Mycobacterium fortuitum is one of the many species of nontuberculosis mycobacteria (NTM) that are commonly found in the environment. These are not involved in tuberculosis. This does not mean, however, that they will not cause an infection in the right circumstances.ackground [edit]. Mycobacterium fortuitum is a fast-growing species that can cause infections. The term fast growing is a reference to a growth rate of 3 or 4 days, when compared to other Mycobacteria that may take weeks to grow out on laboratory media.