Nanobiophotonics

Shiga toxin-producing Escherichia coli (STEC) strains are an emerging zoon otic pathogen, associated with foodborne outbreaks. STEC can cause acute diarrhea, bloody diarrhea and/or hemolytic uremic syndrome (HUS), affecting mostly children under 5 years of age and the elderly. We aimed to determine the presence of STEC in national and imported vacuum packaged beef sold in Chilean supermarkets. Between May and December 2012, we analyzed 304 meat samples from 32 supermarkets of which 87 (28.6%)were national and 217 (71.4%) imported. A total of 20 samples (6.6%) were STEC positive by PCR, 3/87 (3.4%) and 17/217(7.8%) national and imported, respectively. Toxigenic profiles of 20 STEC strains were: stx1/stx2 (7/20), stx1 (2/20), stx2 (11/20) and shiga toxin variants profiles were stx1a,(14) stx2a,(12) stx2b,(1) stx2c (11) and stx2d.(5). Additional virulence genes were also detected including iha (12/20), hlyA (13/20) and saa (13/20).Identifiable serogroups were O113 (6/20), O174 (2/20), O141 (1/20), O8 (1/20) and 10STEC strains non typable. In conclusion, near 7% of vacuum packaged beef products sold in supermarkets located in Santiago, Chile were contaminated with STEC strains harboring virulence genes and serogroups previously associated with clinical cases of bloody diarrhea and HUS. Appropriate sanitary measures must be implemented to improve STEC control in the agri-food chain and thus reduce the risk of HUS in children and the elderly.