Mentions: Formerly an unnamed Mycobacterium (Figure) sequevar within the M. avium–M. intracellulare–M. scrofulaceum group (MAIS), M. chimaera is an emerging opportunistic pathogen that can cause infections of heart valve prostheses, vascular grafts, and disseminated infections after open-heart surgery. Heater–cooler units used to regulate blood temperature during cardiopulmonary bypass have been implicated, although most isolates are respiratory. In 2004, Tortoli et al. proposed the name M. chimaera for strains that a reverse hybridization–based line probe assay suggested belonged to MAIS but were different from M. avium, M. intracellulare, or M. scrofulaceum. The new species name comes from the chimera, a mythological being made up of parts of 3 different animals.