NDM-1 is a gene known as “New Delhi metallo-beta-lactamase-1”, which gives certain kind of bacteria the ability to produce an enzyme called carbapenemase that renders resistance to broad range of β-lactum antibiotics. These include the antibiotics of Carbapenem family, also known as antibiotics of last resort, along with Penicillin and Cephalosporin.
NDM-1 was first identified in a Klebsiella pneumoniea isolated from a Swedish patient of Indian origin in 2008, however there is still a debate going on regarding the exact year in which NDM-1 was first reported. After extensive survey, sources say that NDM-1 was also detected in Pakistan, United Kingdom, United States, Canada, Japan and Brazil. The similarity among all these detections was that all the patients in whom NDM-1 was detected were exposed to treatment in India for some diseases in their past. “New Delhi metallo-beta-lactamase” was first described by Young et al. in December 2009 in a Swedish national who fell ill with an antibiotic resistant bacterial infection that he acquired in India…
A study published in the journal, ‘The Lancet Infectious Disease’, in August 2010 found the presence of a new gene called NDM-1 or New Delhi metallo-beta-lactamase that gives certain kinds of bacteria the ability to produce an enzyme carbapenemase that renders many antibiotics useless. But later on Jan 12th 2011, the editor of Britain’s prestigious medical journal ‘The Lancet’ has apologized for erroneously naming a drug resistant superbug after national capital New Delhi that sullied the reputation of the country.
Formerly NDM-1 was considered to be hospital acquired resistance as most of the individual patients had direct links to Indian hospitals, having been treated for various diseases. But later on it was found that it was community acquired and brought into hospitals.
Mechanism:
NDM-1 is a gene produced by certain gram-negative strains that have recently acquired the genetic ability to make the carbapenemase enzyme. Most of the antibiotics have a β-lactum ring which plays a major role in eradicating gram-negative infectious bacteria. Many antibiotics like Cephalosporins, Penicillins and Carbapenems have this ring in their chemical structure. The β-lactum ring inhibits the synthesis of peptidoglycon in the formation of protective outer membrane of bacterial strains which is responsible for pathogenicity.
The gene NDM-1 is known as blaNDM-1. This gene encodes for Carbapenemase enzyme which hydrolyzes the β-lactum ring and suppresses its action. The strains that produce this enzyme are often referred as “Superbugs”. Due to the presence of blaNDM-1 gene in such strains, they are extensively resistant to β-lactum antibiotics: Penicillins, Cephalosporins, and Carbapenems which are a mainstay for the treatment of antibiotic resistant bacterial infections.
Unfortunately the presence of blaNDM-1 gene insists acquiring of resistance to other drugs also. Hence, treating such infections caused by superbugs is difficult. But such strains have been found susceptible only to Polymyxin, colistin and Tigecyclin.
Recent findings say that blaNDM-1 gene can spread from one strain of bacteria to another by Horizontal Gene Transfer which is defined as the movement of genetic material between bacteria other than one of its offspring by descend in which information travels through the generations as the cell divides. blaNDM-1 gene has been identified on bacterial chromosomes and plasmids. As plasmids act as a vector for gene transfer, these highly resistant bacteria could support more antibiotic-sensitive strains. In this way, the ability to produce NDM-1 can pass from one bacterial strain to another and even from one bacterial genus to another.
According to a survey; at least 5 lakh people have these bacteria as their normal gastrointestinal flora and are healthy however when the individual is exposed to any infection, the antibiotics do not work because of the presence of these bacteria. Hence it can be considered as a hidden disorder. Maintaining perfect hand hygiene and proper hospital disinfection can prevent the infection of such bacteria. WHO has issued a statement saying, “No action today, No cure tomorrow”. These are wise words and should be taken very seriously.
