Published in Scientific Works. Series C. Veterinary Medicine, Vol. LXI
Written by Laurenţiu Mihai CIUPESCU, Isabela Madalina NICORESCU, Iuliana MIHAI, Rodica DUMITRACHE, Rodica TANASUICA
STEC are very important as emergent food-borne pathogens, being implicated in large outbreaks as well as in sporadic cases of hemorrhagic colitis and haemolytic uraemic syndrome (HUS). Following the largest HUS outbreak reported in Europe in May 2011 (3255 confirmed cases and 33 deaths), in Romania was performed during 2012 a study for detection and identification of Shiga toxin/Verotoxin-producing Escherichia coli (STEC/VTEC) from food of animal origin. According ISO 13136/2011, an E coli strain is considered STEC if its genome contains simultaneously both stx (stx1 and/or stx2) and eae genes. STEC are widespread in animals but ruminants are thought to be their natural reservoir. Taking into account the high prevalence of STEC in the gastrointestinal tract of ruminants and the possibility to contaminate the meat during the slaughter process, there were investigated carcass swabs and meat subsequently processed. The techniques used included both molecular and microbiological methods. The molecular methods applied was based on the detection by real- time PCR of the major virulence genes of STEC, stx1, stx2 and eae, and as well of the serogroup associated genes O157, O145, O111, O103 and O26 from bacterial enrichment broths and subsequent isolated colonies. From 445 samples tested in this study, the STEC isolation was not achieved, but single and combinations of the target virulence genes stx1, stx2 and eae were detected in 128 samples. The presence of the major toxigenic genes in 28.76 % of the samples infer that the probable origin of target genes that we detected by PCR could be the free-Stx phages from outside bacteria cells that can be present in food samples. Knowing from literature that the Stx phages can propagate in E. coli becoming potentially able to transduce stx genes indicates that STEC food-borne outbreaks can occur anytime.
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