Epidemiology and treatment of multidrug resistant tuberculosis

Abstract

Multidrug resistant tuberculosis is now thought to afflict between 1 and 2 million patients annually. Although significant regional variability in the distribution of disease has been recorded, surveillance data are limited by several factors. The true burden of disease is likely underestimated. Nevertheless, the estimated burden is substantial enough to warrant concerted action. A range of approaches is possible, but all appropriate interventions require scale-up of laboratories and early treatment with regimens containing a sufficient number of second-line drugs. Ambulatory treatment for most patients, and improved infection control, can facilitate scale-up with decreased risk of nosocomial transmission. Several obstacles have been considered to preclude worldwide scale-up of treatment, mostly attributable to inadequate human, drug, and financial resources. Further delays in scale-up, however, risk continued generation and transmission of resistant tuberculosis, as well as associated morbidity and mortality.

Figure 1

Amplifier effect of repeated, standardized regimens. Example of how selective pressure of repeated standardized regimens (represented by white letters on dark background over arrow) can result in serial acquisition of resistance (represented by dark letters on light background under arrow), ultimately XDR-TB.

Figure 2

Global distribution of XDRTB, reported through February 2008. Adapted from reference .

Figure 3

Possible strategies for screening and referral to treatment for DR-TB.