耐亚胺培南鲍曼不动杆菌碳青霉烯酶基因型及插入序列ISAba1研究

Carbapenemase genotype and insertion sequence ISAba1among imipenem-resistant Acinetobacter baumannii isolates

目的检测耐亚胺培南鲍曼不动杆菌的碳青霉烯酶基因型及其基因周围环境。方法对101株耐亚胺培南鲍曼不动杆菌进行药物敏感试验,头孢他啶与2-巯基丙酸协同试验筛选金属酶,多重PCR同时检测6种碳青霉烯酶耐药基因,对部分阳性产物进行测序比对,同时分析碳青霉烯酶基因上游插入序列。结果协同试验未检出产金属酶菌株。所有菌株都携带OXA-51-like基因,87株(86.1%)OXA-23-like基因阳性,2株OXA-24-like基因阳性,OXA-58-like基因与金属酶基因全为阴性。85株OXA-23-like基因上游检测到插入序列ISAba1,OXA-51-like基因上游未检测到ISAba1。结论 OXA-23和OXA-51组β-内酰胺酶基因是本组鲍曼不动杆菌最主要的碳青霉烯酶基因型,OXA-23组碳青霉烯酶基因与插入序列ISAba1关系密切。

Objective To detect the carbapenemase genotype and insertion sequence ISAba1 of imipenem-resistant strains of Acinetobacter baumanniis.Methods The antimicrobial susceptibility test for 101 strains of A.baumannii was conducted by Vitek-2 system.Metallo β-lactamases（MBLs）-producing strains were screened by ceftazidime and 2-mercaptopropionic acid synergy test.All the isolates were subjected to the multiplex PCR to detect 6 genes of carbapenemases.Results Among the 101 isolates,no MBLs-producing strain was found by synergy test.The positive rates of the blaOXA-51-like,blaOXA-23-like,blaOXA-24-like genes were 100%,86.1%（87/101）,2.0（2/101） respectively,while blaIMP-1,blaVIM-2 and blaOXA-58-like were all negative.The insertion sequence ISAba1 was only found in the up-stream of OXA-23-like gene of 85 strains,but no ISAba1 was detectable in the upstream of OXA-51-like gene.Conclusion OXA-23-like and OXA-51-like genes were the most popular genotypes of carbapenemase in the strains of A.baumannii in this hospital.The insertion sequence ISAba1 closely correlated with OXA-23-like gene of carbapenemase.