Prevalence of metalo- β-lactamase-producing (MBL) Acinetobacter species in a tertiary care hospital

BACKGROUND AND OBJECTIVES Acinetobacter causes a wide variety of illness in debilitated and hospitalized patients. Carbapenem resistance in Acinetobacter is an emerging problem and is a cause of concern as many nosocomial infections with Acinetobacter are resistant to most other antibiotics. The present study was aimed to study metallo-β-lactamase (MBL) production in Acinetobacter species. MATERIALS AND METHODS During one year prospective study, all isolates of Acinetobacter obtained from various clinical samples like respiratory, pus, blood and others were included. Antimicrobial susceptibility testing was done by standard Kirby Bauer disk diffusion method. Metallo β-lactamase (MBL) detection was done by imipenem-EDTA combined disk method. RESULTS Among 1017 isolates, 964 were A. baumannii, 48 were A. lwoffii and 5 were A. hemolyticus. Out of these, majority of the isolates were obtained from respiratory samples, followed by pus. A .baumannii showed high level of resistance to cephalosporins, cotrimoxazole and piperacillin. A .lwoffii and A. hemolyticus showed lesser resistance to all antibiotics. Imipenem resistance was observed in 389 (40.3 %) isolates of A.baumannii and MBL activity was seen in 80.3% of isolates. MBL positive isolates of A. baumannii showed higher resistance as compared to MBL negative isolates. CONCLUSION This study demonstrated that multidrug resistant strains of Acinetobacter are common in tertiary care hospitals. Unwarranted and unrestricted usage of antibiotics is associated with emergence of resistance in nosocomial pathogens. Regular monitoring and documentation of carbapenem resistant is crucial in developing strategies to control infection due to these bacteria.