Sputum smear microscopy result: a predictor for drug-resistant tuberculosis?

Until countries establish capacity for continuous surveillance systems, representative surveys of tuberculosis (TB) patients continue to improve our understanding of the burden of drug-resistant TB and help ensure appropriate allocation of resources. Although the available data are limited, the current recommendation of restricting surveys to sputum smear-positive patients is justified, given the greatly simplified logistics and only limited evidence in specific settings of an association between drug resistance and sputum smear status. Nonetheless, the relationship between drug resistance and sputum smear microscopy results may vary according to the setting and population under study. With the increasing availability and use of molecular diagnostics and the drive for universal drug susceptibility testing under the World Health Organization's End TB Strategy, substantially more data on drug resistance in the whole TB patient population should become available in the near future.