Nontuberculous mycobacterial disease in northern Australia: A case series and review of the literature

We performed a retrospective/prospective review of all cases of disease due to nontuberculous mycobacteria (NTM) reported in the Northern Territory, A ustralia, during the period 1989-1997. Fifty-eight cases were reported, wit h an average yearly incidence of 3.9 cases per 100,000 persons. The number increased significantly for the second half of the study period (39 vs. 19 cases; P<.02). The yearly incidence of pulmonary Mycobacterium avium/Mycoba cterium intracellulare complex (MAC) disease not associated with human immu nodeficiency virus (HIV) infection was 2.1 cases per 100,000 population. MA C was the most common isolate (78%) and pulmonary disease the most frequent clinical presentation (62%). Disease due to NTM or MAC was not found more commonly in rural areas. Significant risks for non-HIV-associated pulmonary MAC disease included male sex (odds ratio [OR], 2.1; 95% confidence interv al [CI], 1.0-4.5) and age >50 years (OR, 26.5; 95% CI, 10.9-67.3), but abor iginal people appeared underrepresented (OR, 0.77; 95% CI, 0.30-1.87). Myco bacterium tuberculosis was almost 5 times more likely than NTM to be the ca use of non-HIV-associated mycobacterial pulmonary disease (153 vs. 32 cases ; OR, 4.79; 95% CI, 3.22-7.14). Mycobacterial lymphadenitis in aboriginal c hildren was more likely to be tuberculous than nontuberculous (OR, 6.5; 95% CI, 1.4-41.7), but not in nonaboriginal children (OR, 1.0)With treatment, 66% ir of the cases of non-HIV-associated pulmonary MAC disease had favorab le outcomes, and 7% of patients had progressive fatal disease. Outcomes of therapy for lymphadenitis and skin/soft-tissue disease were excellent, but those of HIV-associated disseminated MAC disease were poor.