Analysis Of Antimicrobial Agents Resistence Of Acinetobactoer Baumanii And Class D Carbapenemeases Genotypes And Homology

OBJECTIVE To investigate the antimicrobial resistence of Acinetobacter baumanii from the lower respiration tract,and guide rational use of antimicrobial agents to clinical therapy. To investigate the class D carbapenemases genotypes and homology of imipenem-resistant Acinetobacter baumanii,and analysis the molecular epidemiological characteristics of nosocomial resistant isolatesMETHODS Totally clinical isolates were collected from lower respiration tract of the First Affiliated Hospital of Anhui Medical University in 2009.Microscan WalkAway-40automatic microbial analysis system and Negative Combo Panel Type 31 was applied to species identification and antimicrobial susceptibility testing.The sensitivity detection of cefoperazone/sulbactam and minocycline was performed by K-B disk diffusion method. Polymerase chain reaction(PCR) assay was performed for the detection of genes encoding for OXA-23-like, OXA-24-like, OXA-51-like, OXA-58-like carbapenemase of imipenem-resistant Acinetobacter baumanii.And enterobacterial repetitive consensus PCR(ERIC-PCR) was performed for stain identification.RESULTS The lowest resistance rate of Acinetobacter baumannii to antimicrobial agents was cefoperazone/sulbactam(24.1%),then was minocycline(29.1%) and imipenem (35.2%) And to imipenem-resistant isolates the lowest rate was to cefoperazone/sulbactam(37.5%), then was to minocycline (54.7%).All isolates showed 100% resistance to ceftriaxone,cefotaxime, piperacillin/tazobactam,piperacillin,and ticarcillin/clavulanic acid. The resistance to other antimicrobial agents were more than 80%.In 64 imipenem-resistant Acinetobacter baumanii,57 isolates(89.1%) harbored blaOXA-66/blaOXA-51-like,51 isolates (79.7%) were positive for blaOXA-23, and 4 strains were blaOXA-58 positive, blaOXA-24 was not dectected in these strains. The positive strains carrying blaoxa-23+blaoxa-66+blaoxa-58 gene, blaoxa-5s+blaoxa-66 gene and blaoxa-23+blaoxa-66 gene were 1,3,50 respectively.Patterns of ERIC-PCR were same in 47 isolates which harbored blaOXA-23.All 51 isolates had a genetic relationship.2 strains carrying blaOXA-58 were the same genetype.CONCLUSIONS Most of A.baumanii isolates are susceptible to cefoperazone/sulbactam, minocycline, and imipenem.All imipenem-resistant isloates are multidrug resistant.The resistance rate to cefoperazone/sulbactam is lower than to other antimicrobial agents. OXA-23 carbapenemase is the most prevalent enzyme in imipenem-resistant A.baumanii.Clone dissemination seems to be the most important way of strains spread.