Totally Drug-Resistant TB Emerges In India

Some of it is. TB requires prolonged treatment. 3 months is regarded as the absolute minimum treatment duration. 6 months is suitable for most cases. 12-24 months is needed for severe cases, or for cases affecting certain organs (brain or spine). Anti-TB antibiotics also have severe side effects - liver damage, nerve damage, permanent eye damage, they severely disrupt the biochemistry of other drugs (potentially causing them to become ineffective, or overactive), etc.

In poorer countries, patients/doctors may not be able to afford a full course of drugs, and may therefore cut it short. Uneducated patients may also stop the treatment when they start to feel better, and not carry the course through to the end (and in poorer countries, there may not be a system for doctors/law enformcenet to trace them and bring them back for treatment).

Additionally, tests for TB have are very time-consuming and expensive. It can take 8 weeks to get a drug-sensitivity test, and that's if the test comes back positive anyway (one of the problems with TB, is that it is very good at hiding, and the bugs are very difficult to grow). Where funding is constrained, diagnosis is simply by looking for the bugs in a sputum specimen with a microscope - which tells you nothing about the sensitivities. There is a signficant cost of incubating the specimens on special growth media for 8 weeks, and a low success rate. Because of this, doctors in these countries may not be able to diagnose drug resistance, except when drugs fail to halt the disease after 6 months.

The avoidance of resistance in anti-biotic treatment is best achieved by mixing multiple drugs of different types. Conventionally TB is treated with a cocktail of 3 or 4 drugs. If, however, you use those 3 drugs, ih a population that is infected with a bug that is resistant to 2 of them, then resistance to the single functioning agent, can develop very rapidly.

Things are changing with advanced test kits and DNA amplification technology, which are able to detect the genes that confer resistance, and give a result, with high accuracy and high reliability within 24 hours. The problem is the significant cost of this testing technique.

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Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/d6FJsGCSdHA/totally-drug-resistant-tb-emerges-in-india

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