and 0.47 h respectively), with cells entrapped by dialysis membrane (1.53 h), alginate beads (1.93 h), Hypol foam (2.31 h) and polyacrylamide gel (50% nitrite not removed at maximum residence time tested: 4.9 h) performing progressively less effectively . Cells grown as a biofilm on a range of support materials were also tested in comparable packed-bed reactors . Cell loss from these supports was extensive and contributed to poor performance of the reactors despite high initial biomass loadings (RA1/2 values using raschig rings, coke and activated-carbon supports: 1.6 h, 2.3 h and 1.0 h respectively) . Biofilms grown on Pharmacia microcarrier supports and used in packed and also fluidised beds were more stable and the performance of these reactors was superior to that of biofilm reactors using other supports, and comparable to that of the membrane reactors (RA1/2 values for Cytoline 2, Cytopore 2 and Cytodex 3: 0.76 h, 0.56 h, 0.68 h respectively). Pharm Res, 1997 Apr, 14(4), 503 - 7 The effect of intestinal bacteria adherence on drug diffusion through solid films under stationary conditions; Rubinstein A et al.; PURPOSE: To study the in vitro and in vivo the role of surface bacterial adhesion on the diffusion of model drugs at stationary conditions . METHODS: Salicylic acid (SA) diffusion through ethyl cellulose (EC) films was measured in vitro in side-by-side diffusion cells with and without E . coli of intestinal origin . Insulin (I) release from paper strips coated or uncoated with pectin films, with or without antibiotic treatment, was measured in vivo in conscious rats after cecal implantation by comparing blood glucose levels at Tmax of the pharmacodynamic effect . RESULTS: During five hours of diffusion studies which were performed immediately following incubation of EC films with bacteria, the diffusion rate of SA throughout the films was 2.72-fold lower in the presence of bacteria compared with the diffusion rate in the control studies conducted without bacteria . The mean blood glucose levels dropped in the rat to 40.6 +/- 21.6% of glucose basal levels within 2.4 +/- 1.4 h when uncoated I solid carriers were used . Glucose levels did not change for pectin-coated dosage forms . After antibiotic treatment which prevented the formation of bacterial biofilm on the surface of the I solid dosage forms, blood glucose levels dropped to 22.0 +/- 4.7% and 50.9 +/- 20.5% of glucose basal levels within 7.4 +/- 2.6 h and 1.8 +/- 0.9 h for pectin uncoated or coated dosage forms, respectively . Maximum bacterial adherence occurred at stationary conditions (RPM = 0), while at maximum agitation (200 RPM), almost no adherence occurred . CONCLUSIONS: (a) Bacterial adherence shows down the diffusion rate of SA through EC films; (b) Under stationary conditions bacterial adherence may also interfere with drug release from biodegradable (pectin) films; (c) Successful functioning of biodegradable colon-specific delivery systems depends on agitation and surface friction in the lumen of the colon. Int J Food Microbiol, 1997 Mar 3, 34(3), 197 - 207 Infection and removal of L-forms of Listeria monocytogenes with bred bacteriophage; Hibma AM et al.; Phage breeding was employed to produce a bacteriophage (Listeria monocytogenes phage ATCC 23074-B1) which was specific for L-forms of L . monocytogenes . The bred phage was compared to its unbred parent for lytic activity and specificity . It was also tested for its ability to prevent L-form biofilm formation on stainless steel and compared with an organic acid (lactic) at L-form biofilm inactivation on stainless steel . The bred phage lysed only L-forms of L . monocytogenes in broth culture and only plaqued on L-form lawns . Likewise, the unbred phage performed similarly with classical cell-walled culture and lawns . The bred phage successfully inhibited L-form biofilm formation on stainless steel and was as successful as lactic acid (130 ppm) at inactivating pre-formed L-form biofilms . Both reduced viable cell numbers by 3-long cycles over a 6 h period . It appears that phage breeding technology may be an attractive alternative to chemical sanitizers which lack specificity and can be toxic. Chemotherapy, 1997 Mar-Apr, 43(2), 137 - 41 Effect of the growth rate of Pseudomonas aeruginosa biofilms on the susceptibility to antimicrobial agents; Shigeta M et al.; The growth rate of biofilm cells of a leucine-requiring mutant Pseudomonas aeruginosa HU1 was regulated by the leucine concentration in the chemically defined medium, and the effect of the growth rate of biofilm cells on the antimicrobial activities of the antimicrobial agents piperacillin (PIPC), imipenem (IPM) and ofloxacin (OFLX) were evaluated . PIPC showed little effect on the biofilm bacteria regardless of the leucine concentration in the medium . IPM showed weak bactericidal activity to biofilm cells; activity was greater in younger biofilm cells growing in high concentrations of leucine . On the other hand, OFLX revealed strong bactericidal activity to biofilm bacteria regardless of the growth rate . Our data suggest that the bactericidal action of antimicrobial agents to biofilm bacteria is different from that to planktonic bacteria . The bioassay using mutants with regulated growth is useful for the evaluation of the efficacy of antimicrobial agents against biofilm bacteria. Lett Appl Microbiol, 1997 Mar, 24(3), 177 - 9 Elimination of adhering bacteria from surfaces by pulsed laser beams; Sadoudi AK et al.; As an alternative to the use of chemicals for cleaning and disinfecting surfaces of equipment in food industry, the efficacy of pulsed laser beams for removal and killing of adherent bacteria from stainless steel surfaces was assessed . Escherichia coli biofilms were produced under dynamic conditions in diluted nutritive medium incubated at 37 degrees C for 24 h . Influence of energy density and number of shots were tested at three wavelengths (1064, 532 and 355 nm) . With one 20 ns pulse, results range from 3.5 decimal reductions of the microbial load with < or = 50 MW cm-2 without visible alteration of the surface, to more than 6 decimal reductions with < or = 600 MW cm-2 . The measured effect was largely attributed to removal of the micro-organisms and transfer to the surrounding air . The treatment could therefore be improved with respect to the numbers remaining associated with the surface by venting. Infect Immun, 1997 Mar, 65(3), 890 - 6 Detection of the intercellular adhesion gene cluster (ica) and phase variation in Staphylococcus epidermidis blood culture strains and mucosal isolates; Ziebuhr W et al.; Staphylococcus epidermidis is a common cause of catheter-associated infections and septicemia in immunocompromised patients . To answer the question whether S . epidermidis skin isolates differ from isolates causing septicemic diseases, 51 strains obtained from blood cultures, 1 strain from shunt-associated meningitis, and 36 saprophytic isolates were characterized . The study demonstrates that most of the blood culture strains formed a multilayered biofilm on plastic material, whereas skin and mucosal isolates did not . Moreover, biofilm-producing strains were found to generate large bacterial autoaggregates in liquid culture . Autoaggregation and biofilm formation on polymer surfaces was associated with the presence of a DNA sequence encoding an intercellular adhesion gene cluster (ica) that mediates the production of a polysaccharide intercellular adhesin . The presence of the intercellular adhesion genes in blood culture isolates was also found to be correlated with the exhibition of black colonies on Congo red agar, whereas the adhesin-negative strains formed red colonies . Upon subcultivation on Congo red agar, the black colony forms of the blood culture strains exhibited red colony variants which were biofilm and autoaggregation negative and occurred at a frequency of 10(-5) . The DNA analysis of these S . epidermidis variants by pulsed-field gel electrophoresis and Southern hybridization with an ica-specific gene probe revealed no detectable difference between the black and red colony types . Moreover, after repeated passage, the phenotype of the parent strain could be restored . Therefore, these colony forms were regarded as phase variants . This phenotypic change was observed exclusively in adhesin-positive clinical isolates and not in adhesin-negative saprophytic strains of S . epidermidis. Community Dent Oral Epidemiol, 1997 Feb, 25(1), 126 - 34 Promoting changes in clinical practice . Treatment time and outcome studies in a Danish public child dental health clinic; Thylstrup A et al.; This paper examines the characteristics of the process of innovation as applied to provision of dental health to children . The data are from a demonstration project conducted in a Danish public child dental health clinic to evaluate the appropriateness and effectiveness of an individualized and alternative, mainly non-operative caries treatment strategy that was implemented in 1987 . The aim of the strategy was to avoid operative intervention and sealants, and was based on three principles: caries is a localized disease; intensive training in home-based treatment, and individualized risk assessments and controls in conjunction with professional plaque removal . The major influence on the innovation process appeared to be personal education of the personnel, active participation in research, and feedback from clinical observations . In 1992 an additional feedback measure was introduced addressing the question: how much time does the individual child spend on treatment during one year? Mean total treatment time varied from 12 min 1- to 4-yr-olds to 44-58 min for 7- to 17-yr-olds . About 60% of the total treatment time was used on non-operative caries treatment (diagnosis, risk assessment, plaque removal, toothbrushing training) and about 25% on operative caries treatment for 3- to 17-yr-olds . The 1-2-yr-olds required only non-operative treatment . The new treatment strategy reduced operative procedures by 60% . The paper introduces an easily applicable measure of treatment outcome in terms of teeth that have not been restored or sealed as a result of regular professional treatment or care . The main conclusion drawn is that the dominant moving forces in the innovation process were professional responsibility and self-adjustment by a constant learning process involving clinical feedback measures in conjunction with modern understanding of caries as a localized disease caused by local evolution of microbial cariogenic biofilms. Community Dent Oral Epidemiol, 1997 Feb, 25(1), 76 - 81 Does assessment of microbial composition of plaque/saliva allow for diagnosis of disease activity of individuals? Bowden GH. Microbiological tests are limited in their applicability in the assessment of caries activity and in caries prediction . They can be effective in group of persons with high or low caries experience . The reasons for the limitation of microbiological tests rests with unique characteristics of the microflora and local environments of the oral cavity, which will modify the cariogenicity of plaque in an individual . Thus, high numbers of S . mutans may be associated with the development of a lesion at a site, while a second susceptible site with high levels of this organism in the same subject will remain caries free . This paper identifies some aspects of oral bacteria which can contribute to the unique nature of the microflora associated with plaque in an individual . Firstly, the range of bacteria potentially involved in caries has widened and now includes, for example, 'low pH' non-mutans streptococci . The presence of such organisms in plaque in an individual may influence early enamel demineralization . Most significantly, Streptococcus mutans, Streptococcus mitis and Actinomyces naeslundii have been shown to be comprise many distinct clones, with different distribution among subjects . Little is known of the impact of clonal diversity on caries activity but in some bacterial diseases particular clones are associated with virulence . Therefore, possession of a particular clone or clones by an individual could be related to caries activity . Also, the extent of clonal diversity may reflect the nature of the oral environment . Recent studies suggest that cells are released from biofilms, during adherence and growth, i.e . the early phases of development . Thus, determination of the numbers of a given species in non-stimulated saliva may indicate whether it is actively growing in plaque . Microbiological tests on the oral flora should perhaps be used to monitor the status of the oral cavity, after establishing a norm for the individual patient . Research on species and clonal diversity of oral bacteria among human populations; diversity and its role in the caries process; and the liberation of biofilm cells could provide data to allow better appreciation and evaluation of the results of microbiological testing. Infect Immun, 1997 Feb, 65(2), 519 - 24 A 140-kilodalton extracellular protein is essential for the accumulation of Staphylococcus epidermidis strains on surfaces; Hussain M et al.; Two distinct pathogenic mechanisms, adhesion to polymer surfaces and subsequent accumulation of sessile bacterial cells, are considered important pathogenic steps in foreign body infections caused by Staphylococcus epidermidis . By using mitomycin mutagenesis, we have recently generated a mutant, strain M7, from S . epidermidis RP62A which is unaffected in adhesion but deficient in accumulation on glass or polystyrene surfaces and lacks a 115-kDa extracellular protein (designated the 140-kDa antigen; F . Schumacher-Perdreau, C . Heilmann, G . Peters, F . Gotz, and G . Pulverer, FEMS Microbiol . Lett . 117:71-78, 1994) . To evaluate the role of this protein in accumulation, we harvested extracellular proteins from S . epidermidis RP62A grown on dialysis membranes placed over chemically defined medium, purified the protein by using ion-exchange chromatography, determined its N-terminal amino acid sequence, and raised antiserum in rabbits . The antibody recognized only a single band in a Western immunoblot of the crude extracellular extract . With the microtiter biofilm test, antiserum at a dilution of < or =1:1,000 blocked accumulation of RP62A up to 98% whereas preimmune serum did not . The 140-kDa antigen was found only in extracellular products from bacteria grown under sessile conditions . Of 58 coagulase-negative clinical isolates, 32 strains were 140-kDa antigen positive and produced significantly larger amounts of biofilm than the 26 strains that were 140-kDa antigen negative . The 140-kDa protein appears to be biochemically and functionally unrelated to any previously described factors associated with biofilm formation . Thus, the 140-kDa antigen, referred to as accumulation-associated protein, may be a factor essential in S . epidermidis accumulation and, due to its immunogenicity, may allow the development of novel immunotherapeutic strategies for prevention of foreign body infection. Eur Arch Otorhinolaryngol, 1997, 254(6), 261 - 3 A new method for in vivo evaluation of biofilms on surface-modified silicone rubber voice prostheses; Everaert EP et al.; A new method is presented that permits a rapid and accurate in vivo evaluation of biofilm formation on surface-modified silicone rubber voice prostheses . The method is based on partial modification of a Groningen button voice prosthesis by exposing half of the prosthesis to an argon plasma . This results in one side of the prosthesis becoming hydrophilic while leaving the unmodified side hydrophobic as a control . Modified prostheses were placed in patients for an evaluation period of approximately 4 weeks . Despite making the silicone rubber surface hydrophilic, biofilm formation was stimulated when compared to unmodified, hydrophobic silicone rubber . Findings show that biofilm formation on voice prostheses is influenced by hydrophobicity of a silicone rubber surface . The method of partial surface modification used was seen to be suitable for demonstrating such influences regardless of nutrition and other variations in the patient's lifestyle . Microbiological analysis of the biofilms on both sides of the prosthesis valve did not show any changes in microbial composition, with Candida albicans, streptococci and staphylococci being the most commonly isolated strains. Ann Pharm Fr, 1997, 55(2), 49 - 54 {Bacterial biofilms and resistance to disinfectants}; Vidal DR et al.; When bacteria grow in close association with solid surface, they constitute a microbial community tight included in the exopolymer glycocalyx . Many laboratory studies have shown that these bacteria are 10 to 100 folds more resistant to disinfectants than the bacteria of the same strain in suspension . Several factors are responsible for this resistance: the glycocalyx which limits the diffusion and reacts with the disinfectant, the more or less dense repartition of the bacteria inside the biofilm, their physiologic state with reduced metabolism, and the surface on which is the biofilm . The activity assessment of disinfectant agents is achieved with standardized methods . They must take into account not only the conditions in which the disinfectants are employed, but also the micro-organism state . Experimental results showing the resistance of biofilm bacteria must lead to elaborate methods allowing the assessment of bactericide activity of disinfectants against biofilm bacteria. Caries Res, 1997, 31(3), 194 - 200 A method for the quantitative site-specific study of the biochemistry within dental plaque biofilms formed in vivo; Robinson C et al.; The study of plaque biofilms in the oral cavity is difficult as plaque removal inevitably disrupts biofilm integrity precluding kinetic studies involving the penetration of components and metabolism of substrates in situ . A method is described here in which plaque is formed in vivo under normal (or experimental) conditions using a collection device which can be removed from the mouth after a specified time without physical disturbance to the plaque biofilm, permitting site-specific analysis or exposure of the undisturbed plaque to experimental conditions in vitro . Microbiological analysis revealed plaque flora which was similar to that reported from many natural sources . Analytical data can be related to plaque volume rather than weight . Using this device, plaque fluoride concentrations have been shown to vary with plaque depth and in vitro short-term exposure to radiolabelled components may be carried out, permitting important conclusions to be drawn regarding the site-specific composition and dynamics of dental plaque. Int Orthop, 1997, 21(1), 46 - 51 Adherence of Staphylococcus aureus slime-producing strain variants to biomaterials used in orthopaedic surgery; Gracia E et al.; The adherence of Staphylococcus aureus to biomaterials used in orthopaedic surgery (polymethylmethacrylate, fresh bone, steel and titanium alloys) and to glass was studied in vitro at 1, 2, 6, 24 and 48 h of incubation . Nonslime-producing strains (72, 80 and 510) and slime-producing variants of these strains were used . An automated and fast method of ATP-bioluminiscence was applied to determine bacterial viability . The lowest adherence corresponded to polymethylmethacrylate and bone, and the highest to metals . Significant adherence was detected in all cases after 6 h and was strain dependent, being lowest for strain 72 . In most cases, adherence of nonslime-producing variants was not significant compared with controls, and slime-producing were more adherent than nonslime-producing variants . These differences were maximal at 6 h or 48 h, depending on the strain and the material . The findings suggest that the appearance of slime-producing cells within a given nonslime-producing bacterial population may jeopardise postoperative immune systems and antibiotic efficacy as a consequence of biofilm formation on implants and prostheses. Ann Biomed Eng, 1997 Jan-Feb, 25(1), 69 - 76 The effect of ultrasonic frequency upon enhanced killing of P . aeruginosa biofilms; Qian Z et al.; It is widely recognized that the bacteria sequestered in a biofilm on a medical implant are much more resistant to antibiotics than their planktonic counterparts . Recent studies have shown that application of antibiotic along with low power ultrasound significantly increases the killing of planktonic bacteria by the antibiotic . Herein is reported a similar application of antibiotic and ultrasound to sessile bacteria in biofilms of Pseudomonas aeruginosa on a polyethylene substrate . Biofilm viability was measured after exposure to 12 micrograms/ml gentamicin sulfate and 10 mW/cm2 ultrasound at frequencies of 70 kHz, 500 kHz, 2.25 MHz, and 10 MHz . The results indicate that a significantly greater fraction of the bacteria was killed by gentamicin when they were subjected to ultrasound . However, ultrasound by itself did not have any deleterious effect on the biofilm viability . In addition, lower-frequency insonation is significantly more effective than higher frequency in reducing bacterial viability within the biofilm . The possible mechanisms of synergistic action are discussed. ASAIO J, 1997 Jan-Feb, 43(1), 8 - 12 In vitro and in vivo effects of rifampin on Staphylococcus epidermidis graft infections; Garrison JR Jr et al.; Rifampin, bound in high concentrations to prosthetic grafts, has been proposed for the treatment of vascular graft infections . The optimum antibiotic concentration and duration of treatment for infected grafts is not known . This study compared the in vitro and in vivo efficacy of varying concentrations of rifampin against three different strains of slime producing Staphylococcus epidermidis (RP62A, KC2, and KB1) bound to the knitted Dacron at high and low concentrations at 10(4) and 10(7) CFU/cm2 of prosthetic . Time kill experiments were performed at 4, 18, and 42 hr, in which each Dacron bound bacterial strain was exposed in vitro to 4X, 64X, 100X, and 1,000X minimum inhibitory concentration (MIC) of rifampin . In vitro, the Dacron bound laboratory strain RP62A was implanted subcutaneously in the backs of male Swiss-Webster mice and exposed to 4X, 100X, and 1,000X the MIC of rifampin for similar time periods . In addition, systemic vancomycin (10 mg/kg) was assessed for synergy and prevention of rifampin resistance . In vitro, all concentrations of rifampin showed near total killing (< 1 log) of all bacterial strains at low initial concentrations (10(4) CFU/cm2) but not high (10(7) CFU/cm2) to 42 hr . Importantly, resistance was shown to develop in all three strains of S . epidermidis with high initial bacterial biofilm concentrations . In vivo, rifampin concentrations between 4X MIC and 100X MIC achieved a balance between optimal killing and prevention of resistance . Systemic vancomycin slightly improved bacterial clearance but did not alter the development of rifampin resistance at high local concentrations . Caution is advised with the use of antibiotic bonded grafts because resistance may develop even with the addition of systemic antibiotics. Ophthalmologica, 1997, 211 Suppl 1, 9 - 14 A new perspective in ocular infection and the role of antibiotics; Miyanaga Y; A new concept of ocular infectious diseases includes two modes of pathogenesis, one being an acute inflammation caused by the attachment of free-floating bacteria, and another being intractable biofilm-related ocular infections . 15-20% of Staphylococcus epidermidis strains isolated from human conjunctiva exhibit slime formation and can be pathogens causing inflammation . Topical application, in the form of, for example, eye drops, of a combination of two antimicrobial agents is usually applied to treat such infections . Any antimicrobial agent having a post-antibiotic effect is generally administered in a twice-a-day regimen. Appl Microbiol Biotechnol, 1997 Jan, 47(1), 18 - 22 Electrochemical disinfection of drinking water using an activated-carbon-fiber reactor capable of monitoring its microbial fouling; Okochi M et al.; An electrochemical reactor employing activated carbon fibers (ACF) was constructed for the disinfection of bacteria in drinking water . The application of an alternating potential of 1.0 V and -0.8 V versus a saturated calomel electrode, for disinfecting and desorbing bacteria, enabled reactor operation for 840 h . Drinking water was passed through the reactor in stop/flow mode: 300 ml/min flow for 12 h and no flow for 12 h, alternately . The bacterial cell density in treated water was always been less than 20 cells/ml . It was also found that the formation of biofilm on the ACF reactor caused an increase in current, enabling the self-detection of microbial fouling. Biomaterials, 1997 Jan, 18(1), 87 - 91 Adhesion of Lactobacillus species in urine and phosphate buffer to silicone rubber and glass under flow; Millsap KW et al.; Coating uroepithelial cells or catheter materials with lactobacilli has been shown to retard the development of a uropathogenic biofilm, with biosurfactant production and strong adhesion being two prerequisite properties of the Lactobacillus strains to be employed . In this paper, adhesion of six selected Lactobacillus strains to silicone rubber and glass in urine and in a phosphate buffer was studied using a parallel plate flow chamber . In addition, adhesive cell surface properties of the lactobacilli, i.e . the pH dependences of their zeta potentials and their hydrophobicities by water contact angles, were determined . L . acidophilus ATCC 4356 and L . fermentum B54 were the only strains showing significant adhesion to both hydrophobic silicone rubber and hydrophilic glass, possibly by virtue of their high cell surface hydrophobicities (water contact angles of 68 and 75 degrees, respectively) and small zeta potentials (-10.0 and -8.1 mV in buffer, respectively) . Both hydrophobic Lactobacillus strains adhered less well in urine than in buffer . The remaining Lactobacillus strains studied were hydrophilic, with water contact angles between 25 and 36 degrees, and had highly negative zeta potentials, reaching -37.7 mV in buffer . Adhesion of these highly negatively charged, hydrophilic strains in buffer was essentially absent, while for some of these strains minor adhesion in urine was observed . This study demonstrates that the adhesion of lactobacilli to substrata differs with strain hydrophobicity and charge, and that urinary components can affect the ability of hydrophilic Lactobacillus strains to adhere to substrata. Biomaterials, 1997 Jan, 18(1), 53 - 7 Corrosion of the intra-oral magnets by multi-species biofilms in the presence and absence of sucrose; Wilson M et al.; The purpose of this study was to determine the corrosive effects of multi-species biofilms on intra-oral magnets in the presence and absence of sucrose . Using pooled human saliva as an inoculum, biofilms were grown on the surfaces of 90 neodymium-iron-boron (Nd2Fe14B) magnets in a constant depth film fermentor under aerobic conditions at 37 degrees C . The fluid phase was a mucin-containing artificial saliva (delivered at a rate of 0.72/litres day-1), and, after 15 days, 100 ml of 10% (w/v) sucrose was added (as three pulses of 33.3 ml) each day for a further 15 days . Six magnets with attached biofilms were removed periodically . On each sampling occasion the numbers of aerobes, anaerobes, streptococci, veillonellae and actinomyces in each biofilm, the pH of the fermentor effluent and the dry mass of the magnets were determined . Addition of sucrose to the fermentor resulted in a fall in pH (from a mean of 6.94 to a mean of 4.96), an increase in the proportion of streptococci and a decrease in the proportion of veillonellae comprising the biofilms . The decrease in mass of the magnets was 28-fold greater in the presence of sucrose than in its absence . The results of this study have shown that the presence of sucrose affects the microbial composition of multi-species biofilms growing on Nd2Fe14B magnets and results in a marked increase in corrosion of the magnets. Appl Environ Microbiol, 1997 Jan, 63(1), 270 - 6 Succession and convergence of biofilm communities in fixed-film reactors treating aromatic hydrocarbons in groundwater; Massol-Deya A et al.; Community composition, succession, and performance were compared in three fluidized bed reactors (FBR) operated to test preemptive colonization and the influence of toluene compared with a mixture of benzene, toluene, and p-xylene (BTX) as feeds . One reactor was inoculated with toluene-degrading strains Pseudomonas putida PaW1, Burkholderia cepacia G4, and B . pickettii PKO1 . PaW1 outcompeted the other two strains . When groundwater strains were allowed to challenge the steady-state biofilm developed by inoculated strains, they readily displaced the inoculated strains and further reduced the toluene effluent concentration from 0.140 to 0.063 mg/liter for 98% removal . Amplified ribosomal DNA restriction analysis (ARDRA) of reactor community DNA showed a succession of populations to a pattern that was stable for at least 4 months of operation . Parallel reactors fed toluene and BTX but inoculated directly from groundwater had the same treatment performance and the same ARDRA profiles as each other and as the seeded reactor once the groundwater community took over . Convergence and stability of populations were confirmed by genotype analysis of 120 isolates taken from all reactors and at several times . Ninety percent of the isolates were of 4 of the 12 genotypes found, and their ARDRA patterns accounted for most of the community ARDRA patterns . Estimates of the maximum specific growth rates (mu max), half-saturation constants (K(m)), and maximum substrate utilization rates (Vmax) of the 12 genotypes isolated revealed a rather high diversity of toluene use kinetics even though the toluene in the feed was constant . The climax populations, however, generally showed kinetic parameters indicative of greater competitiveness than the inocula . rRNA sequence analysis of three codominant strains showed them to be members of the alpha, beta, and gamma subdivisions of the Proteobacteria . Two were similar to Comamonas and Pseudomonas putida, but the member of the alpha group was somewhat distant from any organism in the rRNA database . The convergence of communities to the same composition from three different starting conditions and their constancy over several months suggests that a rather stable community was selected. J Gastroenterol, 1996 Dec, 31(6), 836 - 43 Bacterial adhesion on hydrophilic heparinized catheters, with compared with adhesion on silicone catheters, in patients with malignant obstructive jaundice; Homma H et al.; To study the inhibitory effects on bacterial adhesion of a newly devised, hydrophilic heparinized catheter to be used in patients with malignant obstructive jaundice, a randomized controlled study of indwelling endoprostheses was performed, using implantable port-connected heparinized catheters (n = 25) and silicone catheters (n = 21) . Catheters withdrawn from patients were cultured for bacteria and examined by electron microscopy for the presence of adherent organisms . In vitro examination of the two type of catheters exposed to suspensions of Eschericia coli and Staphylococcus aureus was performed using electron microscopy and a luminometer . The formation of a biofilm coated with glycocalyces was found in silicone catheters, but not in the heparinized catheters . In vitro experiments demonstrated little bacterial adhesion to the heparinized surface, but significant formation of biofilm on the silicone surface . Anionically charged heparinized catheters have inhibitory effects on bacterial adhesion, and the surface charge of the catheter may be a factor in inhibiting this adhesion. J Antimicrob Chemother, 1996 Dec, 38(6), 987 - 1000 The efficacy of antibiotics enhanced by electrical currents against Pseudomonas aeruginosa biofilms; Jass J et al.; Low electrical currents are reported to enhance the activity of tobramycin and biocides against biofilm bacteria . We report that the activity of those antibiotics to which the bacterium is susceptible in its planktonic state may be enhanced by a low electrical current against the more resistant biofilm cells . Pseudomonas aeruginosa biofilms were formed on a dialysis membrane suspended between two parallel electrode plates in an electrical colonisation cell . Ciprofloxacin, polymyxin B and piperacillin were tested on biofilms at ten times their MIC for 12 h in the presence of 0 (control) and 9 mA/cm2 current density . At these concentrations the antibiotics alone reduced the biofilm population, but in the presence of an electrical current the population was further reduced by ciprofloxacin and polymyxin B though not by piperacillin . Exposure of the planktonic bacteria to the same concentrations of antibiotics demonstrated that ciprofloxacin and polymyxin B reduced the population to below 1% after 12 h and below 0.1% after 24 h, while piperacillin was bacteriostatic . The results suggest that the electrical current can enhance the activity against biofilms of only those antibiotics that are effective against planktonic cells. Int J Food Microbiol, 1996 Dec, 33(2-3), 157 - 67 In vivo bioluminescence to detect the attachment of L-forms of Listeria monocytogenes to food and clinical contact surfaces; Hibma AM et al.; A bioluminescent phenotype of Listeria monocytogenes was employed to study the adhesion and biofilm formation of both classical and L-forms to relevant food and clinical contact surfaces . Attachment of both parental (cell-walled) and L-forms to intravenous tubing and stainless steel was compared using viable counts and bioluminescence . Both cell types attached themselves to intravenous tubing and stainless steel . Parental cell numbers attached to intravenous tubing were 1 log higher than L-form numbers, and on stainless steel, attached L-form numbers were 1 log higher . Bioluminescence measurements yielded a pattern similar to viable count measurements . There was a clear relationship between light output of attached bacteria and their viability and, thus, a bioluminescent phenotype provides a rapid monitor of both microbial viability and biofilm formation by L-forms. J Colloid Interface Sci, 1996 Nov 10, 183(2), 498 - 505 The Use of Microelectrodes to Study the Precipitation of Calcite upon Algal Biofilms Hartley AM, House WA, Leadbeater BSC, Callow ME. Calcium and pH ion-selective microelectrodes are used for the first time to measure chemical activity profiles above laboratory-grown algal biofilms (green alga, Chlorococcum sp) . The results are used to calculate the solution composition changes above an actively photosynthesizing biofilm . These changes include the total calcium concentration, degree of supersaturation of the solution with respect to calcite, and the partial pressure of carbon dioxide . Measurements are made in a flow-cell, which was designed to hold the templates on which the biofilms are grown . Measurements show pronounced gradients of pH and calcium concentration, within a distance of approximately 500 &mu;m above the biofilm . The high degree of supersaturation caused by the low concentrations of carbon dioxide near the biofilm surface leads to the precipitation of calcite on the biofilm . SEM micrographs illustrate the close association of calcite crysta