Study Of Drug-resistant And Disinfectant-resistant Genes In Multidrug Resistant Acinetobacter Baumannii And Homology Analysis

Objective：To investigate the characteristic of antibiotic resistant genes in multidrugresistant Acinetobacter baumannii(MDRAB) isolated from clinical and explore the resistantmechanism for common disinfectants.Methods:(1) Multidrug-resistant Acinetobacter baumannii strains were collected from2009to2011and used for strains identification, antimicrobial susceptibility test.(2) Carbapenemage screening test was carried.(3) The resistance genes, including OXA-23, qacE△1, tnpU, aac6, ISAab1, bla OXA58,blaCTX-M, TEM-Q, SHV-Q, NDM-1were amplified by polymerase chain reaction（PCR）．(4) Pulsed-field gelelectrophoresis(PFGE) was used for homologous analysis ofmultidrug-resistant Acinetobacter baumannii isolated from RCU.(5)NDM-1resistance gene was connected to PMD18-T vector(6)Observe the killing effect of the common disinfectants (chlorine disinfectant,chlorhexidine acetate) on63strains of multi-drug resistant Acinetobacter baumannii.Study the mechanism of disinfectant resistancethe and expression ofdisinfectant-resistant genes in MDRAB. Results:(1)The strains, which collected from2009to2011, were multidrug-resistant Acinetobacterbaumannii. They were resistant to at least five of seven Anti-Pseudomonas bacteria drugs(penicillin, cephalosporins, aminoglycosides, carbapenem, tetracyclines, quinolones, andsulfonamides). The resistant rate was99%, they were multi-resistant to antibiotics.(2)The carbapenemase screening test showed that resistant strains producedcarbapenemase; the positive rate was67.7%.(3)Detecting of drug-resistant genes indicated that8genes were positive in drug-resistantstrains. The positive rates were as followed: aac6-93%, OXA23-87.1%, qacE△1-81.2%,tnpU-78.3%, ISAab-64.9%, TEM-62.8%, and SHV-21.1%. The positive rate of NDM-1was not available.(4)The homologous analysis showed that3strains which isolated from RCU belong to oneclone.(5)PMD18-T-NDM-1vector was constructed successfully.(6)Among the47strains out of63strains with multi-drug resistance,74.6%isolates werefound containing qacE△1-sull．When the concentration of chlorine disinfectant reached5000mg/L, all the strains of multi-drug resistant Acinetobacter baumannii were killed.Moreover, negative strains were restrained or killed when the concentration ofchlorhexidine acetate reached4-8mg/L.The difference between MIC and MBC was notobvious. While, positive strains could be restrained or killed when the concentration ofchlorhexidine acetate reached16mg/L.Conclusion(1)The mechanism of multidrug resistant Acinetobacter baumannii has turned to be acomplicated mechanism which was been mediated by many drug-resistant genes.(2)The strains isolated from RCU belong to one clone.(3)The common disinfectants could kill drug-resistant strains and the killing effect ofchlorhexidine acetate was related with the strains of carrying qacE△1-sul1gene.