Extensively Drug-Resistant Tuberculosis: You Can Teach an Old Dog New Tricks

TO THE EDITOR—I read with interest the articles by Cegielski et al and Daley and Horsburgh [1, 2] on extensively drugresistant (XDR) tuberculosis. However, their general tone is too dramatic from my point of view, as it reflects the general idea that only new drugs can be effective for XDR tuberculosis, that not being true. Research on tuberculosis treatment has been focused on tuberculosis only, neglecting drugs efficient for closely related bacteria. As a matter of fact, many “ancient” drugs have not been tested or used to solve current resistance problem [3]. Moreover, as these drugs do not generate high profits, they are neglected by the pharmaceutical industry. As for XDR tuberculosis, I recently proposed to test and use drugs used for decades in the treatment of leprosy, a disease caused by Mycobacterium leprae, which is a bacteria closely related to Mycobacterium tuberculosis [4]. Minocycline, cotrimoxazole or sulfadiazine, and clofazimine are efficient in vitro and cured the treated patient. Finally, β-lactam antibiotics such as carbapenems or amoxicillin-clavulanate have been shown to be efficient in vitro and in a few cases [5]. I believe that you can teach an old dog new tricks [6], and that we have a heritage of antibiotics that we should not neglect in chasing after new compounds. The major problem currently is to determine who will pay to evaluate new therapeutic protocols if the pharmaceutical industry is not interested.