G. Comina's research stay at Linkoping University has been financed by the Peruvian National Council for Science and Technology (CONCYTEC). This research has been supported by grants from Linkoping Centre for Life Science Technologies (LIST), Sweden, and from the Swedish Research Council (VR).

This work was funded in part by National Institutes of Health through awards 5D43TW006581 "Infectious Diseases Training Program in Peru'' and R21 AI094143 "Cough-A Rapid Indication of Response to Therapy in Pulmonary Tuberculosis''. JL and MB were supported by NIH Fogarty Foundation fellowships. G. Comina wants to thank the Consejo Nacional de Ciencia, Tecnologia e Innovacion Tecnologica of Peru (CONCYTEC) for their support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Tuberculosis (TB) is a significant cause of morbidity and mortality worldwide. The patient compliance with the long treatment regimens is essential for successful eradication. Pyrazinamide (PZA) shortens these regimens from 9 to 6 months, and therefore, improves treatment completion rates. Although PZA is a first-line medication for the treatment of TB, no simple or reliable assay to determine PZA resistance is yet available. In the presence of PZA, only susceptible Mycobacterium tuberculosis strains release pyrazinoic acid (POA). Therefore, the measurement and quantification of released POA is an indicator of PZA resistance.