| [Backgroud]Acinetobacter baumannii has emerged as an important nosocomial pathogen that is responsible for a variety of nosocomial infections, comprising bacteremia, urinary tract infection, secondary meningitis, surgical-site infection, and nosocomial and ventilator-associated pneumonia. In recent years, several outbreaks of nosocomial infections patients, especially in intensive-care-unit (ICU) and blood ward caused by carbapenem-resistant A. baumannii have been documented. Because of the multiple antibiotic resistance exhibited by A. baumannii, nosocomial infections caused by this organism are difficult to treat. It is signification to investigate the molecular epidemiology and phenotypic of A.baumannii colonization and infection and to study the antibiotic resistant mechanisms in these strains.[Objective] To screen multidrug-resistant clinical isolates of acinetobacter baumanii and to investigate the resistant phenotypes and mode of these isolates. Study the affection of efflux inhibitor on the fluoroquinolones and aminoglycosides against Acinetobacter baumannii. To investigate the efflux gene and its DNA sequence. Detect the OMP of Acinetobacter baumannii and assay its relationship to multi-drug resistant.[Methods] (1)The standard agar dilution susceptibility tests was carried out on Mueller Hinton agar according to CLSI guidelines to determine minimal inhibition concentration(MIC) of 24 antimicrobial agents against total acinetobacter baumanii. Random Amplified Polymorphic DNA (RAPD) typing was used to investigate the homology of the resistant isolates.(2)MICs .of antibiotics that of fluoroquinolones and aminoglycosides combined CCCP and reserpine against Acinetobacter baumannii were assayed by two-fold agar dilutionmethod. (3)Specificity primers of adeB were designed to detect incidence of efflux pump gene by PCR among 6 clone isolates of Acinetobacter baumanii. The DNA sequencing were BLAST on GeneBank (http://www.ncbi.nlm.nih.), analyze drug resistant gene type and arrangement in adeB gene, explore molecule mechanism of carbopenems-resistant acinetobacter baumanii. (4)0MP of multi-drug resistant Acinetobacter baumannii were extracted to assay its relations by SDS-PAGE.[ Results ] (1) 87 strains of Acinetobacter baumanii were identified by biochemical and Vitek system. 68 strains of mutli-resistant acinetobacter baumanii were screened by Standard disk diffusion susceptibility tests. (2) Genotypic analysis of 68 strains of mutli-resistant acinetobacter baumanii by RAPD revealed 6 patterns named A to F, including 5,8,5,47,2, 1strain(s),respectively.(3) Efflux pump ihibitor (reserpine and CCCP)enhanced the activities of fluoroquinolones and aminoglycosides,especially the affection of efflux pump inhibitors against LVX and GAT were much stronger.The affections of reserpine and CCCP against LVX and GAT were significant statistics difference by variance analysis. (4) The efflux pump gene adeB were detected by PCR except B clone.The sequences of these PCR amplification products were 99% identical to previously published sequences of adeB (GeneBank AF370885.1.).(5) OMP of 68 multi-drug-resistant strains were" detected by SDS-PAGE electrophoresis, there were straps absence on 28KDa among 32 strains.[Conclusion] The present study reveals that detection rate of mutli-resistant acinetobacter baumanii has been raisen rapidly, susceptivity of carbapenems antibacterials descent obviously and drug resistance of other antibacterials of III, IV generation cephalosporins and enzyme inhibitor compound decreased remarkably.The resistant ratio to sulfamido and aminoglycosides were high. (2) Efflux pump inhibitor(reserpine and CCCP) can decrease the fluoroquinolones MICs of Acinetobacter baumannii.(3) RAPD showed that there were obviouslydifference on multi-drug resistant resources.(4)PCR amplification of adeB gene showed positive, DNA sequencing were 99% identical to previously published sequences of adeB (GeneBank AF370885.1.).(5) OMP absence were observed among multidrug resistant Acinetobacter baumannii.
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