PURPOSE: The epidemiology of NTM is complicated by the difficulty in differentiating between colonization versus disease. Several studies have suggested an increase in the number of isolation and cases of NTM in both HIV positive and negative patients. The aim of the study was to assess the trend of NTM isolation in our institution.
METHODS: Retrospective review of medical records; number, source and year of NTM isolation and methods of culture.
RESULTS: From 1993 to 2005, there was a gradual decrease in number of specimens sent for Acid—Fast Bacilli (AFB) cultures from 6351 specimens in 1993 to 724 in 2005 (88.6% decline). Before 1994 Septic-Check AFB system was used, from 1994 BACTEM. Mycobacterium was isolated from 1327 patients; 708 (53%) had NTM and 618 (46.5%) M. tuberculosis (TB); in 1993, of all mycobacterium isolates, 27% were NTM compared to 86.4% in 2005; confirmed TB cases declined in this period by 86.5%. Of 708 patients with NTM: 562 (79.3%) had M. avium/Intracellulare complex (MAC), 38.3% with 2 or more positive specimens for MAC and 47/562 (8%) with both TB and MAC; M. gordonae (37 patients), M. Kansasii (33), M. Fortuitum (8), M. Hemophilus (3), M. Chelonae (6), M. szulgai (2), M. Malmonese (1), M. scrofulaceum (4), M. flavescense (2), M. simiae (1), M. xenopi (5), M. marinum (2), M. bovis (1). NTM was recovered from respiratory tract in 75.8% of the patients and from positive blood cultures in 12.8%; Overall, 35% of patients tested were HIV positive, 34% negative and 31% had unknown status.
CONCLUSION: The increase in proportion of NTM isolated from specimens submitted for mycobacterial cultures is likely due to decreasing number of cases of tuberculosis. The number of patients from whom NTM were isolated annually remained constant during this period, with MAC being the predominant species isolated.
CLINICAL IMPLICATIONS: Further investigation is needed to define the clinical significance of these isolates.
DISCLOSURE: Layola Lunghar, None.