铜绿假单胞菌对喹诺酮类药物耐药的分子机制研究

Study on the molecular resistant mechanisms to quinolones in clinical isolates of Pseudomonas aeruginosa

目的:研究铜绿假单胞菌对喹诺酮类药物耐药的分子机制,为临床抗感染治疗提供依据。方法:用PCR法检测染色体介导的喹诺酮类耐药基因gyrA、gyrB、parC、parE和质粒介导的喹诺酮类耐药基因qn-rA、qnrB、qnrC、qnrD、qnrS、qepA、aac(6')-Ib-cr、oqxA和oqxB,并对gyrA和parC阳性结果进行测序分析。结果:98株耐环丙沙星的铜绿假单胞菌中未检出parE、qnrC和qnrS基因。gyrA、gyrB和parC的阳性率分别为96.9%、87.8%和75.5%。测序证实84株菌(85.7%)发生gyrA或parC基因突变。90株菌(91.8%)携带质粒介导的耐药基因,qnrA、qnrB、qnrD、qepA、aac(6')-Ib-cr、oqxA和oqxB的阳性率分别为31.6%、86.7%、15.3%、11.2%、53.1%、8.2%和26.5%,其中qnrB和aac(6')-Ib-cr具有高携带率。结论:染色体介导的喹诺酮类耐药基因突变以及质粒携带qnr、qepA、aac(6')-Ib-cr和oqxAB耐药基因是铜绿假单胞菌耐喹诺酮类药物的主要机制。首次在铜绿假单胞菌中发现qnrB基因和qnrD基因。

Objective：To study the molecular resistant mechanism of Pseudomonas aeruginosa to quinolones antibiotics and provide basis for clinical anti-infection therapy.Methods：The chromosome mediated-quinolones resistant genes gyrA,gyrB,parC,parE and plasmid-mediated resistant genes qnrA,qnrB,qnrC,qnrD,qnrS,qepA,oqxA,oqxB and aac（6′）-Ib-cr were determinated by PCR.DNA sequencing was used for identification of gyrA and parC.Results：In 98 isolates of Pseudomonas aeruginosa resistant to ciprofloxacin,parE,qnrC and qnrS were not detected.The positive rates of gyrA,gyrB,parC,qnrA,qnrB,qnrD,qepA,aac（6′）-Ib-cr,oqxA and oqxB were 96.9%,87.8%,75.5%,31.6%,86.7%,15.3%,11.2%,53.1%,8.2% and 26.5%,respectively.By sequence analysis,84 strains（85.7%） had gyrA or parC mutation.90 strains（91.8%） contained plasmid-mediated resistant genes,among them the positive rate of qnrB and aac（6′）-Ib-cr were higher than other genes.Conclusion：Chromosome-mediated gene mutation as well as plasmid-mediated qnr,qepA,oqxAB and aac（6′）-Ib-cr may be the main mechanisms of Pseudomonas aeruginos resisitance to quinolones.qnrB and qnrD were found in Pseudomonas aeruginosa the first time.