The Research Of Antibiotics Resistance And Phenotype Test In Producing Metallo-β-lactamase Clinical Pseudomonas Asaeruginosa Isolates

【Objective】1,Investigate the antimicrobial susceptibility of Imipenem-resistant Pseudomonas aeruginosa to instruct clinical application of antibiotics.2,Investigate and analyze occurrence of MBL in clinical Pseudomonas asaeruginosa isolates,and to explore and establish a simple and convenient method for screening MBL-producing Pseudomonas aeruginosa in the clinical microbe laboratory reasonably.【Methods】1,Pseudomonas aeruginosa strains isolated from Guangdong Provincial Hospital of Traditional Chinese Medicine,The first Affiliated Hospital of Guangzhou University of Chinese Medicine,Southern Medical University and The Second Affiliated Hospital of Sen Yat-sen University during 2005 to 2007 were collected and identified by VITEK-32 system.The minimal inhibitory concentrations(MIC)of them to 9 antibiotics,including Imipenem, Meropenem,Cefotaxime,cefepime,Gentamycin,Amikacin,Aztreonam, Ciprofloxacin,Levofloxacin were detected by agar dilution method.2,MBL gene was detected by PCR method using primers specific for blaIMP,blaVIM, blaGIM-1 and blaSPM-1,respectively,and the PCR products were purified and sequenced.3,The inhibitor-potentiated disk diffusion test using substrate Imipenem and Cefatazimide,enzyme inhibitor EDTA-Na₂ and 2-mercaptoethanol, which was established and the results were evaluated with those of PCR.【Results】1,From May 2005 to May 2007 a total of 440 strains of Pseudomonas aeruginosa were obtained from 4 major hospitals in Guangzhou.Most of isolates were recovered from patients in the ICUs(40.68%).The isolates were mainly recovered from respiratory secretions(66.36%).81 of the isolates were resistant to Imipenem(18.41%).2,There is much higher drug resistance rate of Imipenem Resistances than Imipenem non-Resistances,especially in gentamicin(10.86%,65.43%),ceftazidime(10.03%53.09%)and Amikacin (12.26%53.09%).3)114 Imipenem-resistant or ceftazidime-resistant Pseudomonas aeruginosa were screened for MBL production,and 26 of them were positive.One of the positive isolates was confirmed being blaVIM-2 by DNA sequencing,and the others were blaIMP positively.3,Compared with PCR, Ceftazidime-EDTA disk synergy test showed high sensitivity(92.31%)and specificity(99.15%)with EDTA of 0.25μmol/disk.4,Isolates producing MBL possed wide resistance profile.They resisted to most aminoglycosides and Cephalosporins antibiotics.Only were they still sensitive to quinolones andβ-lactams.【Conclusion】Pseudomonas aeruginosa to imipenem resistance rate remained at a relatively high level and a rising trend year by year.Resistance of imipenem-resistant strains of the resistance group was significantly higher comparing with non-group imipenem-resistant strains.114 imipenem and(or) ceftazidime-resistant the Pseudomonas aeruginosa bacteria use PCR test to detect MBL-coding.Study results showed that tested bacteria may be in the IMP-oriented and a level of communication trends.We should strengthen the capacity of detection and monitoring.MBL detection rate was only 18.06 percent, and it could not be considered as most important reason for resistance of Pseudomonas aeruginosa.The specificity and sensitivity of CAZ-EDTA disc synergy in metal detection can be comparable with the PCR technique,and the synergy method have a certain significance for clinical microbiology laboratories routine identification of MBL in Pseudomonas aeruginosa.