| Objective To investigate distribution and antibiotic resistance of clinical isolated Acinetobacter baumannii in Changsha and molecular epidemiological characteristics of the carbapenem-resistant isolates among them. In order to provide guidance for rational use of antibiotics, preventing and controlling of the prevalence of these mutidrug resistance strains.Method Totally205Acinetobacter baumannii isolates were collected from March2010to December2010from10general hospitals in Changsha. K-B disk diffusion method was applied for the drug susceptibility test, modified double-disk synergy test was used to detect metallo-β-lactamase (MBL), and modified Hodge test was used for the screening of carbapenemase. PCR was used for amplification of carbapenemase genes included:OXA-23, OXA-24, OXA-51, IMP-1and VIM-2, and the positive products were sequenced. Enterbacter repetitive intergenic consensus PCR (ERIC-PCR) was used fro DNA typing and homology analysis.Results1. Among205strains of Acinetobacter baumannii,173(84.4%) were from sputum and bronchial secretions, followed by13(6.3%) from wound secretions. The number of strains isolated from the intensive care unit was the highest that accounted for42.0%(86), followed by the neurosurgery department and the respiratory department which accounted for15.1%(31) and13.2%(27) respectively.2. The resistance rates to14of the18antibiotics tested were higher than50%. Resistance rate of piperacillin was the highest (80.5%), and of cefoperazone/sulbactam was the lowest (2.5%).3.Totally115carbapenem-resistant Acinetobacter baumannii strains were confirmed, but their MBL phenotype and genes were all negative. Modified Hodge test detected71positive strains, among which64 strains were OXA-23positive. All the115strains were positive for the amplification of OXA-51gene, and there was no strain carry OXA-24and OXA-58gene.4. The115Acinetobacter baumannii were divided into7genomic types (A, B, C, D, E, F, G). The major prevalence types were type B contained72stains and type A contained19strains. Type A contained subtype A1(11) and A2(8), while type B contained subtype B1(54) and B2(18). There were7stains belonged to type G,5belonged to type C and4belonged to type F, D and E, respectively.Conclusions (1) Clinical isolated Acinetobacter baumannii in Changsha keep relative high sensitivity to cefoperazone/sulbactam, but are high resistant to other antibiotics including carbapenems, and multiple drug resistance is serious.(2) The major carbapenemase genotype of clinical isolated Acinetobacter baumannii in this area are OXA-23and OXA-51. Produce of OXA-23and OXA-51carbapenemases is an important resistance mechanism for carbapenems antibiotics.(3) There are prevalence of the same clones in these carbapenem-resistant strains in this area, and two clones is the major prevalence types. |
