New Delhi Metallo-beta lactamase-1 containing enterobacteriaceae: origin, diagnosis, treatment and public health concern.

One of the biggest problems associated with the antibiotic therapy is resistance. Recently published studies have revealed that enterobacteriaceae, like E. coli and Klebsiella, isolated from several Indian centers are resistant to many antibiotics including some highly potent antibiotics like carbapenems. It has been proposed that this resistance is because of a carbapenemase enzyme called NDM-1 (New Delhi Metallo-betalactamase-1). This carbapenemase is class B carbapenemase also called metallolactamases as they require zinc at their active site. This enzyme is coded by a gene called bla-NDM-1 or gene NDM-1. NDM-1 containing enterobacteriaceae can be screened in laboratory by few techniques. Metallolactamase production can be detected by disk approximation test or Modified Hodge test and NDM-1 gene can be detected by polymerase chain reaction by the use of specific primer targeting the gene. Infections caused by such bacteria are associated with high morbidity and mortality. Two classes of antibiotics i.e., polymyxins (colistin) and glycylcyclines (tigecyclines), have shown in vitro activity against NDM-1 harboring enterobacteriaceae. The safety profile of both of these antibiotics is questionable. There is a need for active screening of microorganisms for NDM-1 and research should be directed towards the development of safe antibiotics for the treatment of these kinds of infections.