泛耐药鲍氏不动杆菌碳青霉烯酶基因型研究

Study on carbapenemase genotypes of pan-drug-resistant Acinetobacter baumannii

目的研究医院泛耐药鲍氏不动杆菌(PDRAB)不同克隆的耐药性及碳青霉烯酶基因型特征,为有效治疗和控制PDRAB医院感染提供参考资料。方法应用脉冲场凝胶电泳(PFGE)技术对PDRAB进行分子分型,E试验法检测PDRAB各克隆最低抑菌浓度(MIC)值,聚合酶链反应(PCR)及核酸测序确定PDRAB各克隆碳青霉烯酶基因型。结果 90株PDRAB分子分型出现A、B、C、D、E 5种克隆,A、C克隆出现亚型,A、C、E克隆为主要流行株,分别占70.0%、7.8%、14.4%;各型克隆均对多黏菌素B敏感,部分流行克隆对米诺环素、阿米卡星敏感,其余抗菌药物均表现高水平耐药;A、C及C亚型克隆携带blaOXA-23、blaOXA-51和blaPER-1基因,A亚型、D克隆携带blaOXA-23和blaPER-1基因,B克隆携带blaOXA-51和blaPER-1基因,E克隆携带blaOXA-23、blaOXA-51和blaGIM-1基因,未发现携带blaOXA-24、blaOXA-58、blaIMP、blaVIM及blaSPM-1基因的PDRAB克隆。结论医院PDRAB流行克隆存在多样性,各克隆耐药表型及碳青霉烯酶基因型有所不同,产生OXA-23酶和PER-1金属酶是该地区PDRAB耐药的主要机制。

OBJECTIVE To study the antibiotic resistance and carbapenemase genotypes of pan-drug-resistant Acinetobacter baumannii（PDRAB）,and provide reference for treatment and control of hospital-acquired infections.METHODS The strains of PDRAB were typed by pulsed-field gel electrophoresis（PFGE）.The minimal inhibitory concentration of PDRAB clones were examined by E-test method.The carbapenemase genotypes were analyzed by PCR and verified by DNA sequencing.RESULTS Among 90 strains of PDRAB,PFGE identified five different strain types,which were clone A,B,C,D and E,respectively.The clone A and C showed subtypes.The clone A,C and E were epidemic strains,which constituent ratios were 70.0%,7.8% and 14.4%,respectively.All clones were susceptible to polymixin B.Several epidemic clones were susceptible to minocycline or amikacin.Other antimicrobial agents showed high-level resistance.The clone A,C and subtype C carried blaOXA-23,blaOXA-51 and blaPER-1 genes.The clone subtype A and clone D carried blaOXA-23 and blaPER-1 genes.The clone B carried blaOXA-51 and blaPER-1 genes.The clone E carried blaOXA-23,blaOXA-51 and blaGIM-1 genes.No PDRAB clones were found to carry blaOXA-24,blaOXA-58,blaIMP,blaVIM and blaSPM-1 genes.CONCLUSION The PDRAB clones show the diversity in our hospital.The drug resistance phenotypes and carbapenemase genotypes are different among PDRAB clones.OXA-23 oxacillinase and PER-1 metallo-β-lactamase are the dominant carbapenem resistant mechanisms for PDRAB strains in this area.