screening for metallo-β-lactamase producing pseudomonas aeruginosa in clinical isolates in a tertiary care hospital in north india

Introduction: Pseudomonas aeruginosa has acquired a new metallo-β-lactamase (MBL) resistance gene responsible for increased resistance to fluoroquinolones, cephalosporins and carbapenems. Thus, it is essential to know the antibiotic sensitivity pattern and follow the antibiotic policy. Objectives: The objective of this study is to detect MBL production in clinical isolates by combined imipenem-ethylenediamine tetra acetic acid (IMP-EDTA) disc test. Materials and Methods: This study was conducted for a period of nine months from April 2011 to December 2011. A total of 66 consecutive isolates of P. aeruginosa were subjected to susceptibility testing by disc diffusion assay. IMP drug resistant strains were screened for MBL production by combined IMP-EDTA disc test. Results: Ciprofloxacin resistance was seen in 66.6% isolates followed by piperacillin in 51.5%. Resistance toward amikacin, ceftazidime, and cefoperazone were noted in 43.9%, 40.9%, and 37.8% isolates, respectively. In 37.8%, IMP resistance was observed. All IMP resistant strains (n = 25) were screened for MBL production. All the 25 isolates (100%) were MBL producers, exhibiting more than 7 mm zone size enhancement in IMP-EDTA combined disc test. Conclusion: Emergence of P. aeruginosa as MBL producer is becoming a therapeutic challenge. There is a need to implement routine antibiotic surveillance and judicious use of antibiotics.