Objective To study the molecular mechanism ofAcinetobacter baumannii resistant to carbapenem,to analyze the clinical features of carbapenem resistant A.baumannii (CRAB) bacteriaemia,and to provide evidence for infection control.Methods Blood culturing was carried out by the Bact/Alert 3D automated blood culture system.Then,identification and antimicrobial susceptibility tests were performed by the Vitek-2 compact system.CRAB isolates with MIC of imipenem and meropenem higher than 16μtg/mL were collected,and were re-identified by the Vitek-MS system (Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry,and MALDI-TOF MS).The presence of carbapenemase was screened by modified Hodge test.Carbapenemase genes (blaNDM,blaIMP,blaVIM,blaOXA-23,blaOXA-24,blaOXA-51 and blaOXA-58) were identified by PCR amplification and sequenced alignment.The clinical data were analyzed.Results A total of 27 patients with CRAB bacteremia were studied from June 2010 to May 2016.All strains of CRAB were resistant to most of the common antibiotics and were positive by modified Hodge test.Both blaOXA-23 and blaOXA-51 were detected in 25 strains of CRAB,while 2 strains harboring blaOXA-58.Strains were divided into three clusters by the Vitek-MS system (type Ⅰ-13 isolates,type Ⅱ-12 isolates,typeⅢ-2 isolates).Eighty-five percent of patients were hospitalized in intensive care units/beds.The primary source of infection was pulmonary inflammation (11 cases).All patients had a history of antibiotics use during 30 days before CRAB was isolated.The main antibiotics used were carbopenems,fluoroquinolones and cephamycins.The prognosis was not good and 15 patients died.Conclusion The resistance carbapenemase gene of CRAB in Xiamen area were mainly blaOXA-23 and blaOXA-51· CRAB bacteriaemia was mainly secondary to pulmonary inflammation.%目的 探讨血流感染的耐碳青霉烯类鲍曼不动杆菌(CRAB)耐药机制,分析菌株同源性及患者的临床特征,为CRAB的感染控制提供实验依据.方法 采用Bact/Alert 3D全自动血培养系统进行血培养,细菌鉴定和药敏使用Vitek-2 Compact全自动微生物分析系统.对2010年6月—2016年5月临床血流感染患者分离到的27株碳青霉烯类药物(亚胺培南和/或美罗培南MIC≥16μg/mL)耐药的CRAB复苏菌株,重新采用Vitek-MS质谱分析仪鉴定,采用改良Hodge试验检测碳青霉烯酶,PCR法检测B类酶基因(blaNDM、blaIMP和blaVIM)和D类酶基因(blaOXA-23、blaOXA-24、blaOXA-51和blaOXA-58)并测序比对.采用MALDI-TOF分析菌株同源性,并分析患者的临床资料及感染相关信息.结果 血流感染的CRAB绝大多数对常用抗生素耐药.27株CRAB改良Hodge试验均阳性.所有CRAB均未检测到B类酶基因(blaNDM、blaIMP和blaVIM);25株CRAB同时检测到blaOXA-23和blaOXA-51;另2株CRAB则为blaOXA-58阳性.采用Vitek-MS进行同源性分析,细菌分成3大簇(Ⅰ型13株、Ⅱ型12株、Ⅲ型2株).85.2％(25/27)患者来自重症监护病房或专科的监护病床,原发感染灶以肺部炎症最常见(11例).所有的患者在血培养出CRAB前的30d内均有抗菌药物使用史,使用频率较高的抗菌药物有:碳青霉烯类、氟喹诺酮类、头霉素类.15例CRAB血流感染患者死亡.结论 厦门地区的CRAB以D类产碳青霉烯酶OXA-23和OXA-51最为多见.CRAB血流感染的原发感染多为肺部炎症.
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