Molecular Characterization of Shiga Toxin-Producing Escherichia coli Isolated from the Environment of a Dairy Farm

POLIFRONI, R.; ETCHEVERRÍA, A. I.; SANZ, M.E.; CEPEDA, R. E.; KRÜGER, A.; LUCCHESI, P. M. A.; FERNÁNDEZ, D.; PARMA A. E.; PADOLA, N. L.

CURRENT MICROBIOLOGY

SPRINGER

Lugar: Berlin; Año: 2012 vol. 65 p. 337 - 343

0343-8651

Environmental samples were taken fromground, cattle water troughs, and feeders from a dairy farmwith different STEC prevalence between animal categories(weaning calves, rearing calves, and dairy cows). Overall,23 % of samples were positive for stx genes, stx2 being themost prevalent type. Isolates were analyzed by PCRmonoplex to confirm generic E. coli and by two multiplexPCR to investigate the presence of stx1, stx2, eae, saa,ehxA, and other putative virulence genes encoded in STECplasmids: katP, espP, subA, and stcE. The toxin genes weresubtyped and the strains were serotyped. The ground andthe environment of the rearing calves were the sites withthe highest number of STEC-positive samples; however,cattle water troughs and the environment of cows were theplaces with the greater chance of finding stx2EDL933 whichis a subtype associated with serious disease in humans.Several non-O157 STEC serotypes were detected. Theserotypes O8:H19; O26:H11; O26:H-; O118:H2; O141:H-;and O145:H- have been asociated with human illness.Furthermore, the emergent pathogen STEC O157:H- (stx1?ehxA?eae) was detected in the environment of the weaningcalves. These results emphasize the risk that represents theenvironment as source of STEC, a potential pathogen forhuman and suggest the importance of developing controlmethods designed to prevent contaminations of foodproducts and transmission from animal to person.