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B．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 three- dimension 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 multi- drug 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-laetamases 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.