Detection Of Beta-lactamases In Multi-resistant Pseudomonas Aeruginosa And Study Of The Mechanisms In Imipenem-Resistant Pseudomonas Aeruginosa

Objective To analyze the distribution, drug resistance and beta- lactamases of clinical multi-resistant Pseudomonas aeruginosa isolated from the First Affiliated Hospital of Anhui Medical University, and offer reasonable experimental data for clinical therapy. Methods Standard agar dilution was used to determine the minimal inhibitory concentration (MIC) of 106 strains of multi-resistant Pseudomonas aeruginosa isolated clinically. Phenotype of beta -lactamases was detected by modified three dimensional test of the106 strains of multi-resistant Pseudomonas aeruginosa. Results Multi-resistant Pseudomonas aeruginosa isolates majorly came from upper respiratory tract(sputum and throat mucus),and 106 strains multi-resistant Pseudomonas aeruginosa resistant rate followed by ciprofloxacin(95.3%), levofloxacin and Gentamicin (93.4%),aztreonam (90.6%),piperacillin(78.4%), imipenem(74.5%), meropenem(64.2%), and ceftazidime(51.9%) to routine antibiotics clinically. There were 17 strains ESBLs-producing, 4 strains AmpC-producing, and 2 strains MBL-producing respectively, and 2 strains were both ESBLs-producing and MBL-producing strains detected by modified three-dimensional tests in these producted beta–lactamases strains. Conclusions Multi-resistant Pseudomonas aeruginosa shows high resistance rates to many antibiotis. There are three kinds beta -lactamases in multi-resistant Pseudomonas aeruginosa and majors in producing ESBLs. In order to reduce the drug resistance strains produce and control the infections of hospital, antibiotics should be used reasonably according to the resulst of drug susceptibility tests and the circumstances of enzyme-producing.Mechanism of imipenem resistance in Pseudomonas aeruginosa AbstractObjective To survey the sensitivities of some commonly used antibiotics against Pseudomonas aeruinosa(PA)and metallo-β-lactamase genes and the out membrane protein OprD2 gene produced by clinical isolated imipenem-resistant P.aeruinosa in our hospital. Methods The minimal inhibitory concentrations (MICs) of 10 sorts of antimicrobial agents against 78 imipenem–resistant clinical isolated strains were determined by agar dilution method;Using disc synergy test to screen metallo-β-lactamase positive strains from imipenem-resistant P.aeruginosa. PCR method was used to detect gene of metallo-β-lactamases and outer membrane protein D2 (OprD2) gene. Results 4 strains of P.aeruginosa producing metallo-β-lactamase were detected to by disc synergy test. The result of PCR exhibited that VIM-2 gene was detected in 4 strians of P.aeruginosa which the phenotype of MBL was positive. All 80 imipenem-resistant P. aeruginosa strains were negative for IMP gene,SPM gene and VIM-1 gene of metallo-β-lactamases; and 4 strains of P.aeruginosa were detected to produce metallo-β-lactamase which was in agreement with the result of disc synergy test, and 36 imipenem-resistant P.aeruginosa strains were negative for OprD2 gene. Conclusions Imipenem-resistant P.aeruinosa is frequently resistant to clinical antimicrobial agents, the most were multi-drug resistant strains. The loss of OprD2 gene is the main reason for the imipenem resistance of P.aeruginsa in our hospital, Metallo-beta-lactamase-producing is the minor reasons...