AUTHOR=Xu Guofeng , An Wei , Wang Hongdong , Zhang Xiuying 

TITLE=Prevalence and characteristics of extended-spectrum β-lactamase genes in Escherichia coli isolated from piglets with post-weaning diarrhea in Heilongjiang province, China

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01103

DOI=10.3389/fmicb.2015.01103

ISSN=1664-302X

ABSTRACT=<p><bold>Objectives:</bold> The purpose of this study was to investigate the prevalence of extended spectrum β-lactamase (ESBL) genes in <italic>Escherichia coli</italic> isolated from post-weaning diarrhea (PWD) piglets in Heilongjiang province, China.</p><p><bold>Methods:</bold> Of 458 <italic>E. coli</italic> isolated from 589 fecal samples from PWD piglets, a total of 198 isolates were confirmed as ESBL producers by the double-disk synergy test (DDST). Polymerase chain reaction (PCR) and sequencing were performed to identify genes for ESBL, plasmid-mediated quinolone resistance (PMQR), and integrons.</p><p><bold>Results:</bold> Of the 198 isolates, <italic>bla</italic><sub>CTX−M</sub> and <italic>bla</italic><sub>TEM</sub> were detected in 191 and 149 isolates, respectively. Sequencing revealed that 10 <italic>bla</italic><sub>CTX−M</sub> subtypes were detected, and <italic>bla</italic><sub>CTX−M−14</sub> was the most prevalent, followed by <italic>bla</italic><sub>CTX−M−55</sub> and <italic>bla</italic><sub>CTX−M−65</sub>. Of the 149 TEM-positive strains, four were <italic>bla</italic><sub>TEM−52</sub> and the rest were <italic>bla</italic><sub>TEM−1</sub>. Among the 198 ESBL-positive isolates, 173 isolates were found to harbor at least one PMQR gene, with <italic>oqxAB, qnrS, qnrB, qepA</italic>, and <italic>aac(6</italic>′<italic>)-Ib-cr</italic> being detected alone or in combination in 125, 114, 26, 24, and 45 strains, respectively. One hundred and fifty-five ESBL-positive isolates were also positive for class I integron (<italic>int1</italic>), and eight different gene cassette arrays were confirmed in 110 isolates by restriction fragment length polymorphism (RFLP) and DNA sequencing analyses, with predominance of <italic>dfrA17</italic>-<italic>aadA5, dfrA12</italic>-<italic>orfF</italic>-<italic>aadA2</italic>, and <italic>dfrA1</italic>-<italic>aadA1</italic> arrays.</p><p><bold>Conclusion:</bold> To the best of our knowledge, this is the first report of the <italic>bla</italic><sub>TEM−52</sub> gene in pig <italic>E. coli</italic> isolates in China and this is also the first description of the coexistence of the <italic>qnrB, qnrS, aac(6</italic>′<italic>)-Ib-cr, qepA</italic>, and <italic>oqxAB</italic> genes in one <italic>E. coli</italic> strain.</p>