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ABSTRACTThe complex relation between the genotype of Helicobacter pyloriand its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain virulence factors (vacAs1, vacAm1, and cagA) are associated with duodenal ulcer disease. However, the H. pylorigenotype is known to vary with geographic region. In the present study, we compared several virulence markers (cagA, vacA, and iceA) and neutral markers (IS605, IS606, and IS608) in H. pyloristrains isolated from 65 adult patients with peptic ulcer (PU) and 50 patients with nonulcer dyspepsia (NUD). PCR tests indicated that cagAis present in 75% of the strains from patients with PU compared to 55% in patients with NUD, and 80% of the isolates from patients with PU carried potentially toxigenic vacAs1alleles of the vacuolating cytotoxin gene (vacA) compared to 60% in isolates from patients with NUD. However, no significant difference in any other virulence marker was observed in isolates from both groups. Phylogenetic analysis of the vacAmiddle region and the 5' end of the cagAgene indicates that Bangladeshi isolates are more closely related to H. pyloriisolates from India and are different from isolates from East Asia.

ABSTRACTPeriodic monitoring of antimicrobial susceptibility of Neisseria gonorrhoeaeis essential for early detection of emergence of drug resistance. A total of 343 gonococcal strains isolated from high-risk and general populations in Bangladesh from 1997 to 1999 were studied. The MICs of penicillin, tetracycline, ciprofloxacin, ceftriaxone, and spectinomycin for the isolates were determined by the agar dilution method. Of the isolates from 1997, 9% were resistant (MIC = 1.0 µg/ml) to ciprofloxacin, while 41 and 49% of the isolates from 1998 and 1999, respectively, were resistant to ciprofloxacin. Of the N. gonorrhoeaeisolates from 1998 and 1999, 1.2 and 3.6%, respectively, both were penicillinase producing and displayed plasmid-mediated tetracycline resistance.

ABSTRACTAeromonads are causative agents of a number of human infections. Even though aeromonads have been isolated from patients suffering from diarrhea, their etiological role in gastroenteritis is unclear. In spite of a number of virulence factors produced byAeromonasspecies, their association with diarrhea has not been clearly linked. Recently, we have characterized a heat-labile cytotonic enterotoxin (Alt), a heat-stable cytotonic enterotoxin (Ast), and a cytotoxic enterotoxin (Act) from a diarrheal isolate ofAeromonas hydrophila. Alt and Ast are novel enterotoxins which are not related to cholera toxin; Act is aerolysin related and has hemolytic, cytotoxic, and enterotoxic activities. We studied the distribution of the alt, ast, andactenterotoxin genes in 115 of 125 aeromonads isolated from 1,735 children with diarrhea, in all 27 aeromonads isolated from 830 control children (P= 7 × 10-4for comparison of rates of isolation of aeromonads from cases versus those from controls), and in 120 randomly selected aeromonads from different components of surface water in Bangladesh.Aeromonasisolates which were positive only for the presence of the altgene had similar distributions in the three sources; the number of isolates positive only for the presence of the astgene was significantly higher for the environmental samples than for samples from diarrheal children; and isolates positive only for the presence of the actgene were not found in any of the three sources. Importantly, the number of isolates positive for both the altand astgenes was significantly higher for diarrheal children than for control children and the environment. Thus, this is the first study to indicate that the products of both the altand astgenes may synergistically act to induce severe diarrhea. In 26 patients,Aeromonasspp. were isolated as the sole enteropathogen. Analysis of clinical data from 11 of these patients suggested that isolates positive for both the altand astgenes were associated with watery diarrhea but that isolates positive only for the altgene were associated with loose stools. Most of the isolates from the three sources could be classified into seven phenospecies and eight hybridization groups. For the first time,Aeromonas eucrenophilawas isolated from two children, one with diarrhea and another without diarrhea.

ABSTRACTCommercial sex workers (CSWs) serve as the most important reservoir of sexually transmitted diseases (STD), including gonorrhea. Periodic monitoring of the antimicrobial susceptibility profile ofNeisseria gonorrhoeaein a high-risk population provides essential clues regarding the rapidly changing pattern of antimicrobial susceptibilities. A study concerning the prevalence of gonococcal infection among CSWs was conducted in Bangladesh. The isolates were examined with regards to their antimicrobial susceptibility to, and the MICs of, penicillin, tetracycline, ciprofloxacin, cefuroxime, ceftriaxone, and spectinomycin by disk diffusion and agar dilution methods. The total plasmid profile of the isolates was also analyzed. Of the 224 CSWs, 94 (42%) were culture positive for N. gonorrhoeae. There was a good correlation between the results of the disk diffusion and agar dilution methods. Some 66% of the isolates were resistant to penicillin, and 34% were moderately susceptible to penicillin. Among the resistant isolates, 23.4% were penicillinase-producing N. gonorrhoeae(PPNG). 60.6% of the isolates were resistant and 38.3% were moderately susceptible to tetracycline, 17.5% were tetracycline-resistant N. gonorrhoeae, 11.7% were resistant and 26.6% had reduced susceptibility to ciprofloxacin, 2.1% were resistant and 11.7% had reduced susceptibility to cefuroxime, and 1% were resistant to ceftriaxone. All PPNG isolates contained a 3.2-MDa African type of plasmid, and a 24.2-MDa conjugative plasmid was present in 34.1% of the isolates. Since quinolones such as ciprofloxacin are recommended as the first line of therapy for gonorrhea, the emergence of significant resistance to ciprofloxacin will limit the usefulness of this drug for treatment of gonorrhea in Bangladesh.

ABSTRACTAntimicrobial susceptibility of 120 Helicobacter pyloriisolates to metronidazole, tetracycline, clarithromycin, and amoxicillin was determined, and 77.5, 15, 10, and 6.6% of the isolates, respectively, were resistant. Only rdxAinactivation and both rdxAand frxAinactivation were responsible for metronidazole resistance in 66% (8 of 12) and 33% (4 of 12) of the isolates, respectively.