4 years migration of Acinetobacter baumannii and mechanisms of resistance to Imipenem from 2007 to 2010

Objective To study the migration of Acinetobacter baumannii resistance in our hospital from 2007 to 2010 and to explore the mechanism of drug resistance to imipenem.Method The Strain identification and antibiotic susceptibility of bacteria was analyzed by VITEK 2 automatic analyzer.Resistant genes such as blaOXA-51,blaOXA-23,blaOXA-24 and blaOXA-58 were determined by PCR.Result The resistance of 811 clinical Acinetobacter baumannii isolates to antibiotics,such as cefoperazone/sulbactam,imipenem,meropenem,cefepime,piperacillin-tazobactam,were getting higher year by year.The imipenem-resistance rate of the Acinetobacter baumannii strains from 2007 to 2010 was 13.1%,26.0%,44.3% and 59.5%,respectively.Of the 811 clinical Acinetobacter baumannii isolates,311(38.3%) were resistant to imipenem.Imipenem-resistant Acinetobacter baumannii isolates showed the highest sensitivity to amikacin,followed by cefoperazone/sulbactam.The susceptibility rate to cefoperazone/sulbactam decreased significantly.The positive rates of detected genes were as follows: blaOXA-51(89.3%),blaOXA-23(20.7%),blaOXA-24(2.14%),blaOXA-58(15.7%).Conclusion The resistance rate of Acinetobacter baumannii to antibiotics was increasing year by year.Combination therapy of cefoperazone/sulbactam plus amikacin is usually an effective treatment for infection by Acinetobacter baumannii.Producing carbapenemases is the major resistance mechanisms of IRAB.