Diagnosis and treatment of multidrug-resistant tuberculosis in developed and developing countries: Finally towards equality?

Abstract

Tuberculosis TB is considered a sobering example of inequity. It is a disease predominantly of the socially and economically disadvantaged. This neglect is evidenced by lack of political support, scarce financial resources for TB programs, and little or no leadership.

The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is threatening global TB control and it represents a major challenge for clinical care and operational management. Worldwide, 3.7% of new cases and 20% of previously treated cases are estimated to have MDR-TB. Unfortunately, since only a quarter of patients with MDR-TB are treated according to established standards and the proportion of treatment success does not exceed 50%, extensively drugresistant tuberculosis (XDR-TB) has already been reported in 84 countries and totally drug resistant cases have been recently described.

In most low- and middle-income countries drug sensitivity testing is not performed for new cases or for most patients requiring retreatment. Therefore, patients with underlying drug resistance will receive retreatment with first line drugs and can be predicted to have higher rates of failure and relapse.

The development of genotypic methods has generated a genuine revolution in the diagnosis of DR-TB. The polymerase chain reaction allows for the specific identification of M. tuberculosis and the detection of drug resistance in a matter of hours instead of weeks. Unfortunately these techniques are expensive and not available in most high burden countries.

Despite the enormous number of cases of TB worldwide, the therapeutic arsenal to treat this disease continues to be very limited, especially for cases with extensive drug resistance. However, for the first time in decades, the pipeline of new anti-TB agents is now growing again inasmuch as new drugs and combination of drugs with interesting potential efficacy to treat TB, MDR-TB and XDR-TB have appeared during the last few years.