Abstract:ObjectiveTo investigate the epidemiologic characteristics and drug resistance mechanism of carbapenemresistant Acinetobacter baumannii (CRAB) isolated from a hospital, so as to guide prevention and control of healthcareassociated infection(HAI).MethodsA total of 32 CRAB strains isolated clinically from January 2010 to May 2012 were performed genotyping by randomly amplified polymorphic DNA fingerprinting, and epidemiological analysis was conducted; carbapenemase were screened by modified Hodge test and EDTAdisk synergy test. The effect of efflux pump inhibitor carbonyl cyanide mchlorophenyl hydrazone （CCCP）on minimum inhibitory concentration of meropenem was detected, efflux pump positive strains were screened.Results32 CRAB strains displayed 9 kinds of genotypes, type A, H, I,B, E, and other types were 10,7,4,3,3,and 1-2 isolates respectively. From March to May,2012, 11 CRAB strains were isolated, type H,I,and A were 7,3, and 1 isolates respectively. 21 (65.63%) CRAB strains expressed oxacillinase (OXA23), and were positive in modified Hodge test (including 11 strains isolated in MarchMay,2012); Except 1 isolate was detected New DelhiMetallo1(NDM1), all other strains were negative for metallolactamase test; the presence of CCCP slightly changed the MIC of meropenem to CRAB,all were negative for phenotype of efflux pump. CRAB strains were mainly isolated from patients in intensive care unit(13 isolates) and neurology department(7 isolates).ConclusionThe outbreak of HAI of the clone with identical genotype occurred in this ICU between March and May,2012. Carbapenemresistance mechanism of A. baumannii can be attributed to the expression of OXA23, and meropenemresistance is not related to the efflux pump, CRAB strain expressing NDM1 has been detected in this hospital.