Metallo Beta-Lactamase Resistance Mechanisms among Multi-Drug Resistant Pseudomonas aeruginosa (MDRPA)

Background: Pseudomonas aeruginosa is one of the most important pathogens causing nosocomial infections, it is naturally resistant to many antimicrobial agents. It has a distinctive capacity to become resistant to many available antimicrobial agents via multiple mechanisms. One of the major clinical problems regarding Pseudomonas aeruginosa is attributed to the production of Metallo-Beta lactamase (MBL) enzymes. This group of enzymes is members of beta-lactamases which constitute Ambler class B that hydrolyze-carbapenems.

Aim: This study was carried out to find out the predominant resistance mechanisms among Multi-drug Resistant Pseudomonas aeruginosa (MDRPA) and the prevalence of corresponding resistance genes.

Materials and Methods: In this cross-sectional study, MDRPA isolates collected from various clinical samples for a period of one year from March 2015 to February 2016 were included to detect the predominant mechanism of resistance using phenotypic and molecular methods. Molecular characterization of all these isolates was done by Polymerase Chain Reaction (PCR) for the presence of blaVIM2, blaIMP-1, blaOXA-23, and blaNDM-1 genes with specific primers.

Results: Among 120 MDRPA isolates 70 (58.33%) were MBL producers. Molecular characterization studied by PCR showed 15 (12.5%) of vim2 gene and only 2 (1.66%) of IMP 1 gene. None of the 120 MDRPA has produced OXA 23 and NDM gene in our study. MDRPA infections are likely to affect critically ill patients who require prolonged hospitalization. Infections with MDRPA are also associated with adverse clinical outcome. Strict isolation of patients infected with MDRPA and judicial use of antibiotics should be emphasized in order to prevent the spread of MDRPA infections.

Conclusion: The prevalence of MBLs has been increasing worldwide, particularly among P. aeruginosa, leading to severe limitations in the therapeutic options for the management. Thus, proper resistance screening measures and appropriate antibiotic policy can be strictly adopted by all the healthcare facility providers to overcome these superbugs.