Drug resistance in Mycobacterium tuberculosis

Abstract

Over 95% of tuberculosis (TB) cases and deaths among adults occur in developing countries. The emergence, management of cases, and spread of drug-resistant strains of Mycobacterium tuberculosis is one of the biggest challenges faced by national tuberculosis control programs. Multidrug-resistant TB (MDR-TB), defined as resistance to isoniazid and rifampicin, the two most potent anti-TB drugs, is increasing. MDR-TB is difficult and expensive to treat. Extensively drug-resistant TB (XDR-TB), defined as MDR-TB with additional resistance to a fluoroquinolone and one or more of the injectable anti-TB drugs, has been reported in many countries. Due to lack of diagnostic capacity, particularly in developing countries, the burden of MDR-TB and XDR-TB is not well known. Detection of drug-resistant TB is hindered by the difficulty and length of time required for its diagnosis while using conventional indirect drug susceptibility testing. Development and implementation of rapid methods for the diagnosis of drug-resistant TB are essential to long-term effective control of TB. Presented in this chapter are the terminology used in TB drug resistance, anti-TB drug groups, development and mechanism of drug resistance, and the conventional and new rapid susceptibility testing techniques. Finally, the treatment, control, and surveillancesurveillance for TB drug resistance are introduced.