Mycobacteriocidal action of exogenous nitric oxide

We tested the hypothesis that exposure of extracellular Mycobacterium tuber culosis to low concentrations (<100 ppm) of nitric oxide (NO) for short per iods (24 h or less) will result in microbial killing. We observed that NO h ad both dose- and time-dependent cidal effects that were very significant b y two-way analysis of variance (F ratios of 13.4 [P < 0.001] and 98.1 [P < 0.0001], respectively). Conceivably, extracellular bacilli in patients with pulmonary tuberculosis might be vulnerable to exogenous NO.