In Vitro Activity Of Antimicrobials Combination Against Carbapenem Resistant MDR-AB And Detection Of Metallo Enzyme Genes

To investigate the drug resistance and in vitro activity of 35 strains of multidrug-resistant Acinetobacter baumannii in the First Affiliated Hospital of Jinzhou Medical University,further detecting the metallo beta lactamase genes.MethodsThe experimental bacterial strains were separated from various clinical specimens of The First Affiliated Hospital of Jinzhou Medical University during August 2016 to March 2017.Investigating the drug resistance for 35 strains of multidrug-resistant Acinetobacter baumannii by microdilution method.Metal enzyme genes of strains were tested by polymerase chain reaction(PCR).The positive products of PCR were sequenced to determine the gene type.The minimum inhibitory concentrations(MICs)of antibiotics used combination for 35 strains of MDR-AB seperated in clinic were determined by broth microdilution method and checkerboard method.The Fractional Inhibitory Concentration(FIC)index was calculated according to MIC results and analyzed by statistical methods.Results1.MDR-AB detection rate was the highest in ICU,followed by department of respiration,respectively accounted for 73.4%(26/35)and 17.1%(6/35).2.The resistance rate of Cefoperazone / Shubatan(CFS),piperacillin / Shubatan(SPI),ampicillin / sulbactam(SAM),meropenem(MER),biapenem(BPM),imipenem(IPM),fosfomycin(FOS),etimicin sulfate(ETS)against MDR-Ab was all 100%.The resistance rate of Li Fuping(RIF),levofloxacin(LVX),Shubatan(SUL),tigecycline(TIG),polymyxin B(PMB),Amikacin(KAN),gentamicin(GEN)and minocycline(MIN)against MDR-Ab wasrespectively31.4%,80%,91.4%,71.4%,42.9%,94.3%,94.3% and 5.7%.3.The positive products of NDM-1,IMP-1,VIM-1,VIM-2,GIM and SPM 6 kinds of metallo beta lactamase gene amplification by PCR were checked by electrophoresis.Of which 26 strains were found in 263 bp positive bands,suggesting that these strains may carry IMP-1 gene,the positive rate was 74.3%(26/35).There were 13 strains at about 285 bp positive bands,suggesting that these strains may carry VIM-2 gene,the positive rate was 37.1%(13/35).There were 11 strains simultaneously carrying IMP-1 and VIM-2 genes.4.The PCR positive products were slelected to be be purified and sequenced in Dalian Baosheng biology company.The homology was 99% compared with known IMP-1 and VIM-2 genes reported on GeneBank.Therefore,the genes were confirmed as IMP-1 and VIM-2 genes.5.The combanations of SUL,CFS and TIG respectively with other antibiotics show synergistic,added or not related efection and there is not antagonistic action.The synergistic rate was higher in the group combined with MER than other grous(P<0.05).Conclusions1.These 35 strains of multidrug-resistant Acinetobacter baumannii multiple carrying blaIMP-1 and blaVIM-2 genes in this study,which maybe affiliated with the resistance of carbapenem on these strains.2.The combanations of SUL,CFS and TIG respectively with other antibiotics show synergistic,added or not related efection and there is not antagonistic action.The main component which plays a major role against MDR-AB in CFS is SUL.MER combined with SUL,CFS,TIG has higher rate of cooperation compared to BPM and IPM.