AUTHOR=Liu Xiaoqiang , Liu Haixia , Wang Le , Peng Qian , Li Yinqian , Zhou Hongchao , Li Qinfan 

TITLE=Molecular Characterization of Extended-Spectrum β-Lactamase-Producing Multidrug Resistant Escherichia coli From Swine in Northwest China

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01756

DOI=10.3389/fmicb.2018.01756

ISSN=1664-302X

ABSTRACT=<p><bold>Objectives:</bold> The aim of the present study was to explore the prevalence and molecular characterization of extended-spectrum β-lactamase (ESBL)-producing <italic>Escherichia coli</italic> collected from pig farms in Northwest China.</p><p><bold>Methods:</bold> Between May 2015 and June 2017, a total of 456 <italic>E. coli</italic> isolates were collected from fecal samples of healthy and diarrheal pigs in Northwest China to screen the ESBL producers. The β-lactamases, plasmid-mediated quinolone resistance (PMQR) genes and virulence genes among ESBL producers were corroborated by PCR and sequencing. Finally, ESBL producers were further grouped according to phylogenetic background and genetic relatedness.</p><p><bold>Results:</bold> Forty-four (9.6%) out of the 456 <italic>E. coli</italic> isolates were identified as ESBL-producing isolates. All ESBL producers exhibited multidrug resistance (MDR) phenotype, and more than 90% of the ESBL producers were resistant to amoxicillin, amoxicillin-clavulanic acid, oxytetracycline, enrofloxacin and sulfamethoxazole/trimethoprim. All ESBL producers harbored at least one type of β-lactamase, with <italic>bla</italic><sub>CTX−M</sub>, <italic>bla</italic><sub>TEM</sub>, <italic>bla</italic><sub>SHV</sub>, <italic>bla</italic><sub>OXA−48</sub>, and <italic>bla</italic><sub>KPC−2</sub> being detected in forty, thirty, seven, four, two and one isolates, respectively. Sequencing revealed the most common <italic>bla</italic><sub>CTX−M</sub> subtype was <italic>bla</italic><sub>CTX−M−14</sub> (<italic>n</italic> = 24), followed by <italic>bla</italic><sub>CTX−M−15</sub> (<italic>n</italic> = 14), <italic>bla</italic><sub>CTX−M−64</sub> (<italic>n</italic> = 11), <italic>bla</italic><sub>CTX−M−9</sub> (<italic>n</italic> = 10) and <italic>bla</italic><sub>CTX−M−123</sub> (<italic>n</italic> = 9). <italic>qnrS</italic> (<italic>n</italic> = 23) was the predominant PMQR gene, and all PMQR genes were detected in co-existence with β-lactamase genes. <italic>estA</italic> (<italic>n</italic> = 18) and F4 (<italic>n</italic> = 18) were the most prevalent enterotoxin and fimbrial adhesin, respectively, and 27 different virotypes were found with respect to the association of enterotoxins and fimbrial adhesins. Twenty-four different sequence types (STs) were identified among 44 ESBL producers, and clones ST405, ST10 and ST648 were strongly present in more than one-third (34.1%) of ESBL producers.</p><p><bold>Conclusion:</bold> All ESBL-producing <italic>E. coli</italic> isolates exhibited MDR phenotype, and showed high prevalence of β-lactamase and PMQR genes. Especially, one isolate harbored ESBL genes <italic>bla</italic><sub>TEM</sub>, <italic>bla</italic><sub>SHV</sub>, <italic>bla</italic><sub>CTX−M−9</sub>, <italic>bla</italic><sub>CTX−M−14</sub>, <italic>bla</italic><sub>CTX−M−64</sub>, and carbapenemase gene <italic>bla</italic><sub>OXA−48</sub> and <italic>bla</italic><sub>KPC−2</sub>, as well as PMQR genes <italic>qnrS, qnrB, qnrD, qepA</italic> and <italic>aac(6')-Ib-cr</italic>.</p>