Role of mycobacterium culture in the diagnosis of smear negative pulmonary tuberculosis suspects attending tertiary care setting

ABSTRACT

Sputum smear testing for acid fast bacilli is the gold standard for the diagnosis of tuberculosis. The role of culture in cases that are negative on sputum smear testing is being emphasized for early diagnosis of disease and prompt initiation of treatment. To correlate the role of culture in diagnosing smear-negative pulmonary tuberculosis suspects. Descriptive study carried out in chest clinic of Sir Ganga Ram Hospital, Lahore in collaboration with Institute of Public Health Lahore from January 2012 to June 2012. Materials and Adults over 15 year of either gender having symptoms and X-ray findings consistent with pulmonary tuberculosis were selected. The sputa of sputum smear negative cases were inoculated on Lowenstein-Jensen medium culture medium to isolate the organism and correlate the culture positivity and negativity in smear negative cases. A total of 88 sputa were negative for acid fast bacilli on smear which were subjected to culture on Lowenstein-Jensen medium. Of these 31[35%] grew acid fast bacilli and were thus confirmed positive by culture while rest 57 remained negative on culture. There was no significant difference in the symptoms and extent of lesions on X-ray between those who were culture positive or negative. Sputum culture should be done for the diagnosis or exclusion of smear negative clinically suspected and X-ray positive cases of pulmonary tuberculosis. Policy message All clinically suspected and X-ray positive but sputum smear negative cases should undergo sputum culture for Mycobacterium tuberculosis on Lowenstein-Jensen medium. The facilities to culture the micro organism should be made available at district level by the tuberculosis control program