Number of sputum specimens during treatment follow-up of tuberculosis patients: two or one?

Kumar, R.S.; Kumar, A.M.V; Claassens, M.; Banurekha, V.V.; Gomathi, N.S.; Venkatesan, P.; Swaminathan, S.

Public Health Action; 2013; 3; 304–307.

Setting: National Institute for Research in Tuberculosis clinics in Chennai and Madurai , India .

Objective: To examine the pattern of serial smears (negative-negative [NN], negative-positive [NP], positive negative [PN], positive-positive [PP]) during treatment follow-up of culture-confirmed new smear-positive tuberculosis (TB) patients, and the proportion of culture negatives in each category.

Design: We reviewed the records and extracted follow-up smear (fluorescent microscopy) and culture (Löwenstein-Jensen) results of patients enrolled in clinical trials from January 2000 to August 2012 and treated with the Category I regimen (2EHRZ 3 /4HR 3 ). Data entry and analysis were performed using EpiData.

Results: Among 520 patients (176 infected with the human immunodeficiency virus), the proportions of culture negative patients with NN, discordant (PN or NP) and PP patterns were approximately 98%, 80% and 40%, respectively. The smear-positive culture-negative phenomenon was more frequent in follow-up smear results graded 1+, followed by 2+ and 3+.

Conclusion: There is justification for discontinuing the examination of second specimens during treatment follow-up among TB patients. However, a positive result on the first smear needs to be confirmed by a second positive result before making clinical management decisions. The World Health Organization may need to reconsider its recommendation on this issue.

Keywords: smear-positive, culture negative; sputum smear; sputum culture; pulmonary TB

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