Chemoprophylactic Antimicrobial Activity of Gallium Maltolate against Intracellular Rhodococcus equi

The objective of this study was to assess the ability of prophylactically administered gallium maltolate (GaM) to inhibit growth or kill Rhodococcus equi within murine macrophage-like (J774A.1) cells. Cells were treated with three different doses of GaM or a single dose of maltol (equivalent to the concentration present in the highest dose of GaM studied); they were then infected with virulent R. equi and incubated. Quantitative cultures of R. equi from lysed macrophages were obtained at 0, 24, 48, and 72 hours. All GaM dosages resulted in significant reductions of intracellular R. equi compared with untreated control cells, and a dose–response effect was evident. Maltol treatment alone had no significant effect on intracellular R. equi concentrations compared with untreated control cells. Results suggest the potential usefulness of gallium maltolate for the prevention or control of R. equi infections.