Extensively Drug-resistant Tuberculosis: Epidemiology and Management Challenges

Widespread global use of rifampin for 2 decades preceded the emergence of clinically significant multidrug-resistant tuberculosis (MDR-TB) in the early 1990s. The prevalence of MDR-TB has gradually increased such that it accounts for approximately 5% of the global case burden of disease (approximately half a million cases in 2007). Eclipsing this worrying trend is the widespread emergence of extensively drug-resistant TB (XDR-TB). This article reviews the insights provided by clinical and molecular epidemiology regarding global trends and transmission dynamics of XDR-TB, and the challenges clinicians have to face in diagnosing and managing cases of XDR-TB. The ethical and management dilemmas posed by recurrent defaulters, XDR-TB treatment failures, and isolation of incurable patients are also discussed. Given the past global trends in MDR-TB, if aggressive preventive and management strategies are not implemented, XDR-TB has the potential to severely cripple global control efforts of TB.