Acinetobacter species are among the most common nosocomial pathogens that are notorious for multi-drug resistance. Their immense ability to acquire or upregulate antibiotic drug resistance determinants has established them as a successful pathogen, causing wide range of infections such as wound infection, respiratory tract infection, urinary tract infection, bacteraemia, pneumonia, meningitis etc. which seriously challenges the treatment of immunocompromised individuals. Recent emergence of acquired Metallo-β-lactamases (MBLS) among them has added additional burden to our therapeutic option.
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 Ethylene Diamine Tetra Acetate (EDTA) as well as other chelating agents of divalent cations is the quintessential features of MBLs that correlates with their mechanistic function(2). 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 MBLs 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 (3).
Since MBLs confers a high level of resistance to antimicrobial agents from different antimicrobial categories, early detection of such strains will avoid potential risks of therapeutic failure in patients as well as timely implementation of appropriate infection control measures to prevent future dissemination. This research was carried out by using non-molecular method of Imipenem-EDTA combined disk method at Shree Birendra Hospital (Army Hospital) in Kathmandu, Nepal.