Prevalence and Genetic Characterization of Shiga Toxin-Producing Escherichia coli Isolates from Slaughtered Animals in Bangladesh

• Published in: Applied and Environmental Microbiology 2008-09, Vol.74 (17), p.5414-5421
• Main Authors: Islam, Mohammad A, Mondol, Abdus S, de Boer, Enne, Beumer, Rijkelt R, Zwietering, Marcel H, Talukder, Kaisar A, Heuvelink, Annet E
• Format: Article
• Language: English
• Subjects: Abattoirs; Animals; Bacteriophage Typing; Bangladesh - epidemiology; beef-cattle; Biological and medical sciences; Buffaloes - microbiology; Cattle - microbiology; Cattle Diseases - epidemiology; Cattle Diseases - microbiology; dairy-cattle; Disease Reservoirs - microbiology; DNA, Bacterial - genetics; E coli; Electrophoresis, Gel, Pulsed-Field; Escherichia coli; Escherichia coli Infections - epidemiology; Escherichia coli Infections - microbiology; Escherichia coli Infections - veterinary; Feces - microbiology; Food Microbiology; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genetics; Goat Diseases - epidemiology; Goat Diseases - microbiology; Goats - microbiology; hemolytic-uremic syndrome; infections; intimin types; large plasmid; Meat - microbiology; Microbiology; o157-h7; Prevalence; Proteins; serotypes; Serotyping; Shiga Toxin 1 - genetics; Shiga Toxin 2 - genetics; Shiga-Toxigenic Escherichia coli - classification; Shiga-Toxigenic Escherichia coli - genetics; Shiga-Toxigenic Escherichia coli - isolation & purification; strains; Toxins; Virulence Factors - genetics; virulence genes
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.00854-08

To determine the prevalence of Shiga toxin (Stx)-producing Escherichia coli (STEC) in slaughter animals in Dhaka, Bangladesh, we collected rectal contents immediately after animals were slaughtered. Of the samples collected from buffalo (n = 174), cows (n = 139), and goats (n = 110), 82.2%, 72.7%, and 11.8% tested positive for stx₁ and/or stx₂, respectively. STEC could be isolated from 37.9%, 20.1%, and 10.0% of the buffalo, cows, and goats, respectively. STEC O157 samples were isolated from 14.4% of the buffalo, 7.2% of the cows, and 9.1% of the goats. More than 93% (n = 42) of the STEC O157 isolates were positive for the stx₂, eae, katP, etpD, and enterohemorrhagic E. coli hly (hlyEHEC) virulence genes. STEC O157 isolates were characterized by seven recognized phage types, of which types 14 (24.4%) and 31 (24.4%) were predominant. Subtyping of the 45 STEC O157 isolates by pulsed-field gel electrophoresis showed 37 distinct restriction patterns, suggesting a heterogeneous clonal diversity. In addition to STEC O157, 71 STEC non-O157 strains were isolated from 60 stx-positive samples from 23.6% of the buffalo, 12.9% of the cows, and 0.9% of the goats. The STEC non-O157 isolates belonged to 36 different O groups and 52 O:H serotypes. Unlike STEC O157, most of the STEC non-O157 isolates (78.9%) were positive for stx₁. Only 7.0% (n = 5) of the isolates were positive for hlyEHEC, and none was positive for eae, katP, and etpD. None of the isolates was positive for the iha, toxB, and efa1 putative adhesion genes. However, 35.2% (n = 25), 11.3% (n = 8), 12.7% (n = 9), and 12.7% (n = 9) of the isolates were positive for the lpfO₁₁₃, saa, lpfAO₁₅₇/₀₁₋₁₄₁, and lpfAO₁₅₇/OI₋₁₅₄ genes, respectively. The results of this study provide the first evidence that slaughtered animals like buffalo, cows, and goats in Bangladesh are reservoirs for STEC, including the potentially virulent STEC strain O157.