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

Abstract

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.

Detection of New Delhi metallo-beta-lactamase enzyme gene bla NDM-1 associated with the Int-1 gene in Gram-negative bacteria collected from the effluent treatment plant of a tuberculosis care hospital in Delhi, India

“…NDM-1, 2, 3, 4 [14][15][16]) and the genes encoding them (bla NDM-1, 2, 3 ). Bacterial strains which are positive for bla NDM (genotypic resistance marker gene) and also produce NDM enzymes are particularly dangerous because, (1) There is no routine standard phenotypic test for MBL detection; (2) Consequently there is a possibility of high prevalence of unrecognized asymptomatic carriers amongst general population; (3) There is lack of effective antibiotics against NDM-1-positive superbugs; and (4) Plasmids from these bacteria can undergo wide rearrangement and thus can cause widespread horizontal transmission of the antibiotic resistance gene (bla NDM-1 ) [17][18][19][20].…”