Antibacterial activity of carbapenem antibiotics against Pseudomonas aeruginosa

Objective To study the change of sensitivity and resistance of Pseudomonas aeruginosa(PA)isolated from hospital to carbapenem antibitics.To investigate the relationship of the resistance to carbapenem antibitics with the production of AmpC enzyme.Methods PA isolated from our hospital was collected and identified.The strains producing AmpC enzyme were screened initially using sensitivity test of cefoxitin.Antibacterial actity of cephalosporins and carbapenem antibitics to PA was detected by K-B and solid medium serial dilution test.Three-dimensional test was used to detect the production of AmpC enzyme of drug-resistant strains.Results The resistance rates of clinical isolates of PA to CXM,CAZ,CTX,CFP,FEP were 100%,36.3%,63.64%,54.5%,22.7%,respectively.The resistance rates of clinical isolates of PA to IPM,ETP,MEM were 28.64%,26.63%,18.1%,respectively.There was a wide gap between the results of MIC and MBC(MBC was 16-32 times as much as MIC in about 36.0% strains).AmpC enzyme from about 22.6% strains was detected.Conclusion PA has a higher sensitivity to generation 4 of cephalosporins.The sensitivity to MEM is significantly higher than of PA to IPM and ETP,but with a large umber of drug-resistant strains,which may be ralated to the production of AmpC enzyme in some strains.