Outer Membrane Protein and ?-Lactamases in Imipenem Resistant Pseudomonas aeruginosa / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To investigate the mechanisms for carbapenem resistance in clinical isolates of Pseudomonas aeruginosa from surgical intensive care unit(SICU).METHODS The minimal inhibitory concentrations(MICs) of various antibiotics were detected with agar dilution method;their ?-lactamases were extracted,types of their enzymes were identified and then their physical and chemical characteristics were studied by three dimentional extract test and isoelectric focusing(IEF) electropheresis;primers specific to IMP and VIM genes were utilized to amplify the metallo-?-lactamase genes.The levels of outer membrane protein OprD2 were measured by Western blot.RESULTS Forty one strains were resistant to imipenem from 49 strains of P.aeruginosa isolated from SICU during 3 years.Among them,34 isolates were found to produce high level of AmpC enzymes.Eight produced extended-spectrum ?-lactamases(ESBLs) at the same time.2 produced ESBLs only.No metallo-?-lactamases were detected.The activity of enzymes in the imipenem resistant group(74.32?53.42) was statistically different from the sensitive one(8.7?16.16,P