Incidence of nontuberculous mycobacterial disease in New Zealand, 2004.

Aim: To record the incidence and clinical significance of nontuberculous mycobacteria (NTM) infection in New Zealand (NZ) in 2004.
Method: In 2004 each of NZ's mycobacterium reference laboratories collected data on NTM isolates. The clinical significance of isolates was decided by contacting the requesting clinician. American Thoracic Society criteria were used to assign clinical significance to respiratory isolates.
Results: 368 patients had NTM isolated from various sites. 21% (78/368) were clinically significant [15% (47/316) of respiratory isolates, 100% (17/17) lymph node and 89% (8/9) of soft tissue isolates]. Of the significant isolates, Mycobacterium avium intracellulare complex (MAIC) was the most common, accounting for 83%, 88%, and 44% of respiratory, lymph node, and soft tissue infections respectively. Rapidly growing mycobacteria (RGM) were the second most common cause of significant infection. Of 47 patients with significant respiratory isolates 79% were female and 83% had underlying lung disease. The incidence of disease caused by NTM in NZ in 2004 was 1.92/100,000 population. The specific incidence of pulmonary, lymph node and soft tissue infections was 1.17, 0.39, and 0.24 per 100,000 population respectively.
Conclusion: The incidence of NTM respiratory disease in NZ during 2004 is approximately twice that recorded for Australia in 2000 (0.56/100,000). MAIC is the most common pathogen, followed by RGM. Both organisms most commonly cause respiratory infections in elderly female patients with underlying lung disease.