title: The occurrence of atypical enteropathogenic Escherichia coli strains among children with diarrhea in Iran.
abstract: The aim of this study was to investigate the genetic diversity and class 2 integron content of typical and atypical enteropathogenic Escherichia coli (EPEC) strains isolated from children less than 5 years of age. Biochemical tests and serogrouping were performed for identification of isolated strains, and each isolate was tested for susceptibility to 7 antimicrobial agents. The identity of EPEC and their class 2 integron content was confirmed by PCR analysis and sequencing. Subtyping of Escherichia coli spp. was performed through pulsed-field gel electrophoresis (PFGE) analysis. All EPEC strains were resistant to 6 antimicrobial agents except for gentamycin. The most prevalent serogroups among EPEC strains were found to be members of O86 and O127 serogroups (37.7 %) and O44, O125, and O128 (42.8 %). The majority of our EPEC isolates (60.7 %) were identified as atypical. Among the total 28 isolates, 4 (14.2 %) harbored a class 2 integron 1,500 or 2,300 bp in size, corresponding to dfrA1-sat1 and dfrA1-sat1-aadA1 resistance gene cassette arrays, respectively. PFGE analysis showed an extensive diversity among the isolates. No PFGE clustering was observed according to bundle-forming pilus (bfp) bacteria, suggesting that PFGE analysis could not discriminate between typical and atypical EPEC strains. The high ratio of antibiotic-resistant strains and the large heterogeneity among EPEC isolates with low prevalence of class 2 integrons signify the need to examine for other mechanism(s) involved in conferring resistance in typical and atypical populations of EPEC.
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Jalal-Ale-Ahmad Ave, 14117-13116, Tehran, Iran. b.bakhshi@modares.ac.ir
authors.forename: Bita
authors.initials: B
authors.lastname: Bakhshi
authors.forename: Soheil
authors.initials: S
authors.lastname: Fallahzad
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Pourshafie
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D054308:Enteropathogenic Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D005798:Genes, Bacterial; D006801:Humans; D032023:Integrons; D007492:Iran / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D010802:Phylogeny
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial