A preliminary study on metallo-beta-lactamase producing Pseudomonas aeruginosa in hospitalized patients

Metallo beta-lactamase (MBL) producing Pseudomonas aeruginosa is an emerging threat and a cause of concern for the physicians treating such infections. The present study was undertaken to know the resistance pattern of P. aeruginosa to beta-lactamase inhibitors and carbapenems, and to detect the presence of MBL among resistant isolates to both groups of antibiotics. Between June-November 2001, 50 P. aeruginosa isolates from clinical specimens were tested for susceptibility to beta-lactamase inhibitors and carbapenems by Kirby-Bauer disc diffusion method. Isolates resistant to both groups of antibiotics were screened for the presence of MBLs by disc diffusion method using 2-mercaptoethanol. Of the 50 isolates, 6 (12%) were resistant to both beta-lactamase inhibitors and carbapenems. All 6 isolates were MBL producers were resistant to all the antibiotics tested. Resistance to piperacillin-tazobactam, cefoperazone-sulbactam and ticarcillin-clavulanic acid was 12, 20 and 36 per cent respectively. Resistance of 12 per cent each was noted to imipenem and meropenem respectively. This is to the best of our knowledge the first report of MBL producing P. aeruginosa from India and suggests the need for early detection, notification and control of spread.