Qnr Prevalence of Plasmid-Mediated Quionlone Resistance

Abstract

Objective: To explore distribution of qnrA,qnrB,qnrS genes in gram-negative bacteria isolates in Renmin Hospital of Wuhan University. Methods: qnr genes in nonrepetitive 129 iaolates of E.coli and 13 isolates of E.cloacac and 37 isolates of K. pneunoniae were detected by PCR. Susceptibility test to 15 antibiotics were also performed by K-B in virto. MICs of ciprofloxacin were determined by agar dilution technique. Plasmid conjugatable test was applied to examine whether qnr gene located in conjugatable plasmid or not. IntI were detected by PCR. Results: Among 179 gram negative bacteria isolates, the qnrA genes were present in 3.88% of E.coli and 7.69% of E.cloaca. The qnrB genes were present in 6.20% of E.coli and 7.69% of E.cloaca. The qnrS genes were present in 2.33% of E.coli and 18.92% of K. pneumoniae. All positive isolates were suspectible to imipenem but resistance to some other drugs. 2 qnrA positive isolates and 4 qnrB positive isolates of were susceptible to ciprofloxacin. Qnr gene were on transferable plasmids and could be dsseminated by clone. 23 of them were I type integron-positive isolates. Conclusions: In HuBei province, the prevalence of qnr is comfirmed and we find qnr genes could also be in quinolone suspectible strains. So it is necessary to study the prevalence and mechanism of qnr genes of quinolones resistance further in the future.