Abstract
BackgroundAs a primary source of Shiga-toxin-producing Escherichia coli (STEC) infection, cattle are often targeted to develop strategies for reducing STEC contamination. Monitoring the virulence potentials of STEC isolates from cattle is important for tracing contamination sources, managing outbreaks or sporadic cases, and reducing the risks for human infection. This study aimed to investigate the prevalence of STEC in cattle farm samples in South Korea and to assess their virulence potentials.ResultsIn total, 63 STEC were isolated from 496 cattle farm samples, and temperature and rainfall affected STEC prevalence (p < 0.001). The O157 serogroup was most prevalent, followed by O108, O8, O84, O15, and O119. In the stx variant test, high prevalence of stx2a and stx2c (known to be associated with high STEC virulence) were observed, and stx2g, a bovine STEC variant, was detected in STEC O15 and O109. Additionally, stx1c was detected in eae-positive STEC, suggesting genetic dynamics among the virulence genes in the STEC isolates. STEC non-O157 strains were resistant to tetracycline (17.9%), ampicillin (14.3%), and cefotaxime (3.6%), while STEC O157 was susceptible to all tested antimicrobials, except cefotaxime. The antimicrobial resistance genes, blaTEM (17.5%), tetB (6.3%), and tetC (4.8%), were only detected in STEC non-O157, whereas tetE (54.0%) was detected in STEC O157. AmpC was detected in all STEC isolates. Clustering was performed based on the virulence gene profiles, which grouped STEC O84, O108, O111, and O157 together as potentially pathogenic STEC strains. Finally, PFGE suggested the presence of a prototype STEC that continues to evolve by genetic mutation and causes within- and between-farm transmission within the Gyeonggi province.ConclusionsConsiderable numbers of STEC non-O157 were isolated from cattle farms, and the virulence and antimicrobial resistance features were different between the STEC O157 and non-O157 strains. STEC from cattle with virulence or antimicrobial resistance genes might represent a threat to public health and therefore, continual surveillance of both STEC O157 and non-O157 would be beneficial for controlling and preventing STEC-related illness.
Highlights
As a primary source of Shiga-toxin-producing Escherichia coli (STEC) infection, cattle are often targeted to develop strategies for reducing STEC contamination
This study investigated the prevalence of STEC O157 and non-O157 in cattle farm samples in South Korea and assessed the virulence potentials of STEC isolates from these samples by characterizing stx variants, antimicrobial resistance, and virulence genes
STEC prevalence in cattle farms Of 496 samples collected from 29 visits to 15 farms, 63 STEC were isolated from 17 visits to seven farms (Table 2)
Summary
As a primary source of Shiga-toxin-producing Escherichia coli (STEC) infection, cattle are often targeted to develop strategies for reducing STEC contamination. Monitoring the virulence potentials of STEC isolates from cat‐ tle is important for tracing contamination sources, managing outbreaks or sporadic cases, and reducing the risks for human infection. Since the identification of STEC O157:H7 as a foodborne zoonotic disease in 1982 [1], human infections by STEC have been reported worldwide [2, 3]. While numerous studies have focused on STEC O157:H7, the most wellknown and notorious serotype, >400 serotypes of STEC non-O157 have been implicated as etiological agents of several outbreaks and in sporadic cases of STEC infection [4]. Predicting the risk of STEC is especially important for public health because STEC infection might develop into a life-threatening disease, and is often associated with large and multinational outbreaks [10, 12, 13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
