Drug resistant bug review: NDM-1 in New Delhi’s sewage, WHO calls to action, recent outbreaks of antibiotic resistant bacteria

http://healthmap.org/resistance

Last summer, media around the world reported on a newly discovered gene that provides bacteria the ability to evade almost all antibiotics (see our August 2010 blog). Researchers named it NDM-1 after New Delhi because it was thought to have originated there. Antibiotic resistant bacteria are often associated with hospital acquired infections; the frequent use of antibiotics in healthcare settings can enhance the development of resistance. Local politicians in New Delhi were outraged at the perceived smear of their city and denied that New Delhi was the source. Some of them also noted that many of the reported European cases had not been in hospital or at a clinic while in India.

The Lancet Infectious Diseases has now published online a study which examined 171 sewage samples and 50 water samples from throughout New Delhi. Samples from Cardiff, Wales were also evaluated as a control. None of the Welsh samples produced bacteria with the NDM-1 resistance gene. Among the New Delhi samples, however, 51 of the sewage and 2 of the water samples grew NDM-1 bacteria. The implications are important. Bacteria with the NDM-1 resistance gene appear to be not only widespread in New Delhi’s sewage but also present in some water samples, potentially explaining cases among Europeans who had travelled to India but had not sought medical treatment while there. A week after the study’s publication, India’s National Centre for Disease Control stated they would perform their own study on the presence of antibiotic resistant bacteria.

This past World Health Day (April 7th), the World Health Organization called on nations to fight antibiotic resistance. The WHO statement notes: “The world is on the brink of losing these miracle cures. . . . the R&D pipeline for new antimicrobials has practically run dry.” The threat of resistance is as old as the drugs themselves. During his 1945 Nobel Prize acceptance speech, penicillin discoverer Alexander Fleming warned of the risk of penicillin-resistance in bacteria if inadequate doses were used. Failure to complete a course of antibiotics may leave some bacteria weakened but not dead. The surviving bacteria can then produce entire populations of bacteria which are resistant to that drug.

Today, the problem of resistance is complex. In many countries, antibiotics are taken without a prescription (53% of Indians do so). Antibiotics in sewage (present either by flushing unused pills down the toilet or by excreting trace amounts of antibiotics through regular biologic function) also promote resistance by exposing bacteria to low levels of these drugs. People living in poverty (in both developing and developed nations) may take enough pills to feel better and then save the rest for future use, a false but understandable economy. Sometimes disasters or changes in international funding disrupt the supply of drugs to those who are on long-term antimicrobial medications. For example, a new case of tuberculosis is often treated for six months. If disaster, civil war, or manufacturing delays interrupt a patient’s treatment, he is not only at risk for a relapse, he is also more likely to develop drug resistant tuberculosis. Additionally, few new antibiotics are being researched, both because it is hard and because other medications are far more profitable.

A review of outbreaks recently mapped by HealthMap shows MRSA (Methicillin-Resistant Staphylococcus aureus) outbreaks in a UK hospital and a Chicago school. Over 350 cases of CRKP (Carbapenem-Resistant Klebsiella pneumoniae) were reported in Los Angeles County nursing homes, while a hospital in Ireland also saw cases of CRKP. A Scottish hospital has been battling VRE (Vancomycin-Resistant Enterovirus). Antiviral resistance is also a problem; Delaware reported 4 cases of Tamiflu-resistant influenza in March.  

Antibiotic resistance is a growing problem that will require international efforts and extensive patient cooperation to combat. For more information on antibiotic resistance, check out the CDC’s or the WHO’s web pages on the topic.  To see outbreaks of antibiotic resistant infections since the identification of NDM-1 last August, go to http://healthmap.org/resistance.