Study On Carbapenem-resistant Acinetobacter Baumannii Resistance Mechanisms In Partical Areas Of JiangXi Province

Objective:To investigate the genotype characteristics and the relationship between the most common genotype and insertion sequence Isabal of carbapenem-resistant acinetobacter baumannii from Jiangxi province in order to explore the resistant mechanisms of carbapenem-resistant acinetobacter baumannii.Methods:A total of 140 non-repeat clinical isolates of carbapenem-resistant acinetobacter baumannii and 1 carbapenem antibiotic-sensitive strains used as a control were continuously collected during January-December 2010 from 4 first-class hospitals at gradeШamong 3 different regions of Jiangxi province. Agar dilution method was used to determinate the antibiotic susceptibility. Metal enzyme of acinetobacter baumannii was detected by 2-mercaptopropionic acid inhibition test. IMP. VIM, OXA-23, OXA-24, OXA-51, OXA-58 and Isabal-bla oxa-23 genes were amplified and analyzed by PCR and sequencing, in order to clear the expression of major carbapenemase genes of acinetobacter baumannii and its relationship with insert sequence Isabal in Jiangxi province.Result:140 non-repeat strains of carbapenem-resistant acinetobacter baumannii which all contributed to hospital-acquired infections were recovered from the patients of Intensive Care Unit(62), Respiratory Medicine(57), Burn Unit(16) and Senior officials inpatient Ward(1) in Jiangxi province. The drug resistance rate of acinetobacter baumannii to 22 kinds of antibiotics was high. It was only relatively sensitive to polymyxin(100%) and cefoperazone-sulbactam(95%) respectively. There was not significant synergistic effect between 2-mercaptopropionic acid and cefoyazidine. The metal enzymes (aβlactamase) were not detcated in all strains. The DNA of the strains were amplified by PCR using 7 pairs of specific primers. Genetic analysis showed that all strains carrying OXA-23, OXA-51, IMP, VIM and 6 of which carrying OXA-58, not containing OXA-24. Unlike the sensitive strains, all isolates of carbapenem-resistant acinetobacter baumannii express Isabal-blaoxa-23 gene.8 bla oxa-23-like positive strains,8 bla oxa-51-like positive strains,8 Isabal-blaoxa-25 positive strains and 6 bla oxa-58-like positive strains were randomly selected for DNA sequencing. The results of homology to Genbank were 100%(GQ861439.1),99%(EU255296.1),100%(GQ849192.1) and 85%(CP002522.1) respectively.Conclusion:Carbapenem-resistant acinetobacter baumanniies are mainly distributed in Intensive Care Units and Respiratory Medicine of hospitals in Jiangxi Province, and the multi-drug resistance is becoming a serious problem. In this study, we find that carbapenem-resistant acinetobacter baumanniies are only more sensitive to polymyxin. cefoperazone-sulbactam and levofloxacin resistant to other antibacterial drugs. The antibiotic resistance may be caused by expression of resistance genes such as bla OXA-51, bla OXA-23 and Insert sequence IsAbal exists upstream of bla OXA-23, however, the metal enzyme, OXA-24 and OXA-58 genes are not relevant.