Antimicrobial Resistance of Pseudomonas aeruginosa and Detection of Its Metallo-β-lactamases

OBJECTIVE To investigate antimicrobial resistance of Pseudomonas aeruginosa and detect metallo-β-lactamases(MBLs)in clinic.METHODS Ninety-five strains of P.aeruginosa were isolated from sputum samples during the period from Jul 2005 to Aug 2008 in the affiliated hospital of North Sichuan Medical College.Bacteria identification and antimicrobial susceptibility test(to 18 antibiotics)were performed by VITEK-32 system and NC21,The K-B method was applied to affirm the susceptibility to imipenem,meropenem,cefoperazone/sulbactam and polymyxin E of the 30 strains with antimicrobial resistance to imipenem confirmed by instrument.The Etest method was utilized to detect the MBLs of 19 strains with antimicrobial resistance to imipenem confirmed by the K-B method.RESULTS The antimicrobial resistance rates of the 95 strains display that the lowest rate was amikacin which was 15.4%,the other antbiotic′s resistance rates fluctuateed from 26.7% to 100.0%;in the 30 strains with antimicrobial resistance to imipenem confirmed by instrument,there was no remarkable difference between the imipenem and meropenem(u 1.04,P0.05),the susceptibility of cefoperazone/sulbactam was higher than the imipenem(u 2.6,P0.05),the susceptibility of polymyxin was also higher than the imipenem(u 527.5,P0.05).Twelve strins generating MBLs were screened from 19 strins with imipenem resistance confirmed by K-B,and the positive rate was 63.2%.CONCLUSIONS The multidrug resistance of P.aeruginosa which isolated from our clinical specimens is a serious issue.The producing rate MBLs within the imipenem resistance strains is higher;there should be effiective if using the polymyxin B or cefoperazone/sulbactam to treat the imipenem resistance P.aeruginosa.MBLs producing P.aeruginosa has a trend to prevail intermittently in the hospital.