ycobacterium fortuitum and Mycobacterium peregrinum are nontuberculous mycobacteria (NTM). They belong to a subset of NTM known as rapid-growing mycobacteria (RGM), previously designated as Runyon class IV. Rapid-growing mycobacteria are saprophytic, ubiquitous in nature, and generally considered non-pathogenic. Several species of RGM, including M fortuitum and M peregrinum, are potentially pathogenic in humans. Mycobacterium fortuitum infections are typically cutaneous, occurring when the skin barrier has been breached. No pattern of infection by M peregrinum has been established. Herein, we discuss a pediatric case of otomastoiditis that progressed to petrous apicitis, intracranial empyema, and meningitis despite appropriate medical and surgical therapy. Initial laboratory identification in this case listed M fortuitum with a follow-up laboratory identification by the Centers for Disease Control and Prevention (CDC) listing the M fortuitum/M peregrinum group. Because the CDC did not classify to the species level we cannot be certain that this case was not caused by M peregrinum, which phylogenetically is very closely related to M fortuitum. It is a member of the M fortuitum group and was considered a biovariant of M fortuitum until 1992. There are no previous reports of M peregrinum causing an otologic infection in the literature. To our knowledge, only 2 cases of mastoiditis and 1 case of a subdural empyema in the pediatric population caused by M fortuitum are documented in the literature. Considering the aggressive nature and serious otologic and intracranial consequences of these rapid growing mycobacteria, it is important to document this in the literature.