OCCURRENCE AND DETECTION OF EXTENDED SPECTRUM β-LACTAMASE AND AmpC β-LACTAMASE IN CLINICAL ISOLATES OF Pseudomonas aeruginosa AND Acinetobacter baumanii BY INHIBITOR BASED METHOD

Pseudomonsa aeruginosa and Acinetobacter baumannii are common non-fermenters which have emerged as the most common opportunistic pathogens in recent years. Persistent exposure of Pseudomonas aeruginosa and Acinetobacter baumanii to beta -lactam antibiotics leads to acquired resistance through mutation and over production of various enzymes which also include AmpC or class C beta -lactamases and extended spectrum beta -lactamase (ESBL). For clinical microbiologists, detection of ESBL and AmpC-mediated resistance together poses a problem because the phenotypic tests may be misleading; resulting in misreporting and treatment failures. A total number of 94 consecutive, non-repetitive, imipenem sensitve clinical isolates of Pseudomonas aeruginosa (n=64) and Acinetobacter baumannii (n=30) obtained over a period of 6 months, were screened for beta -lactamase production by nitrocefin disc and production of ESBL and AmpC beta -lactamase is detected by Inhibitor based test. A total of 50 out of 94 isolates were positive for beta -lactamase production; of which 17 (15.98%) and 22 (20.68%) were ESBL and AmpC beta -lactamase producers respectively.