Evidence for a previously unrecognized mycobacterial endosymbiont in Acanthamoeba castellanii strain Ma (ATCC ® 50370 ™).

We describe the isolation of a mycobacterium from Acanthamoeba castellanii strain Ma (ATCC(®) 50370(™)). The mycobacterium resides within vacuoles of A. castellanii, can be cultured by routine methodologies, and is a member of the Mycobacterium avium complex.