Drug-resistant tuberculosis: entering the mainstream
What is drug resistance and how does it develop? In the case of TB, resistance to drugs – when the effectiveness of a drug against a pathogen is reduced – develops through a mutation of genes in the bacteria. Although this is a natural phenomenon resistant bacteria will only multiply in the presence of the drug in question. Resistance can also develop if the bacteria are underexposed to drugs, because of under-dosing or if the treatment is interrupted or not continued for long enough. In all of these cases, treatment is likely to fail and the disease will re-emerge in a more resistant form, meaning that fewer drugs will be effective against the bacteria.
© Alessandra Vilas Boas
But direct infection with resistant strains is also possible. Because TB is an airborne disease, a patient can contract drug-resistant TB directly through contact with another person already ill with the drug-resistant strain. There are concerns that the number of those directly infected this way is rapidly increasing.
MDR-TB patient, Lesotho
For instance in Tashkent in Uzbekistan, 15 percent of TB cases who have never been previously treated for TB have MDR-TB, that is to say the resistant strain was caught directly from another person with MDR-TB.15
Diagnosis: establishing which drugs work, and which don’t
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Basically with drug-resistant TB, whenever you look for it, you find it. And when you try to deal with it, you inevitably run up against the shortcomings of the available diagnostic tools and treatment. What we are also finding is that more and more patients we see have drug-resistant TB and they come to us with ever more resistant forms of the disease. Dr. Juliet Melzer, MSF, Uzbekistan
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