CONICET | Buscador de Institutos y Recursos Humanos

Shiga toxin-producing Escherichia coli (STEC) can produce haemorrhagic colitis and haemolytic uremic syndrome (HUS) mainly after consumption of contaminated food of bovine origin. The O157:H7 serotype is frequently implicated in clinical manifestations, but non-O157 serotypes can also be associated with human infections. Although the antimicrobial therapy is not recommended, the study of antimicrobial susceptibility of STEC strains has epidemiological relevance. This study was aimed to determine the serotype and antimicrobial susceptibility of one STEC strain isolated from 52 cooked sausages (1.9%, 1/52) and three STEC strains isolated from 58 fresh sausages (1.7%, 1/58) in San Luis, Argentina, between August 2012 and July 2013. The research of the serotype O157 and flagellar H7 antigen by PCR directed to amplify rfbEO157 and fliCh7 genes separately, as well as the antimicrobial susceptibility test by the disk diffusion method on Mueller Hinton agar were performed in our laboratory. The assessment of non-O157 serotypes, the stx2 subtype and the clonal relatedness.between strains were performed at the Physiopathogeny Service, National Institute of Infectious Diseases ?Dr. C. G. Malbrán?, Buenos Aires. The strain of cooked sausage was identified as STEC ONT:H7 whereas two strains of fresh sausage were serotypified as STEC O112:H19, and the remaining one was ONT:HNT (NT: not typeable). Strains belonged to stx2c genotype and were susceptible to chloramphenicol and ofloxacin. In our country, non-O157 STEC serotypes are involved in more than 30-40% HUS cases. STEC O112 has been previously identified in cattle from Argentina, so its presence in manufactured by-products of bovine origin is possible. However, no reports of O112 involved in STEC outbreaks or sporadic cases in humans have been found.