Emergence of NDM-1, a new metallo-Beta-Lactamase enzyme Carrying Enterobacteriaceae
Globally rising trend of antibiotic resistance is a major concern. Multi drug resistant Gram-negative bacteria are now creating greatest risk to public health. Major mechanism of resistance against Beta lactam antibiotic is enzymatic hydrolysis by Betalactam enzymes. After the dissemination of extended spectrum β lactamase producing enterobacteriaceae, Carbapenem antibiotics including imipenem, meropenem and ertapenem have become drug of first choice for the treatment of infections caused by these bacteria. So far carbapenem resistance is infrequently reported. Main threat with infection caused by carbapnem resistant bacteria are difficulty in selection of antimicrobial therapy, Increased mortality and morbidity, Increased length of hospitalization and Toxicity and costs with therapeutic alternatives
Origin and spread
Carbapenem hydrolyzing enzymes that are reported so far are KPC, VIM metallo-β-lactamase, OXA-48. Recently a novel metallo-β-lactamase enzyme NDM-1 has emerged in members of enterobacteriaceaefamily. The NDM-1 enzyme was named after New Delhi, the capital city of India, as it was first described by Yong et al. in December 2009 in a Swedish national who fell ill with an antibiotic-resistant bacterial infection that he acquired in India. The infection was unsuccessfully treated in a New Delhi hospital and after the patient’s repatriation to Sweden; a carbapenem-resistant Klebsiella pneumoniae strain bearing the novel gene was identified. In March 2010 a study in a hospital in Mumbai found that the majority of carbapenem-resistant bacteria isolated from patients carried the blaNDM-1 gene.
In September 2010, study was published in Lancet Infectious diseases, identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries. That study interpreted that NDM-1 spread is great public health problem, and co-ordinated international surveillance is needed.
List of countries reported NDM-1 linked with India & Pakistan
UK , Canada , USA, Belgium, Sweden, Norway, Netherlands, France, Germany, Austria, Singapore, Japan, Taiwan, Hong Kong, Oman, Australia, Kenya