临床分离黏质沙雷菌染色体及质粒介导的喹诺酮类耐药机制研究  

Chromosome and plasmid-mediated quinolone resistance mechanism in clinical isolates of Serratia marcescens

作　　者：杨海飞[1] 周雪[1] 程君[1] 胡立芬[1] 朱玉林[1] 叶英[1] 李家斌[1] 

机构地区：[1]安徽医科大学第一附属医院感染科,合肥230022

出　　处：《中华检验医学杂志》2012年第8期706-710,共5页Chinese Journal of Laboratory Medicine

摘　　要：目的了解安徽地区临床分离株黏质沙雷菌质粒介导喹诺酮类耐药基因的流行情况以及gyrA、parC基因变异对抗菌药物的耐药性产生的影响。方法采用琼脂稀释法测定2005至2010年34家医院收集的104株黏质沙雷菌的MIC；采用PCR检测其中31株耐环丙沙星的黏质沙雷菌的qnr、aac（6’）-Ib、qepA基因以及gyrA和parC基因，对阳性扩增产物进行测序分析；对qnr、aac（6’）-Ib．cr阳性菌株做转移接合试验，PCR扩增并测序确定接合子的基因型，测定供体菌、受体菌和接合子对喹诺酮类及其他类型抗菌药物的MIC。结果共检出31株环丙沙星耐药的黏质沙雷菌，共6株携带qnr基因和（或）aac（6’）．Ib-cr基因，其中2株携带qnrB6亚型，1株携带qnrS2亚型，4株携带aac（6’）-Ib-cr基因（其中1株同时携带qnr基因）。9株检测出gyrA基因突变，7株检测出parC基因突变。6株携带qnr基因和（或）aac（6’）-Ib-cr基因的菌株中有5株转移接合成功。接合子与受体菌相比，对喹诺酮类的MIC值均有不同程度的提高。结论染色体及质粒介导的耐药基因在临床分离的黏质沙雷菌对喹诺酮类药物耐药中起重要的作用，且可以水平传播，故应引起高度重视。Objective To investigate the prevalence of plasmid-mediated quinolone resistance （PMQR） determinants [ qnr, aac （6＇）-Ib-cr and qepA] and mutations in quinolone resistance-determining regions （QRDRs） of gyrA and parC and their association with flnoroquinolone susceptibility in clinical isolates of Serratia marcescens in Anhui. Methods The minimum inhibition concentration （ MIC ） of 104 strains of S. marcescens collected from various clinical specimens from 34 hospitals during 2005 to 2010 were determined by agar dilution method. The qnr, aac（6＇）-Ib, qepA, gyrA and parC genes were screened by polymerase chain reaction （PCR） in 31 strains resistant to ciprofloxacin, and positive results were subsequently confirmed by sequencing. The conjugation experiments were performed for qnr and aac （6＇）-Ib- er positive strains. The MIC of S. marcescens isolates, recipient strains and conjugants were tested by agar dilution method for quinolones and other antimicrobial agents. Results Six strains of the 31 S. marcescens isolates harboured qnr and/or aac （6＇）-Ib-cr genes. Among those 6 strains, 2 strains harboured a qnrB6 gene, 1 harboured a qnrS2 gene, and 4 harboured aac（6＇）-Ib-cr, whereas no qnrA-, qnrC- or qnrD-positive isolate was detected. None of the 31 isolates carried the qepA gene. Mutations in the QRDR of gyrA and parC genes were detected in 9 and 7 isolates, respectively. The conjugation experiments were successfully carried out in 5 isolates of 6 PMQR determinants-postive strains. The MIC of conjugants for quinolones were increased evidently compared to recipient strains. Conclusions Chromosome and plasmid-mediated resistance determinants play an important role in quinolone resistance in clinical isolates of S. marcescens. And more important is that the PMQR determinants can be horizontal transmitted. It is necessary to continuously survey and watch for the spread of PMQR in S. marcescens in public health control program.

关 键 词：沙雷菌 黏质 喹诺酮类 染色体 质粒 抗药性 细菌 

分 类 号：R440[医药卫生—诊断学]