In contrast to M. abscessus, M. fortuitum demonstrates broader in vitro susceptibility to both oral and intravenous antimicrobial drugs, including the newer macrolides, the fluoroquinolones, doxycycline, minocycline, the sulfonamides, and two intravenous drugs, imipenem and cefoxitin.Although most isolates of M. fortuitum are susceptible in vitro to the macrolides, these drugs should be used with caution because of the presence of an inducible erm gene.
Mycobacterium fortuitum lung disease should be treated with at least two drugs to which in vitro susceptibility has been demonstrated.As with other NTM lung infections, treatment should be continued for at least 12 months of negative sputum cultures. Skin, soft tissue, and bone infections should be treated similarly to M. abscessus infections, although oral agents are more often effective.