Dual <i>M. kansasii</i> infection in one household: a reconsideration of our understanding of transmission routes

Mycobacterium kansasii is one of the the most common non-tuberculous mycobacteria responsible for opportunistic human infection. Unlike M. tuberculosis , transmission remains poorly understood; spread is assumed to be from a shared geographical source, such as domestic plumbing, and human-to-human transmission is generally not considered by clinicians when evaluating patients and their environments. We describe M. kansasii infection in a husband and wife in the same household and in the same period, suggesting, in these cases, that transmission occurred directly from one patient to the other. This possibility of human-to-human transmission may inform a clinician’s scrutiny of risks to household contacts in cases of M. kansasii infection.