Prevalence of Metallo-β-Lactamase producing Pseudomonas aeruginosa in wound infections in Duhok city, Iraq

Najim A. Yassin, Haval M. Khalid, Ayman O. Hassan


Background: Pseudomonas aeruginosa is common pathogen causing nosocomial infection. Acquired drug resistance and Metallo-β-lactamases (MBL) production have recently emerged as one of the most worrisome resistance mechanism that hydrolyze all beta-lactam antibiotics including penicillins, cephalosporins and carbapenems, with the exception of aztreonam. The aim was to find out the prevalence of multi drug resistant (MDR) and Metallo-β-lactamase (MBL) positive isolates of P. aeruginosa in wounds samples which are a serious concern.

Methods: Pseudomonas aeruginosa strains were obtained by standard isolation and identification techniques from 307 wound samples of hospital. Strains were then subjected to susceptibility testing for anti-pseudomonas drugs as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Carbapenems resistant strains were selected for the detection of MBL enzyme production by disc potentiation test. Production of MBL was confirmed by enhancement of inhibition zone around imipenem and meropenem discs impregnated with EDTA, as compared to discs without EDTA.

Results: Amongst the 71 isolates of P. aeruginosa, 62(87.3%) isolate were imipenem-sensitive, while 9(12.7%) isolates were found to be imipenem resistant and MBL producers. Very high resistance to antibiotics was recorded amongst MBL producers’ P. aeruginosa compared with non-MBL imipenem-sensitive strains.

Conclusion: Study indicates that, surveillance for the detection of MBL is necessary. The rapid dissemination of MBL producers is worrisome and necessitates the implementation of proper and judicious selection of antibiotics especially carbapenem.



Metallo-beta (β)-lactamase, Pseudomonas aeruginosa, Imipenem, EDTA

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