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Resistance Mechanism of Carbapenem-Resistant Enterobacteriaceae to Quinolones by Ming Wei, Na Tu, Kai Yang

Background: To investigate the epidemics of plasmid-mediated quinolone resistance (PMQR) gene in carbapenem-resistant Enterobacteriaceae (CRE) and the resistance mechanism.
Methods: We collected CRE bacteria isolated clinically between December 2017 and December 2018 for identification and drug sensitivity testing using a VITEK2 Compact Analyzer. Furthermore, genes, including qnrA, qnrB, qnrS, qepA, and acc (6’) Ib-cr, were determined through the polymerase chain reaction and sequencing. The hori-zontal transfer of PMQR gene was validated through the plasmid conjugational test.
Results: Drug resistance rate of carbapenem-resistant Escherichia coli against quinolones was 100%, while the rate of carbapenem-resistant Klebsiella pneumoniae ranged from 15.56% to 33.33%. The detection rate of acc (6’) Ib-cr was the highest (87.72%), followed by qnrB (77.19%) and qnrS (17.54%). Additionally, there were two bacteria carrying the qnrA gene (3.51%), but qepA gene was not isolated from the samples. In total, 84.21% of these bacteria carried 2 or 3 kinds of PMQR genes. Among 8 bacteria with successful plasmid conjugation, PMQR gene transfer was detected in all of them, but with no significant change in the minimum inhibitory concentration of quinolones.
Conclusions: CRE remain sensitive to quinolones in spite of the high detection rate of PMQR gene in this hospital.

DOI: 10.7754/Clin.Lab.2020.200220