Isolation of Shiga toxigenic Escherichia coli from butcheries in Taquaritinga city, State of São Paulo, Brazil

Shiga toxigenic Escherichia coli (STEC) has been implicated as the cause of several human diseases. Samples (ground beef, grinding-machines and human hands) from 23 butcheries were assayed for E. coli using standard microbiological methods, and 287 isolates were submitted to polymerase chain reaction for the detection of stx 1, stx 2 and eae genes. Four STEC isolates were recovered, two from ground beef and two from grinding-machines; all harbored the stx 2 gene and were negative for the eae gene. All E. coli isolates including the four STEC were screened for antibiotic resistance. High levels of resistance against several antimicrobial agents were detected; those most commonly observed were to tetracycline (76.6%), amoxicillin (64.1%) and cephalothin (58.8%). Such high levels of antimicrobial resistance highlight the need for a more rational use of these agents in cattle.