Bacteria with the New Delhi metallo-betalactamase or NDM enzyme remain susceptible to only one antibiotic known as colistin with only limited susceptibility to three others, a study by Public Health England (PHE) has found.
This means that infections caused by bacteria with this mechanism are very hard to treat. The study, published online in the Journal of Antimicrobial Chemotherapy, reports on one of the largest collections of NDM isolates outside of the Indian subcontinent and analysed 326 bacterial isolates from 250 patients collected over five-and-a-half years.
Most NDM-positive bacteria were resistant to all the carbapenem antibiotics tested. These are viewed as antibiotics of ‘last resort’ and limiting the spread of carbapenem-resistant bacteria is of paramount importance. NDM-1 is one of a number of different enzymes (carbapenemases), which can destroy these important medicines making bacteria resistant to most ‘penicillin-like’ antibiotics.
Another key group of antibiotics in clinical use are called aminoglycosides. But PHE’s results showed that 234 of 306 (76%) of NDMpositive bacteria were also resistant to the three aminoglycosides tested (amikacin, gentamicin and tobramycin). However, about 90% of the isolates were susceptible to colistin.
Professor Anthony Kessel, director of public health strategy at PHE, said: “The results of this study are a stark reminder of the issue that we are facing with the growing problem of antibiotic resistance.”
