Comparison of the antimicrobial activities of gallium nitrate and gallium maltolate against Mycobacterium avium subsp. paratuberculosis in vitro.

Johne's disease (JD) is an enteric infection of cattle and other ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This study compared the antimicrobial activities of gallium nitrate (GaN) and gallium maltolate (GaM) against two field MAP isolates by use of broth culture. The concentrations that resulted in 99% growth inhibition of isolates 1 and 2 were, respectively, 636 µM and 183 µM for GaN, and 251 µM and 142 µM for GaM. For both isolates, time to detection was significantly higher for GaM than GaN. These results suggest that GaM is more efficient than GaN in inhibiting MAP growth in vitro.