Mycobacterium avium complex and Mycobacterium abscessus complex (MAC and MABC)

Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MABC) are groups of non-tuberculous mycobacteria (NTM) that serve as significant opportunistic pathogens in humans, particularly in those with underlying structural lung diseases like bronchiectasis or cystic fibrosis (Daley CL, et al., 2020, Eur Respir J). MAC is the most common cause of NTM-associated pulmonary disease worldwide, while MABC is recognized as one of the most antibiotic-resistant mycobacteria, often requiring aggressive and prolonged therapeutic interventions (Nessar R, et al., 2012, J Antimicrob Chemother). These organisms are not single molecular targets but are complex biological entities containing multiple essential drug targets, such as the ribosome, RNA polymerase, and ATP synthase (Griffith DE, et al., 2007, Am J Respir Crit Care Med). Their thick, lipid-rich cell wall acts as a formidable barrier to many antibiotics, contributing to their environmental resilience and clinical persistence. Treatment typically involves multi-drug regimens including macrolides and aminoglycosides, but success is frequently hindered by the presence of inducible resistance genes like erm(41) in MABC (Philley JV & Griffith DE, 2013, Seminars in Respiratory and Critical Care Medicine). Consequently, these complexes represent a major therapeutic challenge due to the limited efficacy and high toxicity associated with long-term antibiotic therapy.

Other names

Non-tuberculous mycobacteriaNTMMycobacterium avium-intracellulare complexMACMABCOpportunistic mycobacteria

Drugs targeting these complexes act through various mechanisms: macrolides inhibit the 50S ribosomal subunit; aminoglycosides and tetracyclines inhibit the 30S ribosomal subunit; rifamycins inhibit DNA-dependent RNA polymerase; ethambutol inhibits arabinosyltransferase in cell wall synthesis; and bedaquiline inhibits mycobacterial ATP synthase.