Objective To study the relationship between the genotype characteristics and insertion sequence ISAbal 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-mercaptopropionic acid inhibition test. The blaIMP,blaVIM,blaOXA-23,blaOXA-24,blaOXA-51,blaOXA-58 and ISA balOXA-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-mercaptopropionic 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 blaVIM 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.%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-23 70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.
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