The incidence and prevalence of non-tuberculous mycobacterial (NTM) lung disease are increasing in the United States and many parts of the world. Among those >65 years old, the prevalence significantly increased from 20 cases per 105 in 1997 to 47 cases per 105 in 2007, a rate increase of 8.2% per year. The precise reason(s) for the rising number of patients with NTM lung disease remains largely unknown. It has been speculated that the surge in numbers may be the result of several factors, including greater awareness and improved diagnosis, increased environmental exposure, iatrogenesis from use of inhaled medications, and person-to-person spread. The purpose of this review is to discuss the various animal models that have been used to study the pathogenesis of NTM infection as well as screening candidate antimicrobials, which are essential endeavors if better control of NTM infection is to be achieved. We will neither discuss animal models for Mycobacterium leprae (nosologically not considered to be an NTM) nor Mycobacterium avium subspecies paratuberculosis (well known cause of disease in cattle but not man).
The most common NTM to cause lung disease belongs to the Mycobacterium avium complex (MAC) – historically comprised of M. avium and M. intracellulare – but with high-throughput gene sequencing, several more related species have been identified that are under the MAC umbrella, including M. chimaera.