mycobacterium houstonense mycobacterium houstonense mycobacterium houstonense is a member of the mycobacterium fortuitum third biovariant complex. the specific epithet houstonense refers to houston, texas, where the first isolate of the m. fortuitum third biovariant (sorbitol-positive) was identified. mycobacterium houstonense scientific classification domain: bacteria phylum: actinomycetota class: actinomycetia order: mycobacteriales family: mycobacteriaceae genus: mycobacterium species: m. houstonense binomial name mycobacterium houstonenseschinsky et al., 2004 type strain atcc 49403