Tuberculosis: an experience from Mycobacterium smears and culture analysis.

Objective: Simple tests like direct smear of the acid fast bacilli (AFB) and Mycobacterium culture could assist the diagnosis of tuberculosis. This study is aimed at reviewing the outcome of smears, culture results and contamination rate among specimens requested for AFB smear and Mycobacterium culture. Methods: Retrospective laboratory data analysis requesting for Mycobacterium culture from January 2005 till December 2006 was done in a tertiary teaching hospital of Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Results: Four hundred and sixty seven (36.6%) isolates grew from 1 277 specimens. Of these isolates, 314 (67.2%) grew Mycobacterium tuberculosis, 23 (4.9%) grew Mycobacterium other than tuberculosis and 38 (8.1%) grew contaminants. Among the M. tuberculosis cultures, 165 (52.5%) had growth of more than 100 confluent colonies, whereas 39 cultures (12.4%) had growth of less than 19 colonies. Direct smear for AFB among smear positive cases showed presence of more than 50 bacilli/line in 231 (49.5%) cases and smear negative cases accounted for 63 (13.5%). Among smear positive cases, 291 (94.5%) cultures grew Mycobacterium species and another 17 (5.5%) cultures grew contaminants. In smear negative cases, 32 (62.7%) cultures grew Mycobacterium species and 19 (37.3%) cultures grew contaminants. Conclusion: The results from data analysis of the Mycobacterium cultures should be critically utilized in order to review the laboratory performance and to improve its services in the future. Some of the data is also useful to the administrators of the hospital in terms of estimating the risk of occupational hazard faced by the health care workers.