Detection, isolation and characterization of Shiga toxin-producing Escherichia coli (STEC) in fresh ground beef from butcher shops in Concepción, Tucumán Province

Abstract

Shiga toxin-producing Escherichia coli is an emerging foodborne pathogen. There are many STEC serotypes associated with human diseases, being the O157:H7 serotype the most prevalent. Ground beef is the main transmission vehicle. In Concepción city, Tucumán Province, between September and December 2004, two hemolytic uremic syndrome (HUS) cases were diagnosed. The main objective of this work was to detect, isolate and characterize STEC O157 and non-O157 strains in fresh ground beef. Between September and December 2004, 53 fresh ground beef samples were collected from butcher shops in Concepción city. The USDA-FSIS (2002) methodology was used for detection, isolation and characterization of STEC O157:H7. Two PCR techniques for E. coli non-O157 detection and a previous intra-laboratory validated methodology for the isolation and characterization of these strains were used. The stx2 gen was identified in seven samples and the rfbO157 gene also in four of them. However, only one E. coli O157:H7 strain, biotype C, carrying the eae, stx2 and ehxA genes, was isolated. The present study shows the importance of implementing techniques for the detection of this emerging pathogen in meat samples.