Infect Immun, 1995 Jan, 63(1), 229 - 37 Avirulence of rough mutants of Shigella flexneri: requirement of O antigen for correct unipolar localization of IcsA in the bacterial outer membrane; Sandlin RC et al.; Mutations in the lipopolysaccharide (LPS) of Shigella spp . result in attenuation of the bacteria in both in vitro and in vivo models of virulence, although the precise block in pathogenesis is not known . We isolated defined mutations in two genes, galU and rfe, which directly affect synthesis of the LPS of S . flexneri 2a, in order to determine more precisely the step in virulence at which LPS mutants are blocked . The galU and rfe mutants invaded HeLa cells but failed to generate the membrane protrusions (fireworks) characteristic of intracellular motility displayed by wild-type shigellae . Furthermore, the galU mutant was unable to form plaques on a confluent monolayer of eucaryotic cells and the rfe mutant generated only tiny plaques . These observations indicated that the mutants were blocked in their ability to spread from cell to cell . Western immunoblot analysis of expression of IcsA, the protein essential for intracellular motility and intercellular spread, demonstrated that both mutants synthesized IcsA, although they secreted less of the protein to the extracellular medium than did the wild-type parent . More strikingly, the LPS mutants showed aberrant surface localization of IcsA . Unlike the unipolar localization of IcsA seen in the wild-type parent, the galU mutant expressed the protein in a circumferential fashion . The rfe mutant had an intermediate phenotype in that it displayed some localization of IcsA at one pole while also showing diffuse localization around the bacterium . Given the known structures of the LPS of wild-type S . flexneri 2a, the rfe mutant, and the galU mutant, we hypothesize that the core and O-antigen components of LPS are critical elements in the correct unipolar localization of IcsA . These observations indicate a more precise role for LPS in Shigella pathogenesis. Microbios, 1995, 82(333), 217 - 25 N-terminal amino-acid sequence of beta-lactamase from Shigella flexneri UCSF-129; Campos M et al.; A beta-lactamase (EC 3.5.2.6 penicillinase, penicillin amino beta-lactam-hydrolase) was purified from Shigella flexneri USCF-129 by an efficient two-stage procedure involving chromatography in Sephadex G-75 and HPLC on a C18-reverse phase column . The homogeneity of the purified enzyme was confirmed by capillary zone electrophoresis (CZE), HPLC electrospray mass spectrometry (LC-ESMS) and amino acid sequence analyses . The highly purified enzyme was a monomeric protein with a molecular mass of 28.903 +/- 2 Da, as determined by LC-ESMS . The amino acid sequence of the first 49 N-terminal residues of this beta-lactamase revealed 100% similarity with the mature forms of the plasmid coded Escherichia coli enzymes (plasmid pBR 322 and R6K) a TEM-type beta-lactamase. Gene, 1994 Dec 2, 150(1), 67 - 70 Characterization of IS1203, an insertion sequence in Escherichia coli O111:H-; Paton AW et al.; The complete nucleotide (nt) sequence of IS1203 from Escherichia coli O111:H- strain PH has been determined . IS1203 is 1312-nt long, with imperfect 26-bp terminal inverted repeats . The two major ORFs in IS1203 encode polypeptides of 12.7 and 33.7 kDa, the latter being the putative transposase . IS1203 is closely related to IS629 of Shigella sonnei and IS3411 of E . coli . At least twelve copies of IS1203 were found in the genome of E . coli O111:H- strain PH. Carbohydr Res, 1994 Dec 2, 265(1), 121 - 7 Structural studies of the Shigella boydii type 5 O-antigen polysaccharide; Albert MJ et al.; The structure of the Shigella boydii type 5 O-antigen polysaccharide has been investigated by sugar and methylation analyses, and specific degradations . It is proposed that it is composed of hexasaccharide repeating units with the following structure . The repeating unit also contains an O-acetyl group, linked to one of the primary positions . {formula: see text} Infect Immun, 1994 Dec, 62(12), 5664 - 8 Regulation of surface presentation of IcsA, a Shigella protein essential to intracellular movement and spread, is growth phase dependent; Goldberg MB et al.; After lysing the phagocytic vacuole, Shigella spp . accumulate filaments of polymerized actin on their surface at one pole, leading to the formation of actin tails that enable them to move through the cytoplasm . We have recently demonstrated that the Shigella protein IcsA is located at the pole that is adjacent to the growing end of the actin tail (M . B . Goldberg, O . Barzu, C . Parsot, and P . J . Sansonetti, J . Bacteriol . 175:2189-2196, 1993) . Not every bacterium that is observed within the cytoplasm has an actin tail . The factors that determine when a bacterium will form a tail are unknown . Here we demonstrate that at the moment of initiation of movement, Shigella spp . are frequently in the process of division . Furthermore, the expression of IcsA on the surface of the bacteria occurs in a growth phase-dependent fashion, suggesting that the surface expression of IcsA per se determines the observed association of bacterial division with movement. Plant Mol Biol, 1994 Dec, 26(6), 2009 - 12 A 6' gentamicin acetyltransferase gene allows effective selection of tobacco transformants using kanamycin as a substrate; Gossele V et al.; 6' gentamicin acetyltransferases detoxify aminoglycoside antibiotics containing a 6' amino group . We tested whether a 6' gentamicin acetyltransferase gene (6' gat) of Shigella sp . is suitable as selectable gene in plant transformation using kanamycin (Km) as a substrate . A comparative transformation experiment using Nicotiana tabacum SR1 protoplasts showed that 6' gat is as effective for selection of transformants as the commonly used neomycin phosphotransferase II (nptII) . In stably transformed plants we detected moderate levels of the 6' gat mRNA . An enzymatic assay was developed with which the acetyltransferase activity of the protein is easily demonstrated. J Trop Pediatr, 1994 Dec, 40(6), 355 - 9 Shigellosis in Jordanian children: a clinico-epidemiologic prospective study and susceptibility to antibiotics; Rawashdeh MO et al.; During a 2-year prospective study of children hospitalized with gastroenteritis, shigellosis was detected in 66 cases (9 per cent of 726 admissions) . The age group for peak shigella incidence was 1-4 years . The incidence increased from 8 per cent in 1991, to 11 per cent in 1992 . Shigella flexneri was the most common isolate (65 per cent), followed by Shigella sonnei (17 per cent), Shigella boydi (11 per cent), and Shigella dysenteriae (7 per cent) . At presentation, 44 per cent had watery diarrhoea, followed by dysentery during hospitalization in the majority of cases . Seizures occurred in 27 per cent of cases and preceded diarrhoea in 15 per cent . Most Shigella flexneri and dysenteriae strains were resistant to co-trimoxazole, ampicillin, tetracyclin, and chloramphenicol . Nalidixic acid, gentamicin and cefotaxime were the most effective antibacterial agents . Case fatality was 3 per cent associated with strains resistant to the antibiotics used initially in the treatment. J Trop Pediatr, 1994 Dec, 40(6), 320 - 5 Double-blind comparison of oral gentamicin and nalidixic acid in the treatment of acute shigellosis in children; Islam MR et al.; To compare the efficacy of oral gentamicin with nalidixic acid in the treatment of acute shigellosis, we studied, in a double blind-trial, 79 comparable children with bloody diarrhoea of less than 72 h duration . Of them Shigella spp . were isolated in 71 patients . Patients were randomly assigned to receive either gentamicin 30 mg/kg/day or nalidixic acid 60 mg/kg/day, both given orally in four equal doses for 5 days . Stool frequency differed significantly between the groups from day two until completion of the study . Treatment failure was observed in 14 (42 per cent) patients receiving oral gentamicin compared to none of those with nalidixic acid-sensitive strains of Shigella spp . (P = 0.0002) . Although all the shigella isolates were sensitive to gentamicin in vitro, 19 (58 per cent) patients on gentamicin therapy failed to eliminate shigella organisms from stool, compared to none in the nalidixic acid treated group infected with nalidixic acid-sensitive Shigella spp . (P < 0.001) . One patient in each group had a bacteriological relapse . We conclude that gentamicin given orally was therapeutically ineffective in the treatment of acute shigellosis. J Diarrhoeal Dis Res, 1994 Dec, 12(4), 265 - 9 Detection of Shigella and enteroinvasive Escherichia coli by PCR in the stools of patients with dysentery in Thailand; Sethabutr O et al.; The rate of detection of Shigella and enteroinvasive Escherichia coli (EIEC) using a PCR technique was compared with the rate detected by standard microbiological methods (bacteriology plus hybridization of E . coli colonies with a 17 kb EIEC probe) among patients with dysentery before and after antibiotic therapy . The PCR amplified DNA sequences encoding IpaH, a multiple copy sequence located on the chromosome and the invasion plasmid . Shigella or EIEC were detected using the IpaH PCR system among 72 (61%) of 119 patients with dysentery on the first day they were seen at hospital, compared to 50 (42%) using standard microbiological methods (p = 0.006) . After three days of antibiotic therapy, IpaH sequences were detected in stools from 38 percent of patients, compared to 10 percent using standard microbiology (p < 0.001) . After seven days of therapy, the rates were 26 percent vs . 8 percent respectively (p < 0.001) . The IpaH PCR system appeared to be specific for Shigella or EIEC based on low rates of positive reactions among non-diarrhoea controls, and a strong correlation between persistently positive reactions and antibiotic resistance of bacterial isolates . IpaH sequences were detected in 10 (8%) of 119 drinking water samples from homes of patients with disease; none of these specimens were positive for Shigella or EIEC by standard microbiology . In conclusion, PCR amplification of IpaH sequences and detection of target DNA with a non-radioactive probe increased the rates of identification of Shigella and EIEC by 45% in initial clinical specimens and by nearly 300% in specimens obtained from patients receiving antibiotic therapy. Bangladesh Med Res Counc Bull, 1994 Dec, 20(3), 86 - 98 Studies on the bacterial flora of fish which are potential pathogens for human . Virulence factors of potential human pathogen isolated; Hassan MM et al.; Tests for various virulence factors, such as production of haemolysin on sheep blood agar plate, cytotoxin on HeLa cell line and enterotoxin in GM-1 ELISA and suckling mouse assay model, were done among the various strains of Aeromonas spp., Vibrio spp., Plesiomonas shigelloides and Esch . coli isolated from fresh water fish samples . Invasive properties of the isolates were also seen by using Sereny test . Haemolysin production was observed in 85.7% of Aeromonas, all (100%) of Vibrios, 13.3% of Esch . coli and none (0%) of P . shigelloides strains . Cytotoxin production was demonstrated in 60.8% of Aeromonas, 38.4% of Vibrios and none (0%) of P . shigelloides and Esch . coli strains . About 8% of Vibrio spp., were found positive for LT in GM-1 ELISA method whereas, none of the Aeromonas spp., Plesiomonas and Esch . coli . strains were found positive for LT and ST in GM-1 ELISA . By suckling mouse assay model 43.4% strains of Aeromonas were found positive for enterotoxin production whereas, strains of Vibrio spp., Plesiomonas and Esch . coli yielded negative results . Sereny test for invasive property was found negative in all the strains tested . The isolates from fish possess various virulence factors which contributes for pathogenicity in order to cause various diseases to susceptible individual. Bangladesh Med Res Counc Bull, 1994 Dec, 20(3), 117 - 22 Effect of antibiotics on serum bactericidal action on Plesiomonas shigelloides by normal human serum; Hossain MS et al.; Thirteen clinical isolates of Plesiomonas shigelloides were tested for antibiotic susceptibility of tetracycline, kanamycin-sulphate, gentamicin, erythromycin and ciprofloxacin . All the strains were susceptible to all these antibiotics . The minimal inhibitory concentration (MIC) of all these antibiotics were: Kanamycin-sulphate-MIC 0.4-10.0 micrograms/ml, tetracycline-MIC 0.25-2.4 micrograms/ml, gentamicin-MIC 2.0-12.0 micrograms/ml, erythromycin-MIC 0.5-14.0 micrograms/ml and ciprofloxacin-MIC < or = 0.006 micrograms/ml . The MIC and MBC (minimal bactericidal concentration) of the antibiotics kanamycin-sulphate, tetracycline, gentamicin, erythromycin and ciprofloxacin changed little in the presence of serum protein . Different concentrations of sub-MICs played synergistic role in serum bactericidal action on this organism. Zhongguo Zhong Yao Za Zhi, 1994 Dec, 19(12), 748 - 9, 764 {Bacteriostasis of rhizoma Coptidis combined with trimethoprim (TMPO)}; Chang MX et al.; The agar-dilution method was adopted to study contrastively the bacteriostasis of Rhizoma Coptidis and TMP, and also of the two drugs in combination . The results indicate that the combination works in good cooperation against Escherichia coli, Bacillus pyocyaneus, Staphylococcus aureus, Shigella flexneri and S . dysenteriae. Harefuah, 1994 Nov 15, 127(10), 381 - 3, 431 {Shigellosis in a primary care practice}; Ben-Noun L et al.; The epidemiological and clinical characteristics of 47 patients infected with Shigella in 3436 patients at a primary care clinic during 30 months were reviewed . Most cases were seen during the winter . The prominent clinical features were abdominal pain (91.5%), headaches (72.5%), bloody diarrhea (66%), mucoid stools (63.8%), fever (53.2%) and 75% had 4-10 stools per day . Most patients presented the first day of the illness (75%) . S . sonnei has been found the most prevalent among 4 types of shigella . Resistance to ampicillin was complete and to Resprim 95%, but to nalidixic acid and to tetracycline, 4.9% . A third of the patients were treated with oral fluids and an appropriate diet and 2/3 received antibiotics . Children between 1-4 years of age who attend kindergartens are the main risk group for Shigellosis. EMBO J, 1994 Nov 15, 13(22), 5293 - 302 The secretion of the Shigella flexneri Ipa invasins is activated by epithelial cells and controlled by IpaB and IpaD; Menard R et al.; Shigella species are enteropathogens that invade epithelial cells of the human colon . Entry into epithelial cells is triggered by the IpaB, IpaC and IpaD proteins which are translocated into the medium through the specific Mxi-Spa machinery . In vitro, Shigella cells secrete only a small fraction of the Ipa proteins, the majority of which remains in the cytoplasm . We show here that upon interaction with cultured epithelial cells or in the presence of fetal bovine serum, S.flexneri release pre-synthesized Ipa molecules from the cytoplasm into the environment . Evidence is presented that IpaB and IpaD are essential for both blocking secretion through the Mxi-Spa translocon in the absence of a secretion-inducing signal and controlling secretion of the Ipa proteins in the presence of a signal . Subcellular localization and analysis of the molecular interactions of the Ipa proteins indicate that IpaB and IpaD associate transiently in the bacterial envelope . We propose that IpaB and IpaD, by interacting in the secretion apparatus, modulate secretion. Cell, 1994 Nov 4, 79(3), 515 - 25 Extracellular association and cytoplasmic partitioning of the IpaB and IpaC invasins of S . flexneri; Menard R et al.; Shigella species cause bacillary dysentery in humans by invading colonic epithelial cells . IpaB and IpaC, two major invasins of these pathogens, are secreted into the extracellular milieu . We show here that IpaB and IpaC form a complex in the extracellular medium and that each binds independently to a 17 kDa polypeptide, IpgC, in the bacterial cytoplasm . The IpgC polypeptide was found to be necessary for bacterial entry into epithelial cells, to stabilize the otherwise unstable IpaB protein, and to prevent the proteolytic degradation of IpaC that occurs through its association with unprotected IpaB . We propose that IpgC, which is not secreted and thus acts as a molecular chaperone, serves as a receptor that prevents premature oligomerization of IpaB and IpaC within the cytoplasm of Shigella cells. Infect Immun, 1994 Nov, 62(11), 5198 - 200 Enhancement of anti-Shigella lipopolysaccharide (LPS) response by addition of the cholera toxin B subunit to oral and intranasal proteosome-Shigella flexneri 2a LPS vaccines; Orr N et al.; Addition of the cholera toxin B subunit to oral and intranasal proteosome-Shigella flexneri 2a lipopolysaccharide vaccines improved their immunogenicities . Enhancement of anti-O-Shigella immunoglobulin A levels was most evident in lung lavages following oral immunization and in lung and intestinal fluids when suboptimal doses were used with either immunization route. Infect Immun, 1994 Nov, 62(11), 5168 - 72 Construction and characterization of attenuated delta aroA delta virG Shigella flexneri 2a strain CVD 1203, a prototype live oral vaccine; Noriega FR et al.; We engineered an oral Shigella vaccine prototype that can invade intestinal epithelial cells but cannot undergo extensive intracellular replication or extend to adjacent epithelial cells . Strain CVD 1203, derived from wild-type Shigella flexneri 2a by introducing deletions in chromosomal aroA and invasion plasmid virG, was highly attenuated in the Sereny test . Two 10(9)-CFU orogastric doses (2 weeks apart) stimulated production of secretory immunoglobulin A antibodies to S . flexneri 2a and protected against conjunctival sac challenge with virulent S . flexneri 2a. Infect Immun, 1994 Nov, 62(11), 5085 - 94 Purified Shiga-like toxins induce expression of proinflammatory cytokines from murine peritoneal macrophages; Tesh VL et al.; Infections with Shiga toxin-producing Shigella dysenteriae type 1 and Shiga-like toxin (SLT)-producing Escherichia coli cause outbreaks of bloody diarrhea in which patients are at risk for developing life-threatening complications involving the renal and central nervous systems . Histopathology studies and in vitro experiments suggested that the toxins damage toxin receptor-expressing endothelial cells (EC) lining glomerular and central nervous system capillaries . In the presence of inducible host factors (cytokines), EC sensitivity to SLT toxicity was increased approximately 1 million-fold . We hypothesized that to manifest the vascular lesions characteristic of infection with toxin-producing bacteria, two signals were needed: systemic toxins and elevated proinflammatory cytokines (tumor necrosis factor alpha {TNF-alpha}, interleukin 1 {IL-1}, and IL-6) . Human EC do not secrete these cytokines when stimulated with SLTs in vitro, suggesting that additional cells may be involved in pathogenesis . Therefore, we carried out comparative analyses of the capacity of purified (endotoxin-free) SLTs and lipopolysaccharides (LPS) to induce cytokine mRNA and proteins from murine macrophages . The cells were essentially refractory to SLT cytotoxicity, expressing low to undetectable levels of toxin receptor . SLTs and LPS induced TNF activity and IL-6 expression from macrophages, although dose response and kinetics of cytokine induction differed . LPS was a more effective inducing agent than SLTs . SLT-I-induced TNF activity and IL-6 expression were delayed compared with induction mediated by LPS . IL-1 alpha production required approximately 24 h of exposure to SLTs or LPS . Macrophages from LPS-hyporesponsive C3H/HeJ mice produced low levels of TNF activity when treated with SLT-I, suggesting that LPS and SLTs may utilize separate signaling pathways for cytokine induction. Vaccine, 1994 Nov, 12(15), 1436 - 42 Safety and immunogenicity of the oral E . coli K12-S . flexneri 2a vaccine (EcSf2a-2) among Israeli soldiers; Cohen D et al.; A double-blind placebo-controlled study was carried out on the safety and immunogenicity of the oral Shigella flexneri (EcSf2a-2) vaccine among Israeli soldiers . Sixty volunteers received the vaccine and 59 received placebo . Fifty-three were given the full vaccine regimen (four doses) . Doses ranged between 4.1 x 10(8) and 1.1 x 10(9) c.f.u . Visits to the unit clinic for mild gastrointestinal symptoms were common after the first dose in vaccinees (13%) as compared with placebo recipients (5%), but the difference was not significant, p = 0.12 . Similarly, there was no difference between the groups for either gastrointestinal or non-gastrointestinal complaints reported by questionnaire . The vaccine strain was excreted by 69% and 67% of the vaccinees one day after receiving the second and the fourth doses, respectively . As judged by antibiotic susceptibility, phage typing and restriction fragment length polymorphism (RFLP), the vaccine strain emerged as genetically stable after replication in human gut and shedding . There was neither bacteriological nor serological evidence of transmission of the vaccine from vaccinees to placebo recipients . Eighteen of 26 (69.2%) and 11 of 30 (36.7%) vaccinees had significant IgA secreting cell responses 7 and 21 days after the first dose, respectively . Significant IgA or IgG serum antibody response to S . flexneri 2a LPS was detected in 30% of the vaccinees . These results support further evaluation of EcSf2a-2 vaccine protective efficacy in field studies. Int J Food Microbiol, 1994 Nov, 23(3-4), 345 - 58 Model for the combined effects of temperature, initial pH, sodium chloride and sodium nitrite concentrations on anaerobic growth of Shigella flexneri; Zaika LL et al.; A fractional factorial design was used to measure the effects and interactions of temperature (12-37 degrees C), initial pH (5.5-7.5), NaCl (0.5-4.0%) and NaNO2 (0-1000 ppm) on the anaerobic growth kinetics of Shigella flexneri in Brain-Heart Infusion broth . Anaerobic conditions were established by flushing the culture flasks with N2 . A total of 375 cultures representing 124 variable combinations were analyzed, with growth curves being generated using the Gompertz equation . Growth rates decreased with decreasing temperature, decreasing pH and increasing NaCl level . NaNO2 in combination with low temperature, low pH and high NaCl content effectively inhibited S . flexneri . Response surface analysis was used to obtain models for estimating the growth of S . flexneri in terms of temperature, initial pH, and NaCl and NaNO2 concentrations . A third-order equation using the natural logarithm transformations for the Gompertz B and M terms gave reasonable estimates of bacterial growth in response to any combination of the variables studied within the specified ranges. Antimicrob Agents Chemother, 1994 Nov, 38(11), 2668 - 70 Antimicrobial resistance of Shigella isolates causing traveler's diarrhea; Vila J et al.; Shigella isolates were identified as a cause of traveler's diarrhea in 67 (10%) of 675 patients and were tested for resistance to seven antimicrobial agents in a comparative study with those causing nontraveler's diarrhea in Spain . Ampicillin and chloramphenicol resistance was more frequent in Shigella flexneri (60 and 46%, respectively) than in Shigella sonnei (32 and 18%, respectively) and in travel-related isolates (P < 0.05 and 0.04, respectively) . Of S . sonnei isolates from patients with traveler's diarrhea, 73 and 54% showed tetracycline and trimethoprim-sulfamethoxazole resistance, respectively, compared with only 8% of isolates from patients without a history of travel to developing countries (P < 0.007 and P < 0.0002) . Low-level resistance to cephalosporins was found, whereas quinolone-resistant strains were not detected among travel-related Shigella isolates . Thus, quinolones may be an effective alternative therapy for travel-related shigellosis. Microbiology, 1994 Nov, 140 ( Pt 11), 3177 - 82 Characterization of a 38 kDa penicillin-binding protein and its possible involvement in maintaining stationary-phase cells of Shigella dysenteriae; Mahapatra S et al.; This paper reports the first attempt to characterize the penicillin-binding proteins (PBPs) of Shigella dysenteriae, an important human pathogen . The PBP pattern of the membranes of S . dysenteriae closely resembles that of Escherichia coli membranes . A 38 kDa PBP which is an important target for the penem SCH34343, the cephamycin cefoxitin and the oxacephem moxalactam, has been purified . This PBP is immunologically related to a PBP of similar molecular mass in E . coli and is present at high levels in stationary-phase cells of S . dysenteriae. Appl Environ Microbiol, 1994 Oct, 60(10), 3573 - 8 Methionine uptake and cytopathogenicity of viable but nonculturable Shigella dysenteriae type 1; Rahman I et al.; A pathogenic strain of Shigella dysenteriae type 1 was selected for study to elucidate the physiology and potential pathogenicity of organisms in the viable but nonculturable (VBNC) state in the environment . Studies in our laboratory have shown that S . dysenteriae type 1 survives in laboratory microcosms in the VBNC state for long periods of time, i.e., more than 6 months . VBNC cells of S . dysenteriae type 1 were found to retain cytopathogenicity for cultured HeLa cells . To determine whether VBNC S . dysenteriae type 1 expressed protein after loss of culturability, 35S-labelled methionine was added to suspensions of VBNC cells . Total cellular proteins were extracted and examined by autoradiography . Results indicate that VBNC S . dysenteriae type 1 is capable of both active uptake of methionine and incorporation of methionine into protein . Amino acid uptake and protein synthesis substantiate the viability of cells of S . dysenteriae type 1 in the VBNC state, i.e., although the cells are unable to be cultured on laboratory media by standard bacteriological methods, the cells remain metabolically active . Furthermore, VBNC cells of S . dysenteriae type 1 may pose a potential public health hazard that has not yet been recognized. J Med Microbiol, 1994 Oct, 41(4), 279 - 81 Effect of subinhibitory concentrations of antimicrobial agents on virulence factors of Shigella flexneri 2a and Escherichia coli O124; Tetz VV et al.; The effect of subinhibitory concentrations of rifampicin, chloramphenicol, tetracycline and nalidixic acid on the interaction of Shigella flexneri 2a and Escherichia coli O124 with HeLa cells was examined . Antimicrobial agents altered adhesion, penetration and intracellular multiplication of the bacteria, as well as re-infection of adjacent cells . Chloramphenicol increased the virulence of the bacterial strains whereas nalidixic acid, tetracycline and rifampicin diminished it. J Exp Med, 1994 Oct 1, 180(4), 1307 - 19 Acute inflammation causes epithelial invasion and mucosal destruction in experimental shigellosis; Perdomo OJ et al.; The gram-negative pathogen Shigella flexneri causes bacillary dysentery, an invasive disease of the human colonic mucosa . A major characteristic of the infectious process is the occurrence of an acute inflammatory reaction of mucosal tissues which is generally consequence of primary invasion and destruction of colonic epithelial cells by the pathogen . Confirming in vitro demonstration that S . flexneri is unable to invade the apical pole of colonic cells and that polymorphonuclear (PMN) cells may assist them in reaching the basal side of epithelial cells where they can invade, we have provided here in vivo evidence that S . flexneri enters the epithelial barrier essentially through the dome of lymphoid follicles at the early stage of infection and that subsequent invasion and destruction of the epithelium is primarily due to immigration of leukocytes, particularly PMN that destroy cohesion of the epithelial barrier . These conclusions are based on experiments carried out in infected rabbit ligated intestinal loops, with some animals treated by an anti-CD18 monoclonal antibody that blocked immigration of leukocytes into infected tissues. Infect Immun, 1994 Oct, 62(10), 4333 - 8 Purification, pore-forming ability, and antigenic relatedness of the major outer membrane protein of Shigella dysenteriae type 1; Roy S et al.; The major outer membrane protein (MOMP), the most abundant outer membrane protein, was purified to homogeneity from Shigella dysenteriae type 1 . The purification method involved selective extraction of MOMP with sodium dodecyl sulfate in the presence of 0.4 M sodium chloride followed by size exclusion chromatography with Sephacryl S-200 HR . MOMP was found to form hydrophilic diffusion pores by incorporation into artificial liposome vesicles composed of egg yolk phosphatidylcholine and dicetylphosphate, indicating that MOMP of S . dysenteriae type 1 exhibited significant porin activity . However, the liposomes containing heat-denatured MOMP were barely active . The molecular weight of MOMP found by size exclusion chromatography was 130,000, and in sodium dodecyl sulfate-10% polyacrylamide gel it moved as an oligomer of 78,000 molecular weight . Upon boiling, fully dissociated monomers of 38,000 molecular weight were seen for S . dysenteriae type 1 . However, among the four Shigella spp., the monomeric MOMP generated upon boiling ranged from 38,000 to 35,000 in molecular weight . Antibody raised in BALB/c mice immunized with MOMP of S . dysenteriae type 1 reacted strongly with purified MOMP of S . dysenteriae type 1 in an enzyme-linked immunosorbent assay (ELISA) . The antibody reacted with whole-cell preparations of S . dysenteriae type 1 in an ELISA, suggesting that MOMP possessed surface components . Moreover, MOMP could be visualized on the bacterial surface by immunoelectron microscopy with anti-MOMP antibody . S . dysenteriae type 1 MOMP-specific immunoglobulin eluted from MOMP bound to a nitrocellulose membrane was found to cross-react with MOMP preparations of S . flexneri, S . boydii, and S . sonnei, indicating that MOMPs were antigenically related among Shigella species . The strong immunogenicity, surface exposure, and antigenic relatedness make MOMP of Shigella species an immunologically significant macromolecule for study. Antimicrob Agents Chemother, 1994 Oct, 38(10), 2488 - 91 Detection of 4-quinolone resistance mutation in gyrA gene of Shigella dysenteriae type 1 by PCR; Rahman M et al.; To study 4-quinolone resistance, the N-terminal coding region of gyrA from nalidixic acid-susceptible and -resistant isolates of Shigella dysenteriae type 1 was amplified by PCR, cloned, and sequenced . DNA sequence analysis of gyrA from nalidixic acid-resistant isolates revealed a C-to-T transition at nucleotide position 248 leading to a Ser-83-to-Leu substitution which was absent in susceptible clinical isolates . Direct HinfI digestion of PCR-amplified DNA detected similar mutations . Thus, DNA gyrase A subunit mutation Ser-83 to Leu is implicated in 4-quinolone resistance in S . dysenteriae type 1. Immunol Cell Biol, 1994 Oct, 72(5), 419 - 26 Modulation and recovery of immune response of BALB/c mice to Shigella dysenteriae antigens after cyclophosphamide treatment; Mishra KK et al.; We have analysed the suppressive effect of cyclophosphamide, when given in vivo, on the antibody response of BALB/c mice against Shigella dysenteriae antigens using ELISA and immunoblot . Out of various protocols tried, it was found that co-injection of cyclophosphamide at 150 mg/kg bodyweight, i.p., at the time of antigen administration and then after a lapse of 24 h during both primary and secondary immunizations, was the most effective in suppressing antibody response of mice . Analysis of sera by ELISA demonstrated the presence of some antibodies to S . dysenteriae antigens after secondary immunization, but immunoblot analysis using the same sera revealed complete suppression of antibody response . Animals whose antibody response was almost completely suppressed after two immunizations with co-injection of cyclophosphamide, when immunized again after the lapse of 14 days from the date of secondary immunization with Shigella antigens but without administration of cyclophosphamide, partially recovered their ability to respond to the same antigens . This protocol can now be used in mice to analyse the hierarchy of immunogenic epitopes present in a complex mixture of antigens. J Clin Microbiol, 1994 Oct, 32(10), 2549 - 52 Shigella sonnei strains isolated from U.S . summer students in Guadalajara, Mexico, from 1986 to 1992; Scerpella EG et al.; Plasmid DNA analysis and antibiotic susceptibilities were used to study strains of Shigella sonnei isolated from U.S . travelers to Guadalajara, Mexico, over a period of seven years (1986 to 1992) . One hundred sixty-one isolates were analyzed . By the use of cluster analysis, eight different plasmid profiles were identified during this interval . At any point in time, three to seven different plasmid profiles were present in this population . The introduction of strains that carried a new plasmid with a molecular mass of 5.1 MDa was coincidental with an increase in isolation of S . sonnei in 1988 . This new plasmid was present in 87.5% of the isolates that were resistant to chloramphenicol . Shigellosis in Guadalajara follows a pattern of hyperendemic transmission with transient peaks of high-frequency isolation of S . sonnei . This pattern results from the concurrent presence of a heterogeneous group of strains as opposed to the widespread transmission of one or a few clones. J Clin Microbiol, 1994 Oct, 32(10), 2460 - 3 Nucleotide sequence analysis of enteropathogenic Escherichia coli (EPEC) adherence factor probe and development of PCR for rapid detection of EPEC harboring virulence plasmids; Franke J et al.; The 1-kb BamHI-SalI fragment from plasmid pMAR2 termed the enteropathogenic Escherichia coli (EPEC) adherence factor (EAF) probe was cloned in pUC19 and pK18 . The nucleotide sequence of this fragment was determined, and a set of primers was designed to amplify a 397-bp region associated with pMAR2 by PCR . An analysis of the whole EAF sequence with database libraries indicated no significant homology to any known genes . However, between bases 701 and 787 of the fragment, an 82.8% homology between the EAF and the insertion sequence IS630 of Shigella sonnei exists . The results of PCR with primers of the EAF sequence demonstrated that all of the 151 EAF probe-positive EPEC strains with localized adherence to HEp-2 cells yielded positive EAF PCR results . In contrast, none of the 277 EAF probe-negative strains reacted to the EAF PCR . In addition, the PCR assay was successfully used to generate vector-free digoxigenin-labeled EAF fragments that gave valid results in colony blot hybridization assays . The EAF PCR appears to be a specific and efficient method for the detection of EPEC strains carrying the EAF plasmids. Rev Latinoam Microbiol, 1994 Oct-Dec, 36(4), 227 - 30 {Analysis of 1185 strains of Shigella isolated in Mexico from 1982 to 1993}; Gutierrez-Cogco L et al.; During the period from 1982 to 1993, 1185 Shigella strains from the National Network of Diarrhoeal Laboratories were sent to the Enteric Bacteriology Laboratory of INDRE . These strains from patients of various ages with diarrhoeal illness were serologically confirmed . The frequency was as follows: S . flexneri (61.35%), S . sonnei (26%), S . dysenteriae (6.4%) and S . boydii (6.2%) . S . dysenteriae 1 is an epidemiologicaly important species because it has caused diarrhoeal outbreaks on the southern border of Mexico that later spread through Central America . It must be considered that the 20 isolates obtained in 1989 were from an intentional search focused on S . dysenteriae . Authors pretend to continue with epidemiological surveillance focused on Shigella and intensify the intentional search in order to identify possible human or environmental S . dysenteriae 1 reservoires. MMWR Morb Mortal Wkly Rep, 1994 Sep 30, 43(38), 701 - 3 Health status of displaced persons following Civil War--Burundi, December 1993-January 1994; Interleukin 1 is released by murine macrophages during apoptosis induced by Shigella flexneri; Unite de Pathogenie Microbienne Moleculaire, Institut National de la Sante et de la Recherche Medicale U389, Institut Pasteur, Paris, FrancePeritoneal macrophages undergoing apoptosis induced by Shigella flexneri infection release the inflammatory cytokine interleukin 1 (IL-1), but not IL-6 or tumor necrosis factor alpha (TNF alpha) . Wild type shigella causes a very fast and significant release of IL-1 from prestimulated peritoneal macrophages, before the cell's integrity is compromised . Both IL-1 alpha and IL-1 beta are released, IL-1 beta in its mature processed form . IL-1 is released from presynthesized cytoplasmic pools . These results demonstrate that bacteria-induced apoptosis of macrophages may play an active role in vivo by releasing IL-1, which in turn mediates an early inflammatory response in epithelial tissues. Mt Sinai J Med, 1994 Sep, 61(4), 367 - 8 Fatal Shigella sepsis in a neutropenic patient; Kenet G et al.; Bacteremia during infection with Shigella is relatively rare and usually self-limited . Bacteremia during shigellosis bearing a high fatality rate has been reported in young infants and in persons with malnutrition or with the acquired immunodeficiency syndrome . We report a case of Shigella sonnei septicemia in a severely neutropenic patient who had fever, abdominal pain, diarrhea, malnutrition, and dehydration . She died after five days despite intensive care . We emphasize that Shigella should be considered among the possible pathogens causing sepsis in neutropenic patients. J Diarrhoeal Dis Res, 1994 Sep, 12(3), 208 - 13 Indicators for antibiotic therapy in invasive bacteria diarrhoea; Ismail R et al.; The objective of the study was to determine the clinical indications for antibiotic therapy in diarrhoeal diseases (DD) in 619 children aged 6 to 59 months who were evaluated during a clinical study of diarrhoea . The patients were seen at the outpatient clinic of the Palembang General Hospital from May 1991 through March 1992 . Data concerning abdominal pain, pain during defecation, fever, status of breastfeeding, vomiting, mucoid stool, bloody stool, abdominal distention, stool leucocytes and erythrocytes were analyzed to determine their predictive value (PPV) in relation to the bacterial isolation of pathogen in the stool . All clinical variables examined had a low PPV for isolation of any enteric pathogen, including Shigella . The PPV of grossly bloody diarrhoea was 20.8% (95% confidence limits 17.6%-24%), and that of body temperature (> 37.5 degrees C) was 19.6% . When the stool leucocytes were 10 or more per high-power microscopic field (HPMF), the PPV was 22.2%; of erythrocytes found microscopically in the stool, 19.6% . We recommend that those patients with bloody stools and mucoid stools with temperatures of 37.5 degrees C get antibiotics (22%) . Second, those patients having 10 or more leucocytes per HPMF plus those with red cells in stools (regardless of the number) should receive either antibiotics and or amoebicides if amoebae are present (5%). Fam Pract, 1994 Sep, 11(3), 318 - 24 Latino health in Los Angeles: family medicine in a changing minority context; Hayes-Bautista DE et al.; The inner city population of the Los Angeles county has rapidly become largely Latino . The 3.3 million Latinos living in the county in 1990 had much higher poverty rates and lower educational attainment rates than Anglo (non-Hispanic white) or blacks . The health indicators of the three groups are compared for 1990 . In birth outcome, although Latinos were the least likely to receive care in the first trimester, Latinos and Anglos had identical rates of low birth weight babies, and lower rates than blacks . Latino infant mortality was the lowest of the three . The age-adjusted death rates showed that Latinos have a lower overall death rate than Anglos or blacks, and lower specific rates for heart disease, cancer, AIDS and stroke . Latinos did have higher death rates than Anglos for accidents, homicides, cirrhosis and diabetes . Latinos had incidence rates of gonorrhoea and syphilis similar to Anglos and lower than blacks . The communicable disease rates for Latinos was many times higher than Anglos or blacks, including those for measles, shigellosis, giardiasis and hepatitis A . Implications for family medicine are discussed. J Accid Emerg Med, 1994 Sep, 11(3), 168 - 71 Acute bacterial diarrhoea in the emergency room: therapeutic implications of stool culture results; Kaminski N et al.; Empiric treatment with ciprofloxacin and norfloxacin has been recommended recently for patients with acute diarrhoeal disease . In a retrospective 6-month study period the results of stool cultures from 209 patients with acute diarrhoea admitted to the emergency room were analysed . Seventy-eight cultures (37%) were positive for one or more bacteria . Shigella was the most commonly isolated pathogen (68%) . Shigella sonnei comprised 72% and Shigella flexneri 19% of all the bacterial isolates . While no antimicrobial resistance to ciprofloxacin was found for both Shigella species, only 36 and 26% of the Shigella isolates were sensitive to ampicillin and trimethoprim-sulfamethoxazole (TMP-SMZ), respectively . These findings point out to the emergence of drug resistance to commonly used antimicrobial drugs . Shigella's high sensitivity to the newer quinolones should make this the treatment of choice for the very sick patient, although physicians should be cautioned to the fact that indiscriminate use of this drug could result in the emergence of resistance similar to that noted with ampicillin and TMP-SMZ. JAMA, 1994 Aug 3, 272(5), 377 - 81 Infectious disease surveillance during emergency relief to Bhutanese refugees in Nepal; Marfin AA et al.; OBJECTIVE--To implement simplified infectious disease surveillance and epidemic disease control during the relocation of Bhutanese refugees to Nepal . DESIGN--Longitudinal observation study of mortality and morbidity . SETTING--Refugee health units in six refugee camps housing 73,500 Bhutanese refugees in the eastern tropical lowland between Nepal and India . INTERVENTIONS--Infectious disease surveillance and community-based programs to promote vitamin A supplementation, measles vaccination, oral rehydration therapy, and early use of antibiotics to treat acute respiratory infection . MAIN OUTCOME MEASURES--Crude mortality rate, mortality rate for children younger than 5 years, and cause-specific mortality . RESULTS--Crude mortality rates up to 1.15 deaths per 10,000 persons per day were reported during the first 6 months of surveillance . The leading causes of death were measles, diarrhea, and acute respiratory infections . Surveillance data were used to institute changes in public health management including measles vaccination, vitamin A supplementation, and control programs for diarrhea and acute respiratory infections and to ensure rapid responses to cholera, Shigella dysentery, and meningoencephalitis . Within 4 months of establishing disease control interventions, crude mortality rates were reduced by 75% and were below emergency levels . CONCLUSIONS--Simple, sustainable disease surveillance in refugee populations is essential during emergency relief efforts . Data can be used to direct community-based public health interventions to control common infectious diseases and reduce high mortality rates among refugees while placing a minimal burden on health workers. J Bacteriol, 1994 Aug, 176(15), 4627 - 34 vacC, a virulence-associated chromosomal locus of Shigella flexneri, is homologous to tgt, a gene encoding tRNA-guanine transglycosylase (Tgt) of Escherichia coli K-12; Durand JM et al.; The genetic determinants required for invasion of epithelial cells by Shigella flexneri and for the subsequent bacterial spreading are encoded by the large virulence plasmid . Expression of the virulence genes is under the control of various genes on the large plasmid as well as on the chromosome . We previously identified one of the virulence-associated loci near phoBR in the NotI-C fragment of the chromosome of S . flexneri 2a YSH6000 and designated the locus vacC . The vacC mutant showed decreased levels of IpaC, and IpaD proteins as well as transcription of ipa, an operon essential for bacterial invasion (N . Okada, C . Sasakawa, T . Tobe, M . Yamada, S . Nagai, K . A . Talukder, K . Komatsu, S . Kanegasaki, and M . Yoshikawa, Mol . Microbiol . 5:187-195, 1991) . To elucidate the molecular nature of the vacC locus, we cloned the vacC region from YSH6000 on a 1.8-kb SalI-BamHI DNA fragment . The nucleotide sequence of the 1,822-bp vacC clone was highly (> 98%) homologous to the tgt region of Escherichia coli K-12, which is located at 9.3 min on the linkage map . Complementation tests indicated that the vacC function was encoded by an open reading frame expressing a 42.5-kDa protein, which corresponded to the tgt gene of E . coli K-12, coding for tRNA-guanine transglycosylase (Tgt) (K . Reuter, R . Slany, F . Ullrich, and H . Kersten, J . Bacteriol . 173:2256-2264, 1991) . The cloned tgt gene from E . coli K-12 restored the virulence phenotype to the vacC mutant of YSH6000 . Characterization of the vacC mutant indicated that levels of VirG, a protein essential for bacterial spreading, and VirF, the positive regulator for the expression of the virG and ipaBCD operons, decreased significantly compared with those of the wild type . Similar phenotypic changes occurred in vacC mutants constructed by insertion of a neomycin resistance gene in shigellae and enteroinvasive E . coli strains, consistent with the hypothesis that the vacC (tgt) gene contributes to the pathogenicity of Shigella flexneri. Isr J Med Sci, 1994 Aug, 30(8), 604 - 10 The effect of shiga toxin and sonicates of Shigella isolates from children with neurologic manifestation on neuroblastoma cell lines; Ashkenazi S et al.; Although neurologic manifestations are frequent during childhood shigellosis, their pathogenesis is unclear and controversial . Shiga toxin and other cytotoxins are often implicated, but their effect on neuronal cells has not been determined . We examined the effect of purified Shiga toxin and sonicates of Shigella isolates from children with neurologic symptoms on well-characterized human neuroblastoma cells in vitro . Quantitative determinations showed high cytotoxicity of Shiga toxin on HeLa cells (1.2 x 10(6) CD50/mg purified toxin), but no effect on LA-N-1, LA-N-5 and IMR neuroblastoma cell lines . Pretreatment with tumor necrosis factor, which increases expression of the Shiga toxin receptor, globotriosyl ceramide, in endothelial cells and enhanced Shiga toxin cytotoxicity, did not affect the susceptibility of neuroblastoma cells to the toxin . Low dilutions (up to 1:16-1:64) of sonicates of Shigella isolates from children with neurologic symptoms caused agglutination of neuroblastoma cells, but no cell killing was observed morphologically . This study shows that Shiga toxin does not exhibit cytotoxic activity on the human neuroblastoma cell lines examined, neither do sonicates of relevant Shigella strains . The mechanism and significance of the agglutination activity on neuroblastoma cells should be further studied. Int J Epidemiol, 1994 Aug, 23(4), 856 - 62 Family latrines and paediatric shigellosis in rural Bangladesh: benefit or risk? Ahmed F, Clemens JD, Rao MR, Banik AK. BACKGROUND . The potential benefits of installing excreta disposal facilities on the burden of paediatric diarrhoea in less-developed settings remain controversial . We conducted a longitudinal study to evaluate whether family latrines are associated with interruption of the transmission of shigellosis to younger children in rural Bangladesh . METHODS . We prospectively studied 1529 children under 5 years of age exposed to index cases of Shigella dysentery . In all 219 children with culture-proven shigellosis detected during 1 month of follow-up were compared with 1310 control children who did not develop shigellosis or Shigella-negative dysentery . RESULTS . Overall, the presence of a family latrine appeared to be associated with a higher, not a lower, risk of paediatric shigellosis (adjusted odds ratio (ORa) = 1.37, 95% confidence interval (CI): 0.99-1.89) . While use of a pit or sanitary latrine revealed no evidence of a protective association (ORa = 0.96, 95% CI: 0.43-2.15), use of a hanging latrine in which faeces were discharged directly onto the ground or into a body of water was associated with a notable increase of risk (ORa = 1.42, 95% CI: 1.02-1.98, P < 0.05) . CONCLUSIONS . While cautioning that installation of sanitary latrines may not be sufficient to reduce the burden of paediatric shigellosis in less-developed settings, these data suggest that eliminating unsanitary latrines constitutes a potentially important intervention in its own right in these settings. Mol Microbiol, 1994 Aug, 13(3), 395 - 402 The actin-based motility of the facultative intracellular pathogen Listeria monocytogenes; Cossart P et al.; The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular parasite that invades and multiplies within diverse eukaryotic cell types . An essential pathogenicity determinant is its ability to move in the host cell cytoplasm and to spread within tissues by directly passing from one cell to another . The propulsive force for intracellular movement is thought to be generated by continuous actin assembly at the rear end of the bacterium . Moving bacteria that reach the plasma membrane induce the formation of long membranous protrusions that are internalized by neighbouring cells, thus mediating the spread of infection . The unrelated pathogens Shigella and Rickettsia use a similar process of actin-based motility to disseminate in infected tissues . This review focuses on the bacterial and cellular factors involved in the actin-based motility of L . monocytogenes. Acta Paediatr Jpn, 1994 Aug, 36(4), 450 - 2 Neonatal Plesiomonas shigelloides septicemia and meningitis: a case and review; Fujita K et al.; A 3 day old neonate with septicemia and meningitis due to Plesiomonas shigelloides is described . We could not detect the source of this infection . The patient was treated with cefotaxime and survived without sequelae . Nine previously reported cases with this infection were reviewed. Kansenshogaku Zasshi, 1994 Aug, 68(8), 973 - 6 {Shigella boydii strains having a provisional serovar isolated from travellers' diarrhea in Tokyo}; Matsushita S et al.; Two Shigella strains (85-634 and 94-30) isolated from two sporadic travellers with diarrhea who returning to Tokyo from abroad, did not react to any antisera to Shigella prepared commercially . These strains had the typical biochemical characteristics of S . boydii and were biochemically identical, and were positive in the Sereny test and other tests for invasiveness; these indicate that they can cause shigellosis in humans . The results of serological analyses using the antisera to 6 kinds of provisional Shigella serovars, showed that both strains had provisional S . boydii serovar E16553 . Although the serovar has been reported by Gross et al in the United Kingdom, this may be the first report in Japan. Mol Cell Probes, 1994 Aug, 8(4), 285 - 90 Detection of shigellae, enteroinvasive and enterotoxigenic Escherichia coli using the polymerase chain reaction (PCR) in patients returning from tropical countries; Luscher D et al.; We have used the polymerase chain reaction (PCR) to detect shigellae, EIEC and ETEC in stool specimens of diarrhoeic patients returning from tropical countries . As compared to culture (7.1% positive specimens), which recognizes only Shigella strains, PCR performed on bacterial growth from directly inoculated MacConkey agar plates and directed against virulence-associated genes present in both Shigella and EIEC was positive in 19.8% of the samples . We assumed that these additional positive results represent true rather than false positive samples because identical results for each single specimen were obtained using two different PCR systems and because positive results (culture as well as PCR) were exclusively found in patients with recent travel but not in those who acquired diarrhoea in a developed country where these organisms are not endemic . PCR detecting LT- and ST-specific sequences was positive in 18.5% of the patients with recent travel . Again no positive cases were identified in controls . Combining PCR and culture results, at least one bacterial pathogen was found in more than 50% of the patients with recent travel . We conclude that PCR is superior to culture methods for the detection of Shigella, EIEC and ETEC in travel-associated diarrhoea. Zh Mikrobiol Epidemiol Immunobiol, 1994 Aug-Sep, Suppl 1, 34 - 6 {The persistence of Shigella sonnei in epithelial tissue in Serény's model}; Pozhalostina LV et al.; The duration of persistence of S . sonnei in the tissues of a guinea pig eye (Sereny's model) has been studied . Bacteriological and histological investigations made with the use of fluorescent antibody techniques have revealed that S . sonnei can be preserved in macrophages (histiocytes) and intercellular space of the eye epithelium for a long time (up to 277 days) . The injection of ACTH or Shigella vaccine into the animals may provoke the exacerbation of the infectious process and the release of the infective agent. J Antimicrob Chemother, 1994 Aug, 34(2), 253 - 9 Antibiotic resistance patterns and plasmid profiles for Shigella spp . isolated in Cordoba, Argentina; Brito-Alayon NE et al.; The antimicrobial resistance patterns and plasmid profile analyses for 30 Shigella spp . isolated in Cordoba, Argentina, were determined . Most strains were resistant to multiple antibiotics, particularly traditional agents such as ampicillin, chloramphenicol and trimethoprim . All isolates harboured at least one plasmid (range 1-12), the plasmid profiles differing in every case . Nineteen strains transferred all or some of their resistance determinants by conjugation. Bangladesh Med Res Counc Bull, 1994 Aug, 20(2), 43 - 51 Studies on the bacterial flora of fish which are potential pathogens for human . Isolation of various potential human pathogenic organisms from different parts of fish and their significance in initiating human diseases; Hassan MM et al.; Freshwater fish of different categories, collected from market of Dhaka City of Bangladesh, were studied for the bacterial flora . Potential human pathogens were isolated from about eighty-five percent of the fish studied . Organisms isolated were Aeromonas spp., (69.2%), Vibrio spp., (42.3%), Plesiomonas shigelloides (35.9%) and Escherichia coli (16.7%) . The high association of potential human pathogens among the freshwater fish suggest that if fish are handled improperly or if consumed undercooked or uncooked may cause various diseases to susceptible individual. J Pediatr, 1994 Jul, 125(1), 14 - 22 Shigellosis in neonates and young infants; Huskins WC et al.; To determine the clinical features and outcome of shigellosis in young infants, we reviewed the hospital records of 159 infants < or = 3 months of age (including 30 neonates) and 159 children 1 to 10 years of age with shigellosis who were admitted to the Diarrhoea Treatment Centre in Dacca, Bangladesh . Infants more commonly had a history of nonbloody diarrhea (82.8% vs 42.7%; p < 0.001), moderate or severe dehydration (59.9% vs 32.1%; p < 0.001), or bacteremia (12.0% vs 5.0%; p = 0.027) and less commonly had fever (32.7% vs 58.6%; p < 0.001), abdominal tenderness (1.9% vs 12.6%; p < 0.001), or rectal prolapse (0% vs 8.3%; p = 0.001) . Infections caused by Shigella boydii (20.8% vs 6.3%; p < 0.001) and Shigella sonnei (7.5% vs 1.3%; p = 0.006) were more common, and Shigella dysenteriae type 1 (9.4% vs 31.4%; p < 0.001) infections were less common in infants than in older children; the proportion of Shigella flexneri infections was equivalent in the two groups (59.1% vs 60.4%) . Infants were twice as likely to die as older children (16.4% vs 8.2%; p = 0.026) . Only 17 infants (14.3%) were being exclusively breast fed at the onset of their illness . In a multiple logistic regression analysis, independent predictors of death in infants were gram-negative bacteremia, ileus, decreased bowel sounds, hyponatremia, hypoproteinemia, and a lower number of erythrocytes detected on microscopic examination of stool specimens . Diarrhea management algorithms that rely only on clinical findings of dysentery to diagnose and treat shigellosis are likely to be unreliable in this high-risk age groupPIP: Findings are reported from a study conducted to determine the clinical features and outcome of shigellosis in young infants . The authors reviewed the hospital records of 159 infants of no greater than age 3 months and those of 159 children aged 1-10 years with shigellosis who were admitted to the Diarrhea Treatment Center in Dacca, Bangladesh . 82.8% of infants had a history of nonbloody diarrhea, 59.9% moderate or severe dehydration, 12% bacteremia, 32.7% fever, 1.9% abdominal tenderness, and 0% rectal prolapse . 42.7% of children had a history of nonbloody diarrhea, 32.1% moderate or severe dehydration, 5.0% bacteremia, 58.6% fever, 12.6% abdominal tenderness, and 8.3% rectal prolapse . Infections caused by Shigella boydii and Shigella sonnei were more common in infants, while Shigella dysenteriae type 1 infections were less common in infants than in older children . There was an equivalent proportion of Shigella flexneri infections in the two groups . Infants were twice as likely to die as older children . Only 17 infants were being exclusively breastfed at the onset of their illness . Multiple logistic regression analysis identified the independent predictors of death among infants to be gram-negative bacteremia, ileus, decreased bowel sound, hyponatremia, hypoproteinemia, and a lower number of erythrocytes detected on the microscopic examination of stool specimens . Diarrhea management algorithms which rely exclusively upon clinical findings of dysentery to diagnose and treat shigellosis are likely to be unreliable in this high-risk age group . J Bacteriol, 1994 Jul, 176(13), 4187 - 91 A role for H-NS in the thermo-osmotic regulation of virulence gene expression in Shigella flexneri; Porter ME et al.; The role of the hns gene (coding for the curved-DNA-binding protein H-NS) in the thermo-osmotic regulation of Shigella flexneri virulence gene transcription was investigated . Two structural genes, mxiC and icsB, which are transcribed divergently on the high-molecular-weight virulence plasmid, were found to be transcriptionally inhibited in cultures grown in a low-osmolarity medium, even at the inducing temperature . This repression was relieved by inactivation of the hns gene, establishing a role for hns in the osmotic as well as the thermal regulation of invasion gene expression . The physiological relevance of this finding is discussed. J Bacteriol, 1994 Jul, 176(13), 4168 - 72 Cloning and sequencing of sarA of Staphylococcus aureus, a gene required for the expression of agr; Cheung AL et al.; To evaluate the effect of a sar mutation on the agr locus, Northern (RNA) blotting was performed to determine the levels of RNAIII, the agr regulatory molecule, in two isogenic pairs of Staphylococcus aureus strains . Our results demonstrated that RNAIII was either significantly diminished or absent in both sar mutants compared with the parents . The RNAIII level was partially restored in sar mutants complemented with an intact sar gene (designated sarA) . Additionally, we were able to complement selected sar phenotypes with a plasmid carrying RNAIII (pRN6735) . These studies suggest that the sarA gene is necessary for the optimal expression of agr . The sarA gene of strain RN450 was subsequently cloned and sequenced . Sequence analysis revealed an open reading frame of 372 bp with a predicted molecular size of 14,718 Da and a deduced pI of 8.52 . The deduced protein sequence has a predominance of charged residues (33%) and shares sequence similarity with the virF gene of Shigella flexneri. Pediatr Infect Dis J, 1994 Jul, 13(7), 597 - 602 Asymptomatic Shigella infections in a cohort of Mexican children younger than two years of age; Guerrero L et al.; The proportion of Shigella infections that occur asymptomatically in young children has not been established . A community-based cohort study of 367 infants was followed prospectively by weekly home visits from January, 1990, through December, 1991 . Stool samples were collected weekly and when diarrhea occurred and were tested for Shigella and other enteropathogens . There were 2925 child months of observation and 65 episodes of Shigella infection . There were 3.1 episodes/100 child months during the warm season (May through September) and 0.97 episode/100 child months during the cold season . Shigella infections were rare during the first 6 months of life but increased with age (P < 0.0001) . Overall 55% of detected infections were asymptomatic . The proportion of infections that were asymptomatic increased as age increased (P < 0.01) . Symptom status was not significantly associated with Shigella species or season . All isolates from symptomatic and asymptomatic children had the 120- to 140-megadalton virulence plasmid . We conclude that infections with virulent strains of Shigella are commonly asymptomatic in Mexican children during the first 2 years of lifePIP: During January 1990-December 1991, each week, field workers visited the home of 367 children aged 0-24 months from a periurban area southwest of Mexico City (San Pedro Martir and San Andres Totoltepec, Tlalpan) and collected stool specimens from them to determine whether Shigella infections are often asymptomatic . The crude incidence rate of diarrhea, regardless of etiology, was 29 episodes/100 child months during the warmer and rainy months (May-September), while it was 21 episodes/100 child months for the rest of the year (October-April) (relative risk {RR} =1.38) . 53 of all children (l4%) had 65 Shigella infections . The overall monthly incidence of symptomatic and asymptomatic Shigella infection was higher during May-September than October-April (3.13 vs . 0.97 episodes/100 children; RR = 3.22) . 55% of all Shigella infections (36) were asymptomatic . 32% developed secretory-type diarrhea and 13% had blood present in the stool . The incidence of Shigella infections grew as did the age (0.4-8.2 episodes/100 child months for 0-6 month olds to 18-24 month olds; p 0.0001) . The proportion of asymptomatic Shigella infections also increased with age (33% for 0-6 month olds, 40% for 7-12 month olds, 46% for 13-18 month olds, and 78% for 18-24 month olds; p 0.01) . Shigella sonnei, S . flexneri, and S . boydii were the only species detected . The 120-140 megadalton virulence plasmid was present in all isolates from asymptomatic and symptomatic children . Mixed infections were rather common in both asymptomatic (47%) and symptomatic (45%) children . Among infants aged less than 12 year months, breast feeding infants were less likely to be infected with Shigella than nonbreast feeding infants (RR = 2.41) . On the other hand, among children aged 12-24 months, nonbreast feeding was associated with a lower risk of Shigella infection (RR = 0.69) . These findings show that Shigella infections in Mexican children aged 0-24 months range from asymptomatic infections to secretory diarrhea to bloody diarrhea . Res Commun Mol Pathol Pharmacol, 1994 Jul, 85(1), 109 - 12 LPS injected into the pregnant rat late in gestation does not induce fetal endotoxemia; Goto M et al.; Endotoxin is abortifacient . Abortion may be due to maternal, fetal or combined endotoxemia . The present study was performed to evaluate if fetal rat endotoxemia was induced by maternal endotoxemia in late gestation . An intraperitoneal injection of smooth lipopolysaccharide (Escherichia coli LPS and Shigella flexneri LPS) or rough LPS (Rc mutant Escherichia coli LPS) induced Limulus activity in maternal plasma, but not fetal plasma . These results suggest that fetal rat endotoxemia is not induced during maternal endotoxemia . Thus, the abortion may not be due to fetal endotoxemia. Zhongguo Zhong Xi Yi Jie He Za Zhi, 1994 Jul, 14(7), 400 - 2 {Clinical study in treating intractable ulcerative colitis with traditional Chinese medicine}; Chen ZS et al.; Clinical double blind study in treating 153 intractable ulcerative colitis with Chinese medicinal herbs was conducted, the patients were randomly assigned to three groups . Group I is administered with Jian Pi Ling (JPL) tablet with retention-enema of Radix Sophorae Flavescentis and Flos Sophora (RSF-FS) decoction per night, group II with salicylazosulfapyridine (SASP) and retention-enema of dexamethasone, group III with placebo and retention-enema of decoction as that in group I . After 90 days every patients were checked by means of fibro-enteroscope, pathologic and immunologic parameters . The results: the curative rates of group I, II, III, were 53.1%, 27.7% and 19.0%, the total effective rates were 85.9%, 59.6% and 45.2% respectively . By comparison among groups, the efficacy of group I was the best (P < 0.01) . The check of T and B lymphocyte subpopulation showed the B lymphocyte of group I markedly decreased, OKT3 and OKT8 obviously increased, the ratio of OKT4 and OKT8 approached normal value . The amount of IgG, IgM, C3 increased abnormally, decreased dramatically after medication, while those of group II and III have not changed significantly . The bacteriostatic test in vitro showed the bacteriostatic effect of RSF-FS on pathogenic B . coli, Shigella dysenteriae and Staphylococcus aureus was the best, that of solution Jian Pi Ling the next, that of SASP was the least effective . Therefore, the principle and method of group I seems to be the best therapeutic programme. J Bacteriol, 1994 Jul, 176(13), 4144 - 56 Structure of the O antigen of Escherichia coli K-12 and the sequence of its rfb gene cluster; Stevenson G et al.; Escherichia coli K-12 has long been known not to produce an O antigen . We recently identified two independent mutations in different lineages of K-12 which had led to loss of O antigen synthesis (D . Liu and P . R . Reeves, Microbiology 140:49-57, 1994) and constructed a strain with all rfb (O antigen) genes intact which synthesized a variant of O antigen O16, giving cross-reaction with anti-O17 antibody . We determined the structure of this O antigen to be -->2)-beta-D-Galf-(1-->6)-alpha-D-Glcp- (1-->3)-alpha-L-Rhap-(1-->3)-alpha-D-GlcpNAc-(1-->, with an O-acetyl group on C-2 of the rhamnose and a side chain alpha-D-Glcp on C-6 of GlcNAc . O antigen synthesis is rfe dependent, and D-GlcpNAc is the first sugar of the biological repeat unit . We sequenced the rfb (O antigen) gene cluster and found 11 open reading frames . Four rhamnose pathway genes are identified by similarity to those of other strains, the rhamnose transferase gene is identified by assay of its product, and the identities of other genes are predicted with various degrees of confidence . We interpret earlier observations on interaction between the rfb region of Escherichia coli K-12 and those of E . coli O4 and E . coli Flexneri . All K-12 rfb genes were of low G+C content for E . coli . The rhamnose pathway genes were similar in sequence to those of (Shigella) Dysenteriae 1 and Flexneri, but the other genes showed distant or no similarity . We suggest that the K-12 gene cluster is a member of a family of rfb gene clusters, including those of Dysenteriae 1 and Flexneri, which evolved outside E . coli and was acquired by lateral gene transfer. J Bacteriol, 1994 Jul, 176(13), 4003 - 10 Genes for TDP-rhamnose synthesis affect the pattern of lipopolysaccharide heterogeneity in Escherichia coli K-12; Klena JD et al.; The rough lipopolysaccharide (LPS) of commonly used strains of Escherichia coli K-12 has two distinctly different band patterns when analyzed by high-resolution polyacrylamide gel electrophoresis . The LPS of ancestral strains such as W1485F- consists primarily of a single broad gel band . In contrast, the LPS of strains derived from strain Y10 such as AB1133 or C600 gives three sharp gel bands . Complementation studies using DNA fragments from the rfb gene cluster of Shigella dysenteriae 1 indicated that the difference between the two gel patterns is due to a mutation in the gene encoding the TDP-rhamnose synthetase, the final enzyme involved in TDP-rhamnose biosynthesis . This mutation arose during the construction of strain Y10, and not in strain 679-680 as previously thought . The requirement for the rfaS gene for synthesis of the broad major band seen in W1485F- LPS and the shift in gel migration of a component of this band when an rfaQ mutation was introduced indicated that this broad band contained the unique form of rough E . coli LPS which has been termed lipooligosaccharide . This finding indicates that lipooligosaccharide is likely to contain rhamnose and suggests a model in which one of the functions of partial substituents such as rhamnose may be to direct core synthesis into different pathways to produce alternative forms of LPS. Lancet, 1994 Jun 4, 343(8910), 1413 - 5 Is protection against shigellosis induced by natural infection with Plesiomonas shigelloides? Sack DA, Hoque AT, Huq A, Etheridge M. Shigellosis due to Shigella sonnei is rare among people growing up and living in developing countries; however, infections due to S sonnei becomes more common than those due to S flexneri as societies develop economically . The relation between risk of S sonnei infection and economic development may be explained by the exposure of developing-country populations to Plesiomonas shigelloides . P shigelloides is often found in surface water, and one serotype (serotype 17) possesses a cell-wall lipopolysaccharide identical to that of S sonnei . Thus, exposure to P shigelloides by drinking contaminated water may immunise populations to S sonnei . As economic development occurs, water quality improves and populations become susceptible to S sonnei . Although drinking water has many advantages, immunisation against S sonnei may be one benefit of traditional water sources. Carbohydr Res, 1994 Jun 2, 259(1), 21 - 34 Synthesis of specifically monofluorinated ligands related to the O-polysaccharide of Shigella dysenteriae type 1; Mulard LA et al.; The synthesis is reported of galactopyranose nucleophiles monofluorinated at positions 3, 4, or 6 and protected by 4,6-O-benzylidene, 3,6-di-O-benzyl, or 3,4-O-isopropylidene groups, respectively . The condensation of these nucleophiles with 2,3,4-tri-O-benzoyl-alpha-L-rhamnosyl bromide gave, after deprotection, the disaccharide analogues of methyl O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-D-galactopyranoside, monofluorinated at position 3, 4, or 6 of the galactoside residue. J Diarrhoeal Dis Res, 1994 Jun, 12(2), 97 - 102 Peripheral blood granulocytes and mononuclear cell responses in monkeys with experimental shigellosis; Islam LN et al.; Changes in neutrophil response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) and the phenotype of peripheral blood mononuclear cells were studied in monkeys after oral challenge with Shigellae . Monkeys were first challenged with S . dysenteriae 1 which caused shigellosis in some of the monkeys . After recovery, the monkeys were rechallenged with S . flexneri 2a . No difference in sensitivity was observed in the monkeys during shigellosis caused by either S . dysenteriae 1 or S . flexneri 2a . The optimal dose of FMLP for neutrophil polarization, a measure of early cell activation, in normal healthy monkeys was 10(-7) M when 67% of the neutrophils were polarized . Neutrophils from monkeys ill with shigellosis required higher doses of FMLP (10(-6) and 5 x 10(-7) M) for maximum polarization . As the monkeys recovered, a gradual decrease in the doses of FMLP for optimal neutrophil polarization was also observed . The percentage of CD2-positive T lymphocytes, the earliest marker for T lymphocytes in the peripheral blood, decreased when the monkeys developed shigellosis and returned to normal levels as the monkeys improved . However, there was no change in the percentage of CD20-positive peripheral blood B lymphocytes. J Diarrhoeal Dis Res, 1994 Jun, 12(2), 121 - 4 Shigellosis in Calcutta during 1990-1992: antibiotic susceptibility pattern and clinical features; Bhattacharya MK et al.; Of 230 cases of bloody diarrhoea studied, 100 (43.5%) were positive for Shigellae by stool culture, of which Shigella dysenteriae type 1 was isolated from 56 cases, S . flexneri from 35, S . boydii from 5 and S . sonnei from 4 . The major clinical manifestations of the patients infected with Shigella spp . were abdominal pain, anorexia, vomiting, tenesmus, and fever . Fever of above 100.5 degrees F and frequency of stool of more than 15 per day were noticed more among cases infected with S . dysenteriae type 1 and S . flexneri . Vomiting was more frequently observed in cases infected with S . sonnei or S . boydii (44.4%) as compared to those infected with S . dysenteriae type 1 (10.7%) and S . flexneri (8.6%) . All Shigella isolates were uniformly susceptible to norfloxacin and ciprofloxacin but were resistant to streptomycin . S . dysenteriae type 1 isolates were susceptible to nalidixic acid (69.6%), ampicillin (5.4%), TMP-SMX (12.5%), furazolidone (98.2%) and gentamycin (80.4%), whereas all other Shigella isolates (S . flexneri, S . boydii, and S . sonnei) were uniformly susceptible to nalidixic acid, > 94% susceptible to furazolidone, and only moderately susceptible to ampicillin (28.6% to 55.5%) and TMP-SMX (22.2% to 48.6%). J Clin Microbiol, 1994 Jun, 32(6), 1427 - 30 Genetic variability and molecular typing of Shigella sonnei strains isolated in Canada; Preston MA et al.; Restriction fragment length polymorphisms (RFLPs) of genomic DNAs from 49 clinical isolates of Shigella sonnei were analyzed by using a modified restriction endonuclease analysis procedure to investigate the genetic variability of this species . After cleavage with the restriction enzyme HaeIII or RsaI, DNA samples were electrophoresed in polyacrylamide gels and the RFLP patterns were visualized by silver staining . The results showed that among 20 strains associated with sporadic cases of infection in three Canadian provinces, 15 distinct RFLP patterns were revealed by HaeIII digestion and 12 distinct patterns were revealed by RsaI digestion . In contrast, the RFLP patterns of individual isolates within six groups of epidemiologically related isolates were identical to each other but distinct from those of unrelated isolates, and these patterns could be used to determine the genetic relationships between isolates associated with separate outbreaks of shigellosis . Our results indicate that the modified restriction endonuclease analysis technique represents a rapid, reproducible, and highly discriminatory method for the molecular typing of this species. Cent Eur J Public Health, 1994 Jun, 2(1), 32 - 6 New serovars of Plesiomonas shigelloides 1992; Aldova E et al.; Fourteen new O (O77-O9O) and 4 new H (H42-H45) antigens were described . Seven O and 2 new H antigens were revealed among strains not agglutinating with antisera against 76 O and 41 H officially recognized serovars . The most frequent was serovar O80:H38 which was isolated in 5 countries (Sweden, Czechoslovakia, Bulgaria, Yugoslavia and Canada) from human material and from sewage and surface water. Zentralbl Bakteriol, 1994 Jun, 281(1), 55 - 60 Typing of Shigella dysenteriae strains of different serogroups by lectins; Mitra A et al.; Ten different serogroups of Shigella dysenteriae were typed with the aid of lectins of known sugar specificity resulting from their interactions with the carbohydrates on lipopolysaccharides in the outer membrane of bacteria as evidenced by the agglutination-inhibition assay with simple carbohydrates . Lipopolysaccharides of two serogroups of Shigella were precipitated with different lectins and the results were corroborated by those derived from the agglutination assay suggesting that Shigella dysenteriae can be characterized on the species level with the aid of lectins. Zentralbl Bakteriol, 1994 Jun, 281(1), 38 - 44 Serovars of Plesiomonas shigelloides; Aldova E; Among 391 P . shigelloides strains, 330 were typable and found to belong to 43 O serovars . The most frequent O serovars were O17 (23%), O32 (7%), O12 (4.5%) and O5, O18 and O44 (3.8% each) . The majority of the serovars represented, with almost 300 strains, were sporadically found in very distant countries of three continents (Europe, Asia, America), whereas only one serovar (O68) was isolated three times in one single district of South Bohemia (Ceske Budejovice) . It suggests that such an incidence of plesiomonads is only seemingly sporadic and that there must be many strains which are not detected owing to the imperfect cultivation methods used so far. Zentralbl Bakteriol, 1994 Jun, 281(1), 24 - 9 Seventy colicin types of Shigella sonnei and an indicator system for their determination; Horak V; An extended scheme of colicin typing of Shigella sonnei strains includes 70 colicin types . Colicin type No . 56 is the producer of a new colicin, for which T marking was proposed . A total number 105 of indicator strains was prepared for typing. Curr Opin Biotechnol, 1994 Jun, 5(3), 312 - 9 Live bacterial vaccines: environmental aspects; Mekalanos JJ; Recombinant DNA technology has greatly accelerated the development of live attenuated bacterial vaccines for cholera, typhoid, and shigellosis . Significant attenuation has been achieved by deleting genes for various virulence determinants, biosynthetic genes, and regulatory genes . As these vaccine candidates move from closed-ward clinical studies to outpatient and field trials, a variety of concerns needs to be addressed about the safety of these vaccines, not only for the vaccinee, but also for the community and the environment . In the case of Vibrio cholerae, specific deletions (delta attRS1 and delta recA) have been introduced into some live vaccine candidates, rendering them incapable of performing homologous and site-specific recombination events that could lead to reacquisition of active cholera toxin genes . Mutations in recA might also limit the persistence of the live vaccine candidate in the environment. Carbohydr Res, 1994 May 20, 258, 105 - 22 Convergent synthesis of an octasaccharide fragment of the O-specific polysaccharide of Shigella dysenteriae type 1; Pozsgay V et al.; A stereocontrolled, convergent synthesis is described of the linear octasaccharide methyl glycoside alpha-L-Rha p-(1-->2)-alpha-D-Gal p-(1-->3)-alpha-Glc p NAc-(1-->3)-al pha-L-Rha p-(1-->3)-alpha-L-Rha p-(1-->2)-alpha-D-Gal p-(1-->3) -alpha-D-Glc p NAc-(1-->3)-alpha-L-Rha p-OMe (11), which corresponds to two contiguous repeating units of the O-specific polysaccharide of Shigella dysenteriae type 1. Carbohydr Res, 1994 May 5, 257(2), 189 - 215 Synthesis and two-dimensional nuclear magnetic resonance analysis of a tetra- and a hexa-saccharide fragment of the O-specific polysaccharide of Shigella dysenteriae type 1; Pozsgay V et al.; The synthesis of the tetra- and hexa-saccharide methyl glycosides alpha-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-alpha-L-Rhap-(1-->3)- alpha-L-Rhap- OMe (1), and alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-D-Galp-(1--> 3)-alpha-D-GlcpNAc- (1-->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-OMe (3) is described, which represent various epitopes of the O-specific polysaccharide of Shigella dysenteriae type 1 . The following monosaccharide intermediates were used: 1,3-di-O-acetyl-2-O-benzoyl-4-O-benzyl-alpha-L-rhamnopyranose (6 alpha), methyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside (7), methyl 2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyranoside (8), 2,3,4-tri-O-benzoyl-alpha-L-rhamnopyranosyl bromide (9), methyl 3,4,6-tri-O-benzyl-2-O-(4-methoxybenzyl)-1-thio-beta-D- galactopyranoside (13), methyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D- galactopyranoside (16), and 2-azido-4,6-O-benzylidene-3-O-bromoacetyl-2-deoxy-beta-D- glucopyranosyl chloride (19) . A detailed analysis of the 1H and 13C NMR spectra of oligosaccharides 1 and 3 confirmed that the hexasaccharide 3 better approaches the conformation of the native polysaccharide, than either 1 or the homologous pentasaccharide 41. J Infect Dis, 1994 May, 169(5), 1035 - 41 Epidemic Shigella dysenteriae type 1 in Burundi: panresistance and implications for prevention; Ries AA et al.; An epidemic of Shigella dysenteriae type 1 infections has affected Africa since 1979 . Reported dysentery cases increase sharply in Burundi during September through December . Of stool samples from 189 patients reporting bloody diarrhea in November 1990, a pathogen was identified in 123 (65%) . The pathogen was S . dysenteriae type 1 in 82 (67%) . All S . dysenteriae type 1 isolates were resistant to ampicillin, chloramphenicol, nalidixic acid, streptomycin, sulfisoxazole, tetracycline, and trimethoprim-sulfamethoxazole . Thirty-two specimens (26%) yielded other Shigella species . Patients with S . dysenteriae type 1 were more likely than those with other Shigella infections to have abdominal pain, "lots of blood" in the stool, blood in the stool specimen examined by the interviewer, recent contact with a person with dysentery, or recent antimicrobial treatment . Thus, the seasonal increase in dysentery was due largely to multidrug-resistant S . dysenteriae type 1, clinical and epidemiologic features may predict such infection, and efforts to control this epidemic must focus on preventing transmission. Voen Med Zh, 1994 May, (5), 4 - 7, 80 {The current problems of preventing acute intestinal infections among the troops}; Borisenko IA et al.; Russian Armed Forces Medical Service has worked out the basic trends of anti-epidemiological measures to be conducted in troops . To battle shigellosis and other acute intestinal infections of non-dysentery etiology a number of factors were taken into account, such as: methods of proliferation of these diseases, dynamics and morbidity rate, etc . The article shows the tasks of medical service during organization and execution of sanitary-epidemiological control over morbidity rate, disclosure of the causes which originate the appearance of acute intestinal infections, elaboration of proposals on the improvement of sanitary-epidemiological situation in troops, strict adherence to the rules of hygiene. Clin Infect Dis, 1994 May, 18(5), 760 - 3 Severe giardiasis in the United States; Lengerich EJ et al.; Giardia lamblia is a common gastrointestinal pathogen but is not generally appreciated as a cause of severe illness . To describe the epidemiology of severe giardiasis, we reviewed data on hospital discharges from the United States and the state of Michigan and compared results for giardiasis with those for shigellosis . From 1979 to 1988, an estimated 4,600 persons were hospitalized for giardiasis annually in the United States; the incidence of giardiasis was 2.0 hospitalizations per 100,000 persons, compared with 2.4 hospitalizations per 100,000 persons for shigellosis . Rates of giardiasis were highest among children younger than 5 years old and women of childbearing age; the median length of hospital stay was 4 days (annual total, 23,238 days) . Among residents of Michigan from 1983 to 1987, the average annual incidence of hospitalization was 1.4 per 100,000 persons for giardiasis, compared with 1.0 per 100,000 persons for shigellosis . Volume depletion was the most frequently listed codiagnosis (33.2%); 18.7% of children younger than 5 years old who had severe giardiasis had failure to thrive . Physicians should consider the diagnosis of giardiasis for persons with severe gastrointestinal illness. Eur J Clin Microbiol Infect Dis, 1994 May, 13(5), 367 - 73 Epidemiology of Shigella infections in two ethnic groups in a geographic region in southern Israel; Finkelman Y et al.; The epidemiology of shigellosis in the Jewish and Bedouin populations that coexist in the same geographic region in southern Israel and share the same medical facilities but live separately under different socioeconomic conditions was examined in a retrospective, culture-based study . The average annual attack rate for the four-year period 1989-1992 was 368/100,000 inhabitants . The average annual attack rate among the Jews, who enjoy Western socioeconomic conditions, was 413/100,000 and the disease showed summer and winter peaks . Shigella sonnei caused 3,336 of 4,560 (73.2%) attacks in this group, and the attack rate of Shigella flexneri decreased during the study period . Among the Bedouins, many of whom live in poverty and overcrowding, a single annual summer peak was observed, the average annual attack rate being 197/100,000 and Shigella flexneri caused 389 of 583 episodes (66.7%) . Resistance to ampicillin or tetracycline was noted in 57% of all Shigella isolates, and 82% were resistant to cotrimoxazole . It is concluded that shigellosis is highly endemic in southern Israel, resistance to antimicrobial drugs is common and living conditions of the population influence the seasonal occurrence of the disease and select for morbidity with specific organisms. J Clin Microbiol, 1994 May, 32(5), 1179 - 83 Characterization of endemic Shigella flexneri strains in Somalia: antimicrobial resistance, plasmid profiles, and serotype correlation; Casalino M et al.; One hundred twelve Shigella flexneri strain isolated from children with diarrheal disease in Somalia in 1983, 1984, 1988, and 1989 were analyzed for serotype, plasmid profile, and genetic location of antimicrobial resistance determinants . The prevalent serotypes were 4 (46% of the isolates), 1b (16%), 2a (16%), 3a (12%), and 6 (8%) . Each serotype was associated with a characteristic predominant plasmid profile, whereas no specific correlation between antimicrobial resistance patterns and single serotypes was found . All but three of the strains were resistant at least to ampicillin, chloramphenicol, spectinomycin, and tetracycline . Of these resistant strains, 41 were resistant to sulfonamide and streptomycin and 14 were resistant to trimethoprim or trimethoprim and kanamycin . The genes for resistance to ampicillin, chloramphenicol, spectinomycin, and tetracycline formed a linkage group located on the chromosome of the strains of all serotypes . The genes for resistance to sulfonamide and streptomycin were located on a 6.3-kb plasmid in strains of serotypes 1b, 2a, and 4 . Conjugative trimethoprim or trimethoprim and kanamycin resistance plasmids with lengths of 80 to 110 kb were present in strains of serotypes 1b, 2a, 3a, and 4 . The systematic presence of a chromosomal component in this uncommon genetic plasmid-chromosome configuration may play a role in the emergence of increased genetic stability of resistance patterns in S . flexneri. West J Med, 1994 May, 160(5), 430 - 3 Moose soup shigellosis in Alaska; Gessner BD et al.; Following a community gathering held in early September 1991, an outbreak of gastroenteritis occurred in Galena, Alaska . We conducted an epidemiologic investigation to determine the cause of the outbreak . A case of gastroenteritis was defined as diarrhea or at least 2 other symptoms of gastrointestinal illness occurring in a Galena resident within a week of the gathering . Control subjects included asymptomatic residents who either resided with an affected person or were contacted by us during a telephone survey . Of 25 case-patients, 23 had attended the gathering compared with 33 of 58 controls . Among persons who attended the gathering and from whom we obtained a food consumption history, 17 of 19 case-patients and 11 of 22 controls ate moose soup . No other foods served at the gathering were associated with illness . Ten case-patients had culture-confirmed Shigella sonnei . Many pots of moose soup were served each day, and persons attended the gathering and ate moose soup on more than 1 day . Moose soup was prepared in private homes, allowed to cool, and usually served the same day . We identified 5 women who had prepared soup for the gathering and in whose homes at least 1 person had a gastrointestinal illness occur at the time of or shortly before soup preparation . This investigation suggests that eating contaminated moose soup at a community gathering led to an outbreak of shigellosis and highlights the risk of eating improperly prepared or stored foods at public gatherings. Vaccine, 1994 May, 12(6), 565 - 8 Outpatient studies of the safety and immunogenicity of an auxotrophic Escherichia coli K-12-Shigella flexneri 2a hybrid vaccine candidate, EcSf2a-2; Taylor DN et al.; A phase II study was conducted in 244 volunteers at Fort Ord, CA, to determine the safety and immunogenicity of EcSf2a-2, a live, oral Shigella vaccine constructed by transfer of genes from Shigella flexneri to Escherichia coli K-12 . In this placebo-controlled study, four doses of vaccine ranging from 2.3 to 9.0 x 10(8) colony-forming units were given on days 0, 3, 14 and 17 . Vaccine shedding occurred from 1 to 3 days after each dose . The vaccine was well tolerated at every dose tested . Significant levels of IgA, IgG or IgM antibody-secreting cells (ASC) recognizing S . flexneri 2a lipopolysaccharide (LPS) were found in 94% of a volunteer subset tested 7 days after the first dose of EcSf2a-2 . Seven days after the third dose, ASC were detected less often (57%), and were mainly IgA . Significant rises in serum antibody to LPS were detected in 37% of vaccine recipients. Vaccine, 1994 May, 12(6), 492 - 8 OmpA-FMDV VP1 fusion proteins: production, cell surface exposure and immune responses to the major antigenic domain of foot-and-mouth disease virus; Ruppert A et al.; Exposure at the bacterial outer surface of the major antigenic epitope of the foot-and-mouth disease (FMDV) viral protein VP1 was studied using protein fusion with outer membrane protein A (OmpA) of Shigella dysenteriae for production and transport of the foreign polypeptide to the outer membrane of Escherichia coli . Fusion constructs with VP1 peptide insertions of up to 56 amino acids in the third outer domain of OmpA could be demonstrated on the bacterial surface by indirect immunofluorescence and immunogold labelling . OmpA fusion proteins with large insertions from sequences of the FMDV protein VP1 were shown to elicit virus-specific immune responses in rabbits. Isr J Med Sci, 1994 May-Jun, 30(5-6), 495 - 7 An update on Shigella vaccines; Ashkenazi S et al.; Recent advances in the understanding of the molecular virulence mechanisms of Shigella have helped to develop a new generation of candidate Shigella vaccines . Approaches that are currently under active study include construction of hybrid Shigella-E . coli strains, performance of attenuating mutations in vitro on natural Shigella strains and acellular, lipopolysaccharide-based vaccines. APMIS, 1994 May, 102(5), 371 - 80 Immunopathological patterns in the rectal mucosa of patients with shigellosis: expression of HLA-DR antigens and T-lymphocyte subsets; Raqib R et al.; Expression of HLA-DR antigens and infiltration of T-lymphocyte subsets (CD4, CD8), cell activation marker (CD25), B cells (CD20), macrophages (CD68 and Ber-Mac 3) and natural killer cells (CD56) in the rectal mucosa of patients with bacillary dysentery and in healthy controls were studied in an effort to interpret the immunopathological changes taking place in the rectal mucosa during the acute phase of shigellosis . The epithelium of the rectal mucosa from 21 of 32 patients was HLA-DR+ . Conventional histology showed acute inflammation in 16 of these patients, chronic inflammation in 3, and in 2 histology was normal . In 7 of 20 controls the epithelium was HLA-DR+; 4 of these 7 were found to suffer from chronic inflammation, whilst in 3 the mucosa was normal . The number of HLA-DR+ intraepithelial lymphocytes in biopsies from patients with Shigella infection was significantly higher (p = 0.005) than in controls . The infiltration of CD8+ cells in the surface epithelium and in the lamina propria, and of CD4+ cells in the lamina propria alone, was significantly higher (p < 0.001) in patients than in controls . The results demonstrate that infiltration of T cells with suppressor/cytotoxic or helper/inducer phenotype in the epithelium and in the lamina propria in Shigella-infected patients may be related to the induction of HLA-DR expression in non-lymphoid cells during acute Shigella infection. Mikrobiol Z, 1994 May-Jun, 56(3), 55 - 9 {The effect of shigellae on delayed hypersensitivity in mice infected by different routes}; Borisov VA et al.; The influence of virulent and avirulent shigellae on delayed hypersensitivity in the case of infection by different methods has been examined . It was found that the stimulating effect of avirulent shigellae and suppressive effect of virulent shigellae were displayed after intranasal infection . Intraperitoneal and intravenous infection was accompanied by only immunosuppressive influence, which was displayed by the virulent bacteria . The discrimination of T-suppressors by low doses of cyclophosphamide did not abolish the suppressive effect of shigellae . At the same time immunosuppressive factor of spleen was produced equally after infection by different-virulence shigellae . A conclusion was drawn that T-suppressors and immunosuppressive spleen factor did not take part in the mechanism of shigellae immunosuppression. Rev Prat, 1994 May 1, 44(9), 1205 - 10 {Hemolytic-uremic syndrome with renal thrombotic microangiopathy}; Kanfer A; Hemolytic-uremic syndrome (HUS) is characterized by intravascular hemolytic anemia with fragmented erythrocytes and thrombocytopenia, acute renal failure, and glomerular/arteriolar fibrin deposition . Most childhood HUS are postdiarrheal (enterocolitic) while adult HUS have various causes, such as shigellosis, pregnancy, malignant hypertension, AIDS, antineoplastic chemotherapy and organ transplantation . Disorders of endothelial hemostatic functions, induced in some cases by bacterial toxins, may have a role in the onset of microthromboses . HUS treatments are both supportive, including antihypertensive drugs and dialysis, and antithrombotic, including plasma infusions or plasma exchanges and antiplatelet agents. J Bacteriol, 1994 Apr, 176(8), 2362 - 73 Nucleotide sequence of the rhamnose biosynthetic operon of Shigella flexneri 2a and role of lipopolysaccharide in virulence; Rajakumar K et al.; N1308, a chromosomal Tn5 mutant of Shigella flexneri 2a, was described previously as a lipopolysaccharide (LPS) mutant with a short O side chain . N1308 formed foci, but not plaques, in LLC-MK2 cell monolayers and was negative in the Sereny test . In this study, the wild-type locus inactivated in N1308 was cloned and further defined by means of complementation analysis . A 4.3-kb BstEII-XhoI fragment of S . flexneri 2a YSH6200 DNA was sufficient to restore both normal LPS and virulence phenotype to the mutant . DNA sequencing of this region revealed four genes, rfbA, rfbB, rfbC, and rfbD, encoding the enzymes required for the biosynthesis of activated rhamnose . The four genes were expressed in Escherichia coli, and the expected protein products were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis . N1308 was shown to have normal levels of surface IpaC and IpaD, while a Western blot (immunoblot) of whole-cell lysates or outer membrane fractions indicated an elevated level of appropriately localized VirG . An in vitro invasion assay revealed that N1308 had normal primary invasive capacity and was able to multiply and move normally within the initial infected cell . However, it exhibited a significant reduction in its ability to spread from cell to cell in the monolayer . A double immunofluorescence assay revealed differences between LLC-MK2 cells infected with the wild-type YSH6000 and those infected with N1308 . The wild-type bacteria elicited the formation of the characteristic F-actin tails, whereas N1308 failed to do so . However, N1308 was capable of inducing deposition of F-actin, which accumulated in a peribacterial fashion with only slight, if any, unipolar accumulation of the cytoskeletal protein. Mol Microbiol, 1994 Apr, 12(2), 267 - 76 Deregulation of temperature-dependent transcription of the invasion regulatory gene, virB, in Shigella by rho mutation; Tobe T et al.; Expression of the virB gene, the transcriptional regulator for the invasion genes encoded by the large plasmid of Shigella flexneri, is temperature-regulated . virB transcription is under the control of VirF and H-NS, which act as positive and negative regulators, respectively, and is highly responsive to changes in DNA superhelicity . To further investigate the molecular mechanisms underlying the thermoregulation of virB transcription, a mutant which expressed an invasion phenotype at both 30 degrees C and 37 degrees C was isolated using miniTn10-kan (miniKAN) random insertion mutagenesis . The insertion site was mapped to the rho gene, and resulted in the addition of 11 amino acids to the C-terminus of the Rho protein . Consequently, decreased transcription termination activity at a rho-dependent terminator, lambda tL1, was observed . In the rho mutant, both the transcription of virB and expression of invasion genes were activated at 30 degrees C and were less responsive to changes in temperature . The deregulation of virB expression by the mutation was dependent upon the virB promoter, since the effects of the mutation on virB transcription were abolished when its promoter region was replaced by the tac promoter . Temperature-responsive changes in DNA topology, as determined by linking numbers of a reporter plasmid, showed that changes in DNA superhelicity in the rho mutant were smaller than that in the wild type . Furthermore, when the mutant was grown in medium containing novobiocin, an inhibitor of DNA gyrase, virB transcription at 30 degrees C as well as at 37 degrees C was greatly diminished . These results indicated that Rho protein could have a profound effect on topological temperature-dependent changes in DNA structure, thus contributing to thermoregulation of virB transcription. Scand J Gastroenterol, 1994 Apr, 29(4), 313 - 7 Comparison of pivmecillinam and nalidixic acid in the treatment of acute shigellosis in children; Alam AN et al.; The efficacy of oral pivmecillinam was compared with nalidixic acid in the treatment of acute shigellosis in children 1-8 years of age . In a double-blind trial we studied 80 comparable children with bloody diarrhoea of less than 3 days' duration . Shigella spp . was isolated in 71 children . Patients were randomly assigned to receive either pivmecillinam, 50 mg/kg.day, or nalidixic acid, 60 mg/kg.day, both given orally for 5 days . The stool frequency decreased progressively in both treatment groups . Nalidixic acid failed to eradicate Shigella species in 10 patients, compared with three in the pivmecillinam group (p = 0.04) . Similarly, clinical failure was observed in 11 of 37 patients receiving nalidixic acid and in 2 of 26 patients infected with nalidixic acid-susceptible strains as against none in the group receiving pivmecillinam . The results suggest that pivmecillinam given orally was, in fact, more effective than nalidixic acid in the treatment of acute shigellosis in children, particularly when the resistant strains are taken into account. J Clin Microbiol, 1994 Apr, 32(4), 1092 - 4 Epidemic spread of Shigella sonnei shigellosis and evidence for development of immunity among children attending day-care centers in a communal settlement (Kibbutz); Lerman Y et al.; An investigation of two Shigella sonnei shigellosis outbreaks that occurred in a communal settlement indicated that the transmission of the pathogen was restricted to day-care classes and secondary infection of family members was minimal . Development of serotype-specific immunity following S . sonnei infection was observed among infected children. Ann Intern Med, 1994 Mar 15, 120(6), 500 - 5 Household epidemiology of Cryptosporidium parvum infection in an urban community in northeast Brazil; Newman RD et al.; OBJECTIVE: To examine the transmission of Cryptosporidium infection in households with an identified person with cryptosporidiosis . DESIGN: Prospective cohort study . SETTING: An urban slum in Fortaleza, Brazil . PARTICIPANTS: Thirty-one households with a child less than 3 years of age (index case) who was positive for Cryptosporidium parvum using acid-fast and auramine-stained stool smears . MEASUREMENTS: Three stool samples (at 0, 2, and 6 weeks after identification of the index case) and two serum samples (0 and 6 weeks) were collected from each family member in households with an index case of Cryptosporidium infection . RESULTS: Forty-five percent of index cases of Cryptosporidium infection were associated with persistent (> 14 days) diarrhea . Secondary cases of Cryptosporidium infection were identified either by stool examination or seroconversion in 18 (58%) of 31 households involving 30 persons, yielding an overall transmission rate of 19% . Of the 202 persons in this study with at least one serum sample available for analysis, 191 (94.6%) had evidence of antibodies (either IgM or IgG) to Cryptosporidium . CONCLUSIONS: Cryptosporidium parvum is highly transmissible and infective in the family setting, with transmission rates similar to other highly infectious enteric pathogens such as Shigella species . These data are cause for added concern because of the rapidly increasing rate of seropositivity for human immunodeficiency virusPIP: Between December 1990 and April 1992 investigators enrolled 31 households with a less than 3-year-old child infected with Cryptosporidium parvum in a prospective cohort study to determine the infectivity of Cryptosporidium parvum in families living in crowded conditions, mainly in the Goncalves Dias slum in Fortaleza, Brazil . The median household size was 7 . The median age of the 33 index cases was 11 months, while the median age of the 192 family contacts was 21 years . 94% of the index cases had diarrhea at the time Cryptosporidium infection was diagnosed . 45% of the index cases had persistent diarrhea ( 14 days) . The median duration of diarrhea was 14 days (range, 1-84 days) . Most index cases (83%) had at least 1 other positive stool test for Cryptosporidium . Just 1 index case shed oocysts for 6 weeks . Index cases transmitted Cryptosporidium infection to 30 (19%) of 182 household contacts as evidenced by either a positive stool examination or seroconversion . These 30 secondary cases were from 18 of the 31 households . Only 8 (27%) secondary cases had diarrhea and 25% of them had persistent diarrhea, suggesting preexisting protective immunity in this area where Cryptosporidium infection is endemic . Household contacts who were 5 years old or younger were significantly more likely to have been diagnosed with Cryptosporidium than were those older than 5 years (30% vs . 5%; p 0.001) . Most persons with at least 1 serum sample available for analysis (191/202 = 94.6%) had antibodies (IgM or IgG) to Cryptosporidium . The high rate of transmission of Cryptosporidium in this population, the serious threat of persistent diarrhea among young children, and the ever increasing rate of HIV transmission in Brazil (especially among slum dwellers with no access to condoms and to education about AIDS) should raise great concern . Cell, 1994 Mar 11, 76(5), 829 - 39 Cadherin expression is required for the spread of Shigella flexneri between epithelial cells; Sansonetti PJ et al.; Shigella flexneri, a gram-negative pathogen, invades the human colonic epithelium . After entering epithelial cells, bacteria escape into the cytoplasm, move intracellularly, and pass from cell to cell . The bacterium diverts actin and associated actin-binding proteins to generate a cytoskeleton-based motor that pushes forward the bacterium . As the moving bacterium reaches the inner face of the host-cell cytoplasmic membrane, a protrusion forms that allows passage of this bacterium into a neighboring cell . We show here that components of the intermediate junction are used by the bacterium to allow this passage . Using S180, a mouse fibroblastic sarcoma cell line that does not produce cell adhesion molecules (CAM), and S180L and S180cadN, the same cell line transfected with L-CAM and N-cadherin cDNA, respectively, we demonstrate that expression of a cadherin is required for cell-to-cell spread to occur. J Clin Microbiol, 1994 Mar, 32(3), 835 - 8 Comparative virulence of blood and stool isolates of Shigella sonnei; Seymour C et al.; Shigellemia is rare in developed countries and might result from the emergence of unusually virulent strains . We compared systemic invasiveness markers of isolates from the blood of 3 temporally clustered patients with Shigella sonnei bacteremia in Boston with those of 11 unrelated contemporaneous strains from stools of people in New England . We found no difference between the two groups in O-chain length by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mouse 50% lethal dose, in vivo response to iron, and susceptibility to serum, which varied from moderately susceptible to ultrasusceptible . Mean intraperitoneal 50% lethal doses of smooth form I colonies for mice were equally low (10(5.8) CFU) in both groups, and the 50% lethal doses were lowered equally further in the two groups by predosing with iron to levels useful in mouse model sepsis studies . S . sonnei bacteremia may reflect compromised host defenses, not bacterial virulence. J Infect Dis, 1994 Mar, 169(3), 538 - 46 Pathogenesis of Shigella diarrhea: XVII . A mammalian cell membrane glycolipid, Gb3, is required but not sufficient to confer sensitivity to Shiga toxin; Jacewicz MS et al.; Shiga toxin recognizes a galactose-alpha 1-->4-galactose terminal glycolipid, globotriaosylceramide (Gb3), in sensitive mammalian cells and is translocated by endocytosis to the cytoplasm, where it blocks protein synthesis . To determine if Gb3 is both required and sufficient for toxicity, Gb3 content in cells was altered by blocking key biosynthetic or degradative path enzymes with specific inhibitors . The resulting decrease or increase in cellular Gb3 was associated with a decrease or increase in binding of and response to Shiga toxin . Toxin-resistant Gb3-deficient variants of sensitive cells fused with liposomes containing Gb3 but not globotetraosylceramide (Gb4) became susceptible, whereas fusion of Gb3 liposomes to naturally resistant Gb3-deficient CHO cells increased toxin binding but not cytotoxicity . These data demonstrate that Gb3 is required, but not sufficient, for the action of Shiga toxin and suggest the existence of a toxin translocation mechanism linked to surface glycolipids that is not expressed in CHO cells. Infect Immun, 1994 Mar, 62(3), 956 - 60 Cytotoxicity of a shiga toxin A subunit-CD4 fusion protein to human immunodeficiency virus-infected cells; al-Jaufy AY et al.; Shiga toxin (STX) is a ribosome-inactivating cytotoxin produced by Shigella dysenteriae serotype 1 . The enzymatic domain of the STX A polypeptide has been defined by introducing amino- and carboxy-terminal deletions in the polypeptide and assessing activity in a cell-free translation system . Three recombinant forms of StxA which possess enzymatic activity were genetically fused to a 165-amino-acid polypeptide derived from CD4, the cellular receptor for human immunodeficiency virus type 1 (HIV-1) . This strategy eliminated the STX receptor-binding subunit and directed the hybrid toxins to cells expressing the HIV-1 surface glycoprotein gp120 . A bacterial lysate containing these toxin chimeras killed the HIV-1-infected T-cell line 8E5 but was not cytotoxic toward the uninfected parental cell line A3.01 . This cytotoxic activity was specifically inhibited by monoclonal antibodies which block the interaction between CD4 and gp120 . These StxA-CD4 hybrids add to the repertoire of recombinant fusion proteins which possess the capacity to selectively kill HIV-1-infected T cells. Trans R Soc Trop Med Hyg, 1994 Mar-Apr, 88(2), 144 - 6 Approaches to vector control: new and trusted . 4 . Appropriate technology for vector control: impregnated bed nets, polystyrene beads and fly traps; Curtis CF; There are social, economic and entomological problems with conventional insecticidal spraying methods for vector control . There is therefore interest