Extended-spectrum Beta-lactamases and AmpC Enzymes of Pseudomonas aeruginosa:Their Detection and Resistance Analysis

OBJECTIVE To investigate the prevalence of strains producing extended-spectrum β-lactamases (ESBLs) and AmpC β-lactamases in Pseudomonas aeruginosa,and to supply the laboratory evidence for antibiotic rational application in clinic. METHODS Totally 105 clinical isolates of P. aeruginosa were identified with VITEK-32. Drug sensitivities were determined by Kirby-Bauer methods. ESBLs were detected by double-disc synergy test,and cefoxitin three dimensional test was applied to filter AmpC positive strains. RESULTS Among 105 strains of P. aeruginosa,28 strains (26.7%) were AmpC enzymes positive,20 strains (19.0%) were ESBLs positive,and 5 strains(4.8%)were AmpC+ESBLs positive. The detective rate of producing AmpC β-lactamases strains was higher than that of producing ESBLs strains. There was significant difference between them. CONCLUSIONS ESBLs and AmpC β-lactamases are two main enzyme types conferring resistance to β-lactam antibiotics in clinical isolates of P. aeruginosa. Imipenem can be the first choice for treating infections caused by P. aeruginosa producing ESBLs or AmpC β-lactamases.