耐碳青霉烯类鲍曼不动杆菌6种基因及ISAbal插入序列的研究

Research on six genes and insertion sequence ISAbal of carbopenems-resistant Acinetobacter baumannii

目的研究耐碳青霉烯类鲍曼不动杆菌(CRAB)的基因型特点和与插入序列ISAbal的关系,探讨其耐药机制。方法收集CRAB 70株(非重复)和碳青霉烯类敏感鲍曼不动杆菌10株,采用2-巯基丙酸抑制试验检测金属β-内酰胺酶(MBLs);采用多重聚合酶链反应(PCR)扩增blaIMP、blaVIM、blaOXA-23、blaOXA-24、blaOXA-51、blaOXA-58、ISAbalOXA-23,扩增产物DNA测序进行比对。结果 70株CRAB 2-巯基丙酸与头孢他啶协同试验全部为阴性(即MBLs阴性),用7对特异性引物对70株CRAB和10株敏感菌进行PCR扩增,所有CRAB均携带blaOXA-23、blaOXA-51,未检出blaOXA-24;1株含有blaOXA-58;80株均不携带blaIMP和blaVIM;插入序列ISAbalOXA-2370株CRAB均有表达,敏感菌均不表达。结论 CRAB的主要耐药基因是blaOXA-51和blaOXA-23;另外,blaOXA-23上游都存在插入序列ISAbal。鲍曼不动杆菌的耐药性与MBLs、blaOXA-24、blaOXA-58无相关性。

Objective To study the relationship between the genotype characteristics and insertion sequence lSAbal of carbopenems-resistant Acinetobacter baumannii（ CRAB）, and investigate the drug-resistant mechanism. Methods A total of 70 strains of CRAB （no repeat strains） and 10 strains of carbopenems-sensitive Acinetobacter baumannii were collected. Metalloenzyme beta-lactamase （MBLs） were detected by 2-mereaptopropionic acid inhibition test. The blaIMP, blaVIM, blaoxA-23, blaoxA-24, blaoxA-51, blaoxA-58 and ISAbaloxA-23 were amplified by multiplex polymerase chain reaction （PCR）. The amplified products were measured for DNA sequence. Results The synergy tests were negative （MBLs negative ） by 2-mereaptopropionie acid and ceftazime in 70 strains of CRAB. Through 7 pairs of specific primers, 70 strains of CRAB and 10 strains of carbopenems-sensitive Acinetobacter baumannii were determined for PCR amplification. All the CRAB strains carried blaoxA-23 and blaoxA-51, but blaoxA-24 was never detected. Only 1 strain carried blaoxA.58, and the 80 strains did not carry blaiMP and blawM. In addition, all the CRAB strains carried insertion sequence ISAbaloxA-23, however, all the sensitive strains did not carry. Conclusions Major genes are blaoxA-51 and blaoxA-23 in the CRAB strains. Insertion sequence ISAbal is located in the upstream of blaoxA-23. There is no correlation among drug-resistance of Acinetobacter baumannii to MBLs, blaoxA-24 and blaoxA-58.