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目的了解武汉大学人民医院分离的革兰阴性杆菌中qnr基因及其所携带的广谱β-内酰胺酶(ESBLs)基因的流行情况。方法采用聚合酶链反应(PCR)方法对129株大肠埃希菌、29株肺炎克雷伯菌和10株阴沟肠杆菌进行qnr基因检测。对qnr阳性株,检测Ⅰ类整合酶基因及SHV-1、TEM-1、CTX.M、OXA-Ⅰ、OXA-Ⅱ、OXA-Ⅲ、DHA、EBC型ESBLs基因。KB纸片法检测对16种抗菌药物的体外抗菌活性,美国临床实验标准委员会表型筛选和确证试验检测产ESBLs株。质粒接合试验分析qnr基因的水平转移能力,ERIC-PCR进行DNA同源性分析。结果6株菌株检出qnr基因(5株大肠埃希菌和1株阴沟肠杆菌),肺炎克雷伯菌中未检出;6株菌仅对亚胺培南全部敏感且对多种抗生素耐药,Ⅰ类整合酶基因扩增全为阳性,其中有2株大肠埃希菌对环丙沙星敏感。4株菌携带TEM-1型ESBLs基因、1株菌携带OXA-Ⅲ型ESBLs基因、2株菌携带EBC型AmpC酶;每株菌至少携带2种以上ESBLs基因。qnr基因介导的喹诺酮类耐药具有水平转移性,DNA同源性分析有2株指纹图谱一致。结论武汉地区存在qnr基因的流行。qnr阳性株多重耐药严重,且携带多种ESBLs基因。
Objective To investigate the prevalence of qnr gene and its extended-spectrum β-lactamase (ESBLs) gene in gram-negative bacilli isolated from People’s Hospital of Wuhan University. Methods 129 strains of Escherichia coli, 29 strains of Klebsiella pneumoniae and 10 strains of Enterobacter cloacae were tested for qnr by polymerase chain reaction (PCR). The integrase genes of type Ⅰ and the ESBLs genes of SHV-1, TEM-1, CTX.M, OXA-Ⅰ, OXA-Ⅱ, OXA-Ⅲ, DHA and EBC were detected for qnr positive strains. Antibacterial activity of 16 antimicrobial agents in vitro was detected by KB disk method. ESBLs strain was detected by phenotypic screening and confirmatory test from American Clinical Laboratory Standards Committee. Plasmid junctions were used to analyze the level of qnr gene transfer and ERIC-PCR to analyze DNA homology. Results The qnr gene (5 strains of Escherichia coli and 1 strain of Enterobacter cloacae) was detected in 6 strains of bacteria and not detected in Klebsiella pneumoniae. All 6 strains were sensitive to imipenem and resistant to various antibiotics Medicine, type Ⅰ integrase gene amplification were all positive, of which 2 strains of Escherichia coli sensitive to ciprofloxacin. Four strains carried TEM-1 type ESBLs genes, one strain carrying OXA-Ⅲ type ESBLs genes and two strains carrying EBC type AmpC enzymes. Each strain carried at least two ESBLs genes. Quinolone resistance mediated by qnr gene has horizontal metastasis, and two fingerprints of DNA homology analysis are consistent. Conclusion There is a prevalence of qnr gene in Wuhan. qnr positive multi-drug resistant strains, and carry a variety of ESBLs genes.