This post appeared on January 19 on the blog End the Neglect, which deals with neglected tropical diseases, and which I promise I will stop neglecting: TDR-TB and the NTDS. It points to even more disturbing implications of total drug resistance. Excerpt:
Last week, the existence of a new form of TB hit the media. This new type, currently called totally drug resistant tuberculosis, or TDR-TB, is exactly what it sounds like. Doctors have not yet been able to identify a treatment for this TB that will work. As far as we can tell, it is resistant to all existing regimens. The WHO is looking into it, but this is a bad, bad, development for global health.
So what does this have to do with neglected tropical diseases (NTDs)?
Well, many NTDs are bacterial, which means they are treated with antibiotics, just like the treatment for TB. This means that they’re as much at risk for antibacterial resistance as TB is. In addition, TB has benefited from research, and the development of newer drugs. There has been less research into finding new treatments for NTDs.
Trachoma, a bacterial infection that leads to blindness, has been controlled or eliminated in many countries through the use of the antibiotic azithromycin. Azithromycin is used extensively for everything from traveler’s diarrhea to STIs to pertussis, and in many countries it’s available over the counter. That’s pretty much a recipe for antibacterial resistance. Treatment for Leptospirosis, a bacterial disease that affects humans and animals, also depends on azithromycin.
Leprosy (aka Hansen’s disease) is another NTD dependent on antibiotic treatment. Mycobacterium leprae, the bacteria that causes leprosy, responds well to Dapsone, Rifampin, and Clofazimine. Dapsone is one of the very oldest antibiotics, dating to the 1930s. In addition to treating leprosy, it’s a second-line TB drug.
Rifampicin was created in 1959, and it’s commonly used as one drug in combination therapy for tuberculosis. (If you’re noticing a trend here, there’s a reason. Both Tuberculosis and leprosy are caused by mycobacteria, so they respond to similar drugs.)
If it’s not used strictly in combination with other antibiotics, resistance to rifampin builds very quickly. This is a problem, since rifampin is also effective against chlamydia and gonorrhea, and therefore tends to be a hot property among people who are secretly self-treating. Clofazimine was first synthesized in 1954. It’s not used for much beyond leprosy. It has brutal side effects, and it doesn’t work on TB.
So, if the TB drugs are beginning to see resistance – total resistance – it’s very likely we could see resistance in the antibiotics used for the NTDs as well.
