Pyrazinamide Is Active against Mycobacterium tuberculosis Cultures at Neutral pH and Low Temperature.

For the past decades, an acidic pH has been used to render Mycobacterium tuberculosis susceptible to pyrazinamide for in vitro testing. Here, we show that at the standard breakpoint concentration and reduced culture temperatures, pyrazinamide (PZA) is active against tuberculosis (TB) at neutral pH. This finding should help unravel the mechanism of action of PZA and allow drug susceptibility testing (DST) methods to be optimized.