Context

In 2009, there were more than 9 million new cases of tuberculosis, but only 63% were diagnosed. The situation for multidrug-resistant tuberculosis (MDR-TB) was even more dismal, with less than 12% of the estimated 250 000 cases diagnosed.1 The most important cause for the diagnostic gap was the absence of a rapid and sensitive test. Smear microscopy, the most widespread first-line diagnostic, is cheap and simple but has poor sensitivity and cannot detect resistance. Culture is highly sensitive and can identify drug resistance, but it requires a sophisticated laboratory infrastructure and is slow. Following a large evaluation study,2 the WHO recommended Xpert MTB/RIF (Xpert), a highly automated real-time PCR assay, as the initial diagnostic test for people suspected …