So, we thought the worse was over; we thought we are done fighting the bad guys, HIV, SARS and H1N1A, but now it seems that a new menace is eminent. Our chaotic and rather foolish use of antibiotics have created this unknown danger that could add a new chapter to the history of medicine and fighting infectious diseases. This danger is called New Delhi metallo Beta-Lactamase -1, AKA NDM-1
Meet the Bug
In December 2009, a super villain appeared on the scene; he’s violent, resistant and determined to do as much damage as he could. Our super villain is the NDM-1 (New Delhi metallo beta lactamase – 1), a newly emerging beta-lactam resistance enzyme including carbapenems, which are one of few alternatives used for antibiotic-resistant bacterial infections. The NDM-1 gene is classified as a Carbapenemases . The enzyme is named after the city in which it first appeared, New Delhi, the Indian capital. In December 2009, a Swedish patient in India acquired an antibiotic resistant infection. Being unsuccessfully treated in India, the patient was further transferred to Sweden. The carbapenem-resistant Klebsiella pneumoniae was identified carrying the novel NDM-1 gene. A later study in India found that carbapenem-resistant strains from patients in India carried the NDM-1.
In May 2010, an E. coli expressing the NDM-1 gene was isolated from a patient in the UK, the patient was of Indian origin and had visited India 18 months ago where he had been undergoing dialysis. According to CDC Morbidity and Mortality Weekly Report (MMWR) , as of June 2010, three Enterobacteriaceae isolates carrying the NDM-1 gene were discovered in the U.S., which were E. coli, Klebsiella pneumoniae, and Enterobacter cloacae, NDM-1 provided the three isolates with resistance to all antibiotics except for Aztreonam. Fortunately to the bacteria but unfortunately to our patient, the isolates conferred resistance even to Aztreonam by different mechanism other than the NDM-1, and the MMWR established that all the three U.S. isolates were related to patients who had medical care in India.
Furthermore, a team in India in July 2010, reported cases of Acinetobacter baumannii carrying the NDM-1 in India. A recent study by a multinational team published in “The Lancet Infectious Diseases, September 2010” reported that the isolation of 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 E. coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics. Luckily, all the studies have confirmed that all NDM-1 isolates were susceptible to the antibiotics tigecycline (the FDA-approved glycylcycline antibiotic developed by Francis Tally and marketed by Wyeth under the brand name Tygacil®), and colistin (polymyxin E antibiotic, which causes nephrotoxicity and neurotoxicity at high dose IV). Some unconfirmed reports indicate the NDM-1 appearing in Canada and Japan earlier this month (Sep 2010).
In June 2010, patient zero –the first reported death– was a Belgian man who had a car accident in Pakistan, first being treated in a hospital in Pakistan and he became infected with the Bug carrying the NDM-1. He was further transferred to Belgium where he was hospitalized with major leg injury, and despite being administered colistin, the patient died!
We now face a new challenge. Could this superbug mean the end of the beta-lactam antibiotics era?!
- The Boston Globe: Superbug patient treated at mgh
- Google News: Belgian man dies of a superbug
Image credit:bacterial resistance, betalactams, escherichia coli, klebsiella pneumoniae, NDM-1, resistant strains, Superbug