| Purpose:To investigate nosocomial distribution, prevalence of carbapenemase gene and the molecular epidemiological characteristics of Acinetobacter baumannii (Aba) isolated from in-hospital patients.Materials and Methods:Whonet5.4 software was used to screen the strain information from the lab database, all the nonrepetitive isolates of Aba were isolated from different body sites (sputum samples were excluded) between January 2007 and December 2009. The nosocomial distribution and antibiotic resistance rate determined by K-B method were analyzed; genes of carbapenemase and the class I integrons were amplified by PCR and its products were sequenced. Epidemiological genotypes of the resistant isolates selected were analyzed by pulse-field gel electrophoresis (PFGE). Besides, Nonrepetitive Aba strains with complete clinical data causing bloodstream infection (BSI) between January 2007 and October 2010 were collected. All the BSI strains were analysed by detecting the carbapenemase genes and New Delhi metallo-β-lactamase-1(NDM-1) gene, and the molecular genotypes were determined by PFGE;10 representative strains covering all the 6 PFGE genotypes selected were further genotyped by multilocus sequence typing (MLST).Meanwhile, distribution of BSI risk factors among patients were preliminary analysed after investigating patients'clinical data.Results:427 Aba strains among the 510 strains collected were identified as Multi-drug Resistant Acinetobacter baumannii(MDRAB), all the Aba strains maintained fairly high resistant rate (68.8%～84.9%) to 13 antibiotics except cefoperazone/sulbactam and Minocycline with resistant rates of 24.7% and 34.4% respectively. Gene detection showed that among the 194 selected MDRAB strains,100% carried blaOXA-51-like gene,96.4%(187)carried Class 1 integron,84.5%(164)strains carried blaOXA-23 gene and 1strain possessed blaOXA-58-like gene, the blaOXA-24-like gene was not detected;PFGE showed that 194 strains tested were divided into 16 different genotypes, type A and type B played dominant role in epidemiology, type A existed in three years, whereas, type B and type H increased significantly, and type B was the most common genotype in 2009.70 nonrepetitive Aba BSI strains with complete clinical information were collected between January 2007 and October 2010. Gene detection showed that 100% carried blaOXA-51-like genes,88.6%(62) possessed blaOXA-23-like genes,and blaIMP,blaVIM,blaSIM,blaOXA-58-like and blaOXA-24-like were not detected. PFGE demostrated that all the 70 strains were divided into 6 different genotypes, genotype A and B played dominant role in prevalence. MLST indicated that 10 stains were divided into 4 sequence types(STs),7 strains were ST2,3 strains were ST104,ST105 and ST106 which were new STs discoverd in this study. 88.6% patients experienced more than one catheter-related invasive processures, and 92.9% were administered antibiotics.Conclusion:The number of Aba strains isolated from our hospital increased rapidly and exhibited high antibiotic resistant rate. Most MDRAB strains carried blaOXA-23 type carbapenemase, and different clones can be found among clinical departments, the most prevalent genotypes were clone A and clone B determined by PFGE and were ST2 by MLST.The main genotypes of strains isolated from blood and other body sites were the same, however, percentage of MDRAB stains isolated in blood was higher, Most BSI patients have undergone severe underlaying diseases and several invasive procesures together with a great quantity of antibiotics administratation before infection happens.
|
PDF Full Text Request