In addition to TB, atypical mycobacteria are also frequently reported as causative pathogens in IRIS. Early observations involving atypical presentations of Mycobacterium avium-intracellulare (MAC) were first noted with zidovudine therapy [55] . Reports of atypical presentations of both Mycobacterium tuberculosis (MTB) and MAC increased in frequency with the introduction of protease inhibitors and ART. In larger cohorts, MAC remains the most frequently reported atypical mycobacterium [4, 5, 24] . Other atypical mycobacteria rarely associated with IRIS are referenced in Table 1 .