基因qnr与大肠埃希菌和肺炎克雷伯菌耐药水平的相关性研究

Comparison Study of qnr in Clinical Isolates of Both Escherichia Coli and Klebsiella Pneumoniae

目的研究耐药基因qnr（qnrA，qnrB和qnrS）在大肠埃希菌和肺炎克雷伯菌环丙沙星敏感株与耐药株中与ESBLs阳性株和阴性株中的分布状况和比较分析。方法从2006年全国美平耐药监测网点中收集241株非重复的大肠埃希菌（122株）和肺炎克雷伯菌（119株），用琼脂对倍稀释法测定所有菌株对药物环丙沙星、头孢他啶、头孢他啶／克拉维酸、头孢噻肟、头孢噻肟／克拉维酸的MIC值。采用PCR检测所有菌株的质粒介导喹诺翻耐药基因qnr。结果在241株筛选出的大肠埃希菌和肺炎克雷伯菌中，环丙沙星的敏感率为36．9％，耐药率为61．4％。头孢噻肟的敏感率为45．2％，耐药率为39．0％。头孢他啶的敏感率为74．3％，耐药率为19．9％。ESBLs阳性株占56．8％。qnr共检出46株，总阳性率为19．1％（46／241）。其中qnrA有2株（0．8％，2／241），qnrB有25株（10．4％，25／241），qnrS有19株（7．9％，19／241）。一株从痰标本分离的肺炎克雷伯菌同时检出qnrB和qnrS。在肺炎克雷伯菌中，qnr共栓出39株，阳性率为32．8％（39／119）；在大肠埃希菌中，qnr共检出6株，阳性率为4．9％（6／122）。在环丙沙星敏感菌株中，qnr基因的阳性率为13．5％（12／89）；在环丙沙星耐药菌株中，qnr基因的阳性率为21．6％（32／148）。经酽检验，qnr基因在环丙沙星敏感菌株与耐药菌株检出率的差异无统计学意义（X^2=2．435，P〉0．05）。在ESBLs阳性的菌株中，qnr的阳性率为23．4％（32／137）；在ESBLs阴性菌株中，qnr的阳性率为12．5％（13／104）。经Z。检验，qnr基因在ESBLs阳性株与ESBLs阴性株中检出率的差异具有统计学意义（X^2=4．590，P〈0．05）。结论质粒介导喹诺酮类耐药基因qnr在大肠埃希菌和肺炎克雷伯菌中分布广泛。qnr基因与环丙沙星的耐药水平没有相关性，而与细菌是否产ESBLs有相关性。

Objective To investigate the prevalence of pasmid-mediated quinolone resistance gene qnr （qnrA,qnrB and qnrS） in the clinical isolates of Escherichia coli and Klebsiella pneumoniae in China. Methods All non-repetitive 241 clinical isolates with Escherichia coli（122 isolates） and Klebsiella pneumoniae （119 isolates） collected drawn from the Chinese Meropenem Susceptibility Surveillance study collection in 2006. The MIC of ciprofloxacin and other antibacterial agents were determined by agar dilution. Qnr gene were detected by PCR. The isolates were divided into two groups according to the resistence level of ciprofloxacin and producing ESBLs or non-producing ESBLs. Results Qnr was present in 19. 1% （46/241） of isolates, and among these, 2 isolates carried qnrA （0.8 %,2/241 ）, 25 isolates carried qnrB （10.4 %, 25/241 ）, 19 isolates carried qnrS （7.9 %, 19/241） and 1 Klebsiella pneurnoniae isolate from sputum carried qnrB and qnrS. Qnr was present in 32. 8% （39/119） of Klebsiella pneumoniae isolates and 4.9% （6/122） of Escherichia cdi isolates. There was no significant difference between the two groups （the susceptibility and resistance for ciprofloxacin） in the prevalence of isolates carrying the qnr genes （13.5% and 21.6% ,X^2=2. 435 ,P〉0. 05）. There was significant difference between the two groups （producing ESBLs and non-producing ESBLs） in the prevalence of isolates carrying the qnr genes（23.4% and 12.5% ,X^2= 4. 590,P〈0. 05）. Conclusion The plasmid-mediated qnr existed in the Escherichia coli and Klebsiella pneumoniae strains in China. And there was no significant difference between the two groups （the susceptibility and resistance for ciprofloxacin） in the prevalence of isolates carrying the qnr genes,and there was significant difference between the two groups（producing ESBLs and non-producing ESBLs） in the prevalence of isolates carrying the qnr genes.