(A) Killing of BCG by D155931 was time dependent and synergistic with nitrite. BCG was treated at pH 5.5 (which prevents its replication) with 10 μM D155931 (squares) or DMSO (circles) without (black symbols) or with (white symbols) 0.5 mM nitrite for 4 days. Nitrite alone at this concentration caused no killing.
(B) Killing of BCG by D155931 was concentration-dependent. BCG was treated with D155931 at pH 5.5 without (black symbols) or with 0.5 mM nitrite (white symbols) for 4 days. Dashed line denotes inoculum.
(C) D155931 only killed nonreplicating Mtb synergistically with nitrite. Mtb H37Rv was treated for 4 days with D155931 at pH 5.5 (which does not prevent its replication) without (black symbols) or with 0.5 mM nitrite (white symbols). Dashed line denotes inoculum. Results are means ± SD of triplicates in single experiments, each of which was repeated at least two times.