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KMID : 0364820140500030185
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Korean Journal of Microbiology
2014 Volume.50 No. 3 p.185 ~ p.190
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Prevalence and Molecular Characterization of Quinolone Antibiotic Resistance in Escherichia coli Isolates from Raw Bulk Milk in Gyeonggi-do
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Kang So-Won
Lee Sang-Jin
Choi Sung-Sook
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Abstract
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The aim of this study was to investigate the prevalence of quinolone resistant E. coli from raw bulk milk and to
characterize the resistance determinants. In this study, the gyrA, gyrB, parC, and parE quinolone resistance
determining regions (QRDR) were sequenced from quinolone resistant E. coli isolates. Also, the presence of
plasmid-mediated quinolone resistance (PMQR) and the expression of efflux pump genes based on quantitative
real-time PCR (qRT-PCR) were investigated. Of the 487 coliform bacteria, 9 strains showed nalidixic acid
resistance, and 6 of the 9 nalidixic acid resistant isolates were also ciprofloxacin resistant. These 9 strains had a
single mutation at codon 83 (S83L) in gyrA, 2 of them had double mutations at codon 83 and 87 (S83L and D87N)
in gyrA and 3 of the 9 isolates had single mutations at codon 80 (S80I) in parC. None of the 9 isolates harbored
PMQR determinants. Compared with wild-type E. coli ATCC 25922, an over-expression of the acrB gene (2.15?5.74
fold), encoding the pump component of the AcrAB-TolC efflux pump was observed in 4 of 6 ciprofloxacin resistant
isolates. This study identified the quinolone resistance mechanism of E. coli isolated from raw milk samples in
Gyeonggi-do.
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KEYWORD
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acrB, E. coli, PMQR, QRDR, quinolone resistance, raw milk samples
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