Prevalence of blaNDM-1 Producing Blood Isolates of Escherichia Coli, Klebsiella species and Enterobacter Species in a Tertiary Care Centre in South India

Carbapenems like meropenem and imipenem are being increasingly used for the treatment of multidrug resistant pathogens especially those producing extended spectrum beta lactamase and AmpC beta lactamase. Since the first usage of antibiotics, the burden of resistance has progressively increased over the past several years. Carbapenemases are the enzymes which are capable of hydrolyzing carbapenems and are a heterogeneous mixture of beta lactamases belonging to Ambler molecular class A (Penicillinases), class B (Metallo enzymes) and class D (oxacillinases). Carbapenem-resistant Enterobacteriaceae (CRE) due to carbapenemase production is being increasingly seen in clinical practice and has been reported worldwide over the past few years. This jeopardizes the effective use of carbapenems and have led to the development of `superbugs`. Blood stream infections caused by these CRE are important cause of morbidity and mortality. In the present study, we investigated the prevalence of blaNDM-1 producing blood isolates of Escherichia coli, Klebsiella species and Enterobacter species. All the 93 blood isolates of Escherichia coli, Klebsiella species and Enterobacter species collected from October 2010 to March 2012 were either resistant to or intermediate to meropenem by disc diffusion method. Minimum inhibitory concentration determination of meropenem for all these isolates showed varied results. The results of phenotypic and genotypic tests for the presence of carbapenemases showed a prevalence of 70.6% of bla NDM-1 among the study isolates. 67% of bla NDM-1 was found in Klebsiella species, 75% in Escherichia coli and 76 % in Enterobacter species. The indiscriminate and inappropriate use of antibiotics has led to the development of these multi drug resistant pathogens. As there are no antibiotics currently available for the treatment of these organisms, judicial use of antibiotics should be practiced and strict antibiotic policy and hospital infection surveillance should be implemented for halting further spread of these organisms.