Distribution of Extended-spectrum β-lactamase and Metallo-β-lactamase-producing Pseudomonas aeruginosa in Tertiary Care Hospitals of Lahore, Pakistan

Background: Pseudomonas aeruginosa (P. aeruginosa) is an important bacterial pathogen most frequently associated with nosocomial infections, especially in immuno-compromised patients. Early detection of these life threatening, β-lactamase producing bacteria is essential for infection control and to prevent their dissemination. The aim of our study was to detect the presence of Extended-Spectrum β-Lactamase (ESBL) and Metallo-β-Lactamase (MBL) strains of Pseudomonas aeruginosa.Material and Methods: Eighty-eight identified strains of P. aeruginosa were collected from Chughtai Laboratories, Combined Military Hospital and Children Hospital, Lahore. These strains were sub-cultured and after confirming the cultural characteristics by Gram staining and colony morphology, manual biochemical identification was done. Susceptibility to various antibiotics and production of extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) were determined using modified Kirby Bauer disk diffusion method, double disk synergy test, combined disk synergy test (CDST) and inhibitor-potentiated disk diffusion test (IPD) respectively.Results: Out of eighty-eight strains tested, three were ESBL producers (3.4%) and eleven strains (12.5%) were found to be resistant to carbapenems. Of these, eight were MBL producers (72.7%). All these β-lactamase producing strains (14 strains) were multidrug-resistant (MDR). Piperacillin and piperacillin/tazobactam proved to be the most effective antibiotics in both types of β-lactamase producing strains.Conclusion: Our study shows noticeable emergence of β-lactamases (ESBLs & MBLs) in P. aeruginosa. All of these strains were MDR. It reveals a correlation of these β-lactamases with multidrug resistant genes