16.3  Drug-resistant TB and multi-drug resistant TB

The emergence of resistance to anti-tuberculosis drugs, and particularly of multidrug resistant-TB (MDR-TB) arises when TB bacteria develop resistance to rifampicin and isoniazid. MDR-TB has become a major public health problem in a number of countries and an obstacle to effective global TB control. When a patient has TB with bacteria that are no longer sensitive to one or more anti-TB drugs, for instance isoniazid, using this antibiotic will not be helpful. Other drugs (known as second-line drugs) have to be used instead of the first-line drug regimens.

A good TB control programme — especially with regard to patient follow-up and adherence, will not generate much drug resistance. Resistance to TB drugs usually occurs as a consequence of inadequate treatment, be it irregular, too short or too weak. Resistant TB bacteria can be transmitted to other people like any other form of TB.