ICU患者感染鲍曼不动杆菌对碳青霉烯类抗生素的耐药性及相关耐药基因分析

Analysis of the resistance of Acinetobacter baumannii to carbapenem antibiotics in patients in the ICU and analysis of genes related to its drug resistance

目的分析医院ICU病房患者感染鲍曼不动杆菌的耐药性及耐药基因,以指导临床抗感染治疗合理用药,更好地控制ICU病房感染发生。方法从本院ICU患者的相应部位收集标本,分离鉴定鲍曼不动杆菌,采用纸片扩散法对其进行碳青霉烯类抗菌药物耐药性分析。从分离菌株提取基因组DNA,并设计相应引物,采用PCR扩增OXA-23、OXA-24、OXA-51、OXA-58和NDM-1金属酶基因,对OXA-23基因和NDM-1金属酶基因扩增产物进行纯化并测序。结果 67株ICU病房患者感染鲍曼不动杆菌临床分离株对亚胺培南、美罗培南、帕尼培南、法罗培南、厄他培南、比阿培南的耐药率分别为86.0%、59.0%、71.0%、42.0%、39.0%和53.0%。PCR扩增鲍曼不动杆菌的OXA-23型酶基因片段大小为796bp、OXA-51型酶基因片段为862bp、OXA-58型酶基因为912bp、NDM-1金属酶基因片段为287bp,未扩增出OXA-24型酶基因。对纯化的OXA-23型酶基因和NDM-1金属酶基因PCR产物测序,得到相应的序列基因。结论本院ICU病房患者感染的鲍曼不动杆菌对碳青霉烯类抗菌药物产生了不同程度的耐药性,这与患者长期大量使用此类药物有关。该分离菌耐药基因携带率较高,治疗时应合理选用药物。

Objective To analyze the drug resistance of Acinetobacter baumannii infecting patients in the ICU at this Hospital in order to further understand its drug resistance,to guide the rational selection of antibiotics for clinical treatment of infections,and to better control the incidence of infections in the ICU. Methods Specimens were collected from different parts of the body of patients in the ICU at this Hospital.Pathogens were isolated and identified.The resistance of A.baumannii to carbapenem antibiotics was analyzed using the disc diffusion method.Genomic DNA was extracted from the isolated strains,primers were designed,and the OXA-23 gene,the OXA-24 gene,the OXA-51 gene,the OXA-58 gene,and the NDM 1metallo-β-lactamase gene were amplified with PCR using given thermal cycle parameters.The products of amplification were subjected to electrophoresis to yield results.Products of amplification of the OXA-23 gene and the NDM-1metallo-β-lactamase gene were sequenced. Results Resistance to antimicrobials was determined based on corresponding critical values according to CLSI standards.Sixty-seven strains of A.baumannii were isolated from patients in the ICU.A.baumannii resistance to imipenem was 86.0%,its resistance to meropenem was 59.0%,its resistance to panipenem was 71.0%,its resistance to faropenem was 59.0%,its resistance to ertapenem was 39.0%,and its resistance to biapenem was 53.0%.Thus,A.baumannii had developed varying degrees of resistance to carbapenem antibiotics.Resistance to imipenem was highest,and this might be related to its extensive use over a prolonged period.Amplification with PCR and electrophoresis indicated that the OXA-23β-lactamase gene of A.baumannii was 796 bp in length,the OXA-51β-lactamase gene was 862 bp,the OXA-58β-lactamase gene was 912 bp,and the NDM-1metallo-β-lactamase gene was 287 bp.The OXA-24β-lactamase gene was not amplified.The OXA-23β-lactamase gene and the NDM-1metallo-β-lactamase gene were sequenced to further understand the genes producing drug resistance in A.baumannii,to better analyze the mechanisms for that resistance,and to guide drug use to control infection. Conclusion A.baumannii infecting patients in the ICU at this Hospital had developed varying degrees of resistance to carbapenem antibiotics,and this was related to the extensive use of those drugs.Analysis of drug resistance genes should help to better control the development of drug resistance and guide rational drug use in clinical settings.