转座子tnpU基因在多重耐药革兰阴性杆菌中的分布情况

目的 研究转座子tnpU基因和β-内酰胺酶在多重耐药革兰阴性杆菌中的分布情况.方法 用纸片扩散初筛试验、扩散确证试验进行超广谱β-内酰胺酶(ESBLs)表型检查,头孢西丁三维试验进行AmpC β-内酰胺酶的表型检查,纸片协同试验筛选产金属β-内酰胺酶(MBL)菌株；用多重聚合酶链反应(PCR)技术扩增转座子tnpU基因,并进行DNA测序；用MIC药敏法分析多重耐药革兰阴性杆菌的药物敏感性.结果 转座子tnpU的总检出率为25.5％,在各菌种的检出率分别为大肠埃希菌占6.3％(3株)、肺炎克雷伯菌占8.3％(1株)、鲍曼不动杆菌占33.3％(20株)、铜绿假单胞菌占43.2％(16株)；β-内酰胺酶表型检测中,ESBLs的检出率最高,转座子tnpU基因阳性的菌株大多数β-内酰胺酶表型为阳性；转座子tnpU基因阳性菌株对抗生素的耐药率显著高于转座子阴性菌株(P＜0.05).结论 转座子tnpU基因在非发酵菌中的分布较广泛,可能在多重耐药机制中起重要作用.

Distribution of transposon tnpU in multi-drug resistant gram-negative bacilli

Objective To investigate the distribution of transposon tnpU and beta-lactamases in multi-drug resistant gram-negative bacilli.Methods Extended spectrum beta-lactamases(ESBLs) were tested by disc diffusion screen test,which were further ascertained by disc diffusion confirmatory test.AmpC beta-lactamases were tested by cefoxitin threedimension test.Metallo-beta-lactamase(MBL) was tested by double-disc synergy test.Transposon tnpU was amplified by polymerase chain reaction(PCR),and PCR products were sequenced subsequently.Antibiotics susceptibility of multidrug resistant gram-negative bacilli was detected by MIC susceptibility method.Results The total positive rate of transposon tnpU was 25.5%.tnpU was found in 3 isolates of Escherichia coli(6.3%),1 isolate of Klebsiella pneumoniae(8.3%),20 isolates of Acinetobater baumannii(33.3%),and 16 isolates of Pseudomonas aeruginosa(43.2%).The positive rate of ESBLs in beta-lactamases phenotypical test was the highest,which the strains of carrying transposon tnpU were almost positive in beta-lactamases phenotypical test.The tnpU positive strains had higher level of resistance than negative one(P<0.05).Conclusion Transposon tnpU was widely occurred in non-fermentative bacteria and may play an important role in multiple drug resistance.