Investigation and Characterization of Escherichia coli 045, 0103, 0111 and 0145 from Raw Meats, Hat-Yai City, Thailand

Abstract

Non-0157 Shiga toxin-producing Escherichia coli (STEC) are gradually become a major public health concern worldwide. One of the STEC potential vehicles carrying them to humans are raw meats. Thus, this current study investigates the STEC in an important serogroup, O45, 0103, 0111 and 0145, from raw meats in southern Thailand by immunomagnetic separation technique (IMS). The prevalence of E. coli 045, 0103, 0111 and 0145 were found to be 12.4%, 42%, 0%, and 3%, respectively. Most of them were not members of STEC including other five diarrheagenic E. coli (DEC) pathotypes except serogroup 0145 that belonged to atypical enteropathogenic E. coli (aEPEC) and one 0103 strain (strain 103.10) from chicken that identified to be extraintestinal pathogenic E. coli (ExPEC). Investigation of other virulence genes exhibited that fimH, responsible for bacterial adherence, was the gene that found in all strains in all serogroups while asta encoding for EAST-1 toxin was found in 045 and 0103 as 63.2% and 20.8%, respectively. In addition, Ipf encoding long polar fimbriae was found in 045 and 0145 as 30.6% and 100%, respectively. Phylogenetic group analysis demonstrated that the majority of E. coli 045 belonged to group D (88%) followed by group A (8%) and B1 (4%) but none belonged to group B2. Contrary, E. coli O103 showed that 3%, 5%, 30% and 62% of strains belonged to group B2, D, B1 and A, respectively. While all E. coli O145 isolates belonged to phylogenetic group D. Intactness of stx2 phage integration sites revealed that in O45 and 0103, sbcB was occupied by some prophages in highest rate, followed by Z2577. No prophage integration was detected in all E. coli O145. Antimicrobial susceptibility assay of 045 and 0103 showed the high proportion of resistance to cephalothin (78% and 78%), streptomycin (51% and 93%), cotrimoxazole (39% and 28%), tetracycline (31% and 48%) and chloramphenical (23% and 33%), respectively. Furthermore, multi-drug resistant ability was found in 49% and 59.2% of 045 and O103, respectively. DNA typing of E. coli 045 and 0103 surrogates by BOX-PCR analyzed at 80% genetic similarity exhibited 5 and 22 distinct clusters. Interestingly, in each serogroup, some strains from different samples and different time intervals demonstrated the identical fingerprint, suggesting that they are genetically closely related or they may be originated from the same bacterial clones. Keywords: Escherichia coli 045, Escherichia coli O103, Escherichia coli O111, Escherichia coli O145, atypical enteropathogenic Escherichia coli, raw meat, southern Thailand