Re: "Turning back the tuberculosis tide."[1] My group has published a number of studies and reviews that provide evidence that phenothiazines have activity against all strains of Mycobacterium tuberculosis regardless of their antibiotic susceptibitility status.[2,3] We have shown over the past 15 years that although phenothiazines have in vitro activity against tuberculosis (TB), the concentrations needed are in the order of 20 ug/ml and the maximum concentration that can be achieved in a human is less than 0.5 ug/ml. Because TB is an intracellular infection, any drug must work against intracellular TB, and, more importantly, intra-cellular multidrug-resistant tuberculosis. We have demonstrated that this is the case at phenoziathine concentrations as low as 0.1 ug/ml.[4] We are therefore heartened that the TB Alliance is interested in the potential use of phenothiazines for TB.