鲍曼不动杆菌的耐药率变迁及 CRAB 耐药机制研究

摘要

目的：分析南昌大学第一附属医院鲍曼不动杆菌的耐药率变迁，并研究耐碳青霉烯类鲍曼不动杆菌（car-bapenem-resistant acinetobacter baumannii，CRAB）的耐药机制，为临床抗生素的使用提供依据。方法采用VITEK-2-COMPACT 全自动微生物鉴定仪进行细菌鉴定及药敏测定，分析2010年及2014年南昌大学第一附属医院鲍曼不动杆菌对临床常用抗生素的耐药分布；同时，选取临床分离的非重复耐碳青霉烯类鲍曼不动杆菌进行耐药机制研究，应用多重聚合酶链反应（PCR）扩增 IMP、VIM、OXA-23、0XA-24、0XA-51、OXA-58、IsAba1-blaoxa-23基因，明确该院鲍曼不动杆菌中主要碳青霉烯酶基因表达及其与插入序列 IsAba1的关系。结果与2010年相比，2014年检出的鲍曼不动杆菌对大部分临床常用抗生素的耐药率均有上升趋势（除外左氧氟沙星及复方新诺明）；随机选取临床分离的非重复耐碳青霉烯类鲍曼不动杆菌70株和1株对碳青霉烯类敏感的敏感株参照株（car-bapenemase sensitive acinetobacter baumannii，CSAB）共71株，用7对特异性引物对70株耐碳青霉烯类鲍曼不动杆菌和1株敏感对照株进行 PCR 扩增检测显示，70株 CRAB 及 1株敏感菌株中均携带有 OXA-51，而仅在 CRAB中检出 OXA-23、IsAba1-blaOXA-23基因，敏感对照株中未检出该两个基因表达；OXA-58基因在6株 CRAB 中有表达，均未检出 VIM，IMP，OXA-24基因。结论南昌大学第一附属医院鲍曼不动杆菌对临床常用抗生素的耐药性有上升趋势，需进一步加强合理使用抗生素，同时耐碳青霉烯类鲍曼不动杆菌主要耐药基因为 bla OXA-23和bla OXA-51，前者可能与 bla OXA-23上游存在插入序列 IsAba1有关，后者则可能与其上游存在强启动子导致高表达有关，而 CRAB 耐药与金属酶、OXA-24、OXA-58基因无明显相关性。%ABSTRACT:Objective To analyze the drug resistance transition of Acinetobacter baumannii (AB)in the First Affiliated Hospital of Nanchang University,and to investigate the drug resist-ance mechanisms of carbapenem-resistant AB for providing a basis for clinical use of antibiotics. Methods Bacteria identification and drug susceptibility determination were performed using VITEK-2-COMPACT automatic microorganism identification machine to analyze the antibiotic resistance distribution of AB in 2010 and 2014.Meanwhile,non-repeated carbapenem-resistant AB (CRAB)was selected to investigate the drug resistance mechanisms.The IMP,VIM,OXA-23, OXA-24,OXA-51,OXA-58 and IsAbal-bla oxa-23 genes were amplified by PCR to explicate the expression of major carbapenemase genes in AB and its relationship with insert sequence IsAba1. Results Compared with 2010,the rate of resistance of AB to most of the clinical commonly used antibiotics increased in 2014(except levofloxacin and SMZco).The target genes were amplified by PCR with 7 pairs of primers in 70 strains of CRAB and 1 strain of carbapenem-sensitive AB (CS-AB).The results indicated that all the strains carried OXA-51.However,OXA-23 and IsAba1-blaOXA-23 genes were detected only in CRAB.OXA-58 gene was detected in 6 strains of CRAB. No VIM,IMP,and OXA24 genes were detected in all the strains.Conclusion The rate of drug re-sistance of AB to the clinical commonly used antibiotics shows a rising trend in the First Affiliated Hospital of Nanchang University.Therefore,the rational use of antibiotics needs to be further strengthened.The bla OXA-23 and bla OXA-51 were the main resistance genes of CRAB.The for-mer may be correlated with upstream insertion sequence IsAba1,and the latter may be correlated with strong promoter-caused overexpression.The resistance of CRAB is not associated with metal enzyme,OXA-24 and OXA-58 genes.