A multicenter study of hospital infection with carbapenem-resistant Acinetobacter baumannii

Abstract

Objective To investigate the epidemiologic features of interhospital, intrahospital, interdepartmental and intradepartmental infections of carbapenem-resistant Acinetobacter baumannii (CRAB) isolated from clinical specimens. Methods From September 2015 to September 2016, 540 non-repetitive strains of Acinetobacter baumannii were clinically isolated from 38 tertiary hospitals in Anhui Province, of which 460 strains were confirmed by antimicrobial resistance surveillance in Anhui Province. Agar plate dilution method was used to determine the MIC of 16 antibiotics and to select 312 CRAB isolates for drug sensitivity test. Pulsed field gel electrophoresis (PFGE) was used to analyze homology of 145 strains. PCR and clonal sequencing were used to determine the corresponding genotypes. Results All the 312 CRAB strains were multiple antibiotic resistant strains. The drug resistance rates to imipenem and meropenem were 67.9% and 70.6%, respectively. All the 145 strains were divided into 80 different types (PT1-PT80) by PFGE. Only one strain was found in the 60 types and two or more strains were found in the other 20 types. Genotype blaOXA-51 was detected in 145 strains (100%), genotype blaOXA-23 was detected in 134 of strains (92.41%), genotype blaOXA-24 was detected in 1 strain (0.69%), and subtype of blaIMP-4 was detected in 4 strains (2.76%). Genotype blaOXA-58, blaVIM, blaSIM, blaNDM and blaKPC were undetectable. Conclusions Homologous analysis indicates that all 145 strains of CRAB exhibit the interhospital, intrahospital, interdepartmental and intradepartmental transmission. Genotype blaOXA-51 is the inherent drug resistant associated gene in the chromosome of AB and genotype blaOXA-23 is the most common carbapenemase gene in Anhui Province and the main genotypes of resistance transmission. Key words: Acinetobacter baumannii; Drug resistance; Cross infection; Carbapenemase; PFGE