The Analysis Of The Infections And Drug Resistance Of 53 Pseudomonas Aeruginosa

1. BackgroundPseudomonas aeruginosa,also called "pseudomonas pyocyanea",is a common pathogen of nosocomial infection .It can be found in natural enviroment,skin of human body, respiratory tract, intestinal tract and medical instrumentations.It is an important opportunistic nosocomial pathogen and particularly important in hospital acquired pneumoniae,especially in immune-compromised patients and those with tracheal cannula,tracheotomy or mechanical ventilation.With the drug resistance by different mechanisms,it often caused the failure of the clinical treatment.However, the situations of resistance caused by P.aeruginosa become more serious as -lactams, immuno-suppressive drugs and anti-neoplasm drugs are used widely in clinical oractice.Mechanisms of P.aeruginosa drug resistance includerproduction of -lactamases;imipenem resistant by the loss of outer membran porin OprD2;active efflux pumps in outer membran;productions of aminoglycoside-modifying enzymes; the change of target positions;biofilm formation.The production of -lactamases is the main reasoncaused the (3-lactams resistance. The (3-lactamases emerged such as ESBLs. plasmid-induced AmpC,cabapenemases with the new p-lactams in practice.We carried out this study to demonstrate the resistance pattern,the types of P-lactamases and drug resistance of P.aeruginosa. Meanwhile.analyze the cases by-retrospective studies. 2.Materials and methodsThe 53 P.aeruginosa collected from clinical specimens in the Fisrt Affliated Hospital,College of Medicine, Zhejiang University from July to December in 2003. .Antimicrobial activity to the strains were determined by K-B test;extract the p-lactamases by ultrasound; (3-lactamases produced by these strains were characterized by three-dimensional test;SPSS10.0 analyze the data. 3.ResuItsThe most active agents against these strains were cefepime and meropenem with the susceptibility rate of 79.2%;cefoperazone/sulbactam,ceftazidime,amikacin,imipenem,ti-carcillin/clavulanic acid with the susceptibility rate above 70%.The intermediate and resistance rate of quinolones(ciprofloxacin, Levofloxacin,moxifloxin),monobactam(aztreo-nam) and cephamycin(latamoxef) is 35.8-77.4%.Three-dimensional test detected 8 strains with production of carbapenemases and 6 strains with AmpC,l strain probably both ESBLs and AmpC.With SPSS 10.0 to analyze the lactamase-producing strains between non lactainase-producing strains,we found the notable significance in 11 drugs.4.conclusion(1).The infections caused by P.aeruginosa in hospital usually occurred in respiratory-tract.(2).These strains were resistant to quinolones,monobactam and cephamycin;but more susceptible to cefepime and meropenem which can be used in clinical treatment.(3).The main types of 3-lactamases produced by the strains were carbapenemases and AmpC.