Prevalence and characteristics of Shiga toxin-producing Escherichia coli (STEC) from cattle in South Korea between 2010 and 2011

Abstract

A total of 156 Shiga-like toxin producing Escherichia coli (STEC) were isolated from fecal samples of Korean native (100/568, 18%) and Holstein dairy cattle (56/524, 11%) in South Korea between September 2010 and July 2011. A total of 33% (52 isolates) of STEC harboring both of stx1and stx2, and genes encoding enterohemolysin (ehxA) and autoagglutinating adhesion (saa) were detected by polymerase chain reaction in 83 (53%) and 65 (42%) isolates, respectively. By serotyping, 6 STEC strains from native cattle and 4 STEC strains from dairy cattle were identified as O26, O111, O104 and O157 which were O-serotypes involved in human disease. MLST and PFGE patterns revealed a various genetic diversity of the STEC strains and genetic differences between years. Antimicrobial susceptibility tests showed that the multidrug resistance rate was increased from 12% in 2010 to 42% in 2011. Difference between isolates of 2010 and 2011 is suggested to be resulted from seasonal variations during sampling or large-scale slaughtering in South Korea to control foot and mouth disease outbreak occurred in early 2011 but continuous epidemiologic studies will be needed. More public health attention has to be required for dairy products as the risk of STEC, especially in dairy cattle, seem to be increased in this study.