The production of Metallo-β-lactamase is one of the resistance mechanisms of Pseudomonas aeruginosa. Metallo-β- lactamases are members of Group B in the molecular classification of Ambler and are Clavulanic acid resistant enzymes which require divalent cations of zinc as co-factors for enzymatic activity(1). Characteristic features of being universally inhibited by ethylenediamine tetra acetic acid (EDTA) as well as other chelating agents of divalent cations is the quintessential features of MBLs that correlates with their mechanistic function(2).
Carbapenems are class of β-lactam antibiotics with a broad spectrum of antibacterial activity is one of the last resorts for the treatment of multi drug resistance microbes but due to the emergence of New Delhi metallo-beta-lactamase (blaNDM-1) which confers resistance to carbapenems has brought therapeutic dilemma to clinicians as well as challenge to Microbiologist throughout the world (3). There are several non-molecular methods that have been tried using the property of enzyme’s zinc dependence by using various chelating agents for the detection of MBL production but the double disc synergy test using a Ceftazidime disc and 2-mercaptopropionic acid disk or an Imipenem disc and an EDTA disc have been reported to be simple methods (4).
This research was carried out by using non-molecular method of Imipenem disc and EDTA combination by me along with Kamal Bagale from Centre Department of Microbiology, Tribhuvan University at Shree Birendra Hospital (Army Hospital) in Kathmandu, Nepal.