Tuberc Respir Dis.  2001 Oct;51(4):325-333. 10.4046/trd.2001.51.4.325.

Clinical Outcome after Treatment with the First-line Drugs in Patients with Persistent Positive Sputum Smear and Negative Sputum Culture Results


This study aimed to estimate the clinical outcome and identify the characteristics of a group of patients with pulmonary tuberculosis who completed anti-tuberculosis therapy with the First-line drugs in spite of having positive smear results with negative sputum culture results over the previous six months. METHOD: A retrospective chart review of 21 patients who fulfilled the above criteria between 1995 and 1999 was performed. The laboratory data as well as the clinical data of the patient with positive smear results and negative culture results over a six months period were reviewed.
The negative conversion of sputum culture results was achieved within 1.3±1.2 months and the negative conversion of the sputum smear results was accomplished during 9.5±3.3 months. Chest X-rays at 5 months following the institution of anti-tuberculosis therapy from all patients revealed improvements. Four out of 21 patients(19%) relapsed during the follow up, 15.2±13.4 months after administering anti-tuberculosis therapy for 13.3±3.1 months. Relapses were confirmed from between 3 months and 4 months after the treatment completion. Only one of the four relapses had no past history of anti-tuberculosis therapy and the others had prior treatment twice (p<0.01). The period of anti-tuberculosis treatment was extended to a mean of 4.6±2.6 months in 12 patients. However, prolongation of anti-tuberculosis therapy had no affect on the relapse rate (odds ratio, 95% CI 0.18, 2.15).
Prolongation of therapy with the First-line drugs is not necessary for patients with persistently positive smear results over 6 months and negative culture results. A patient who has had prior anti-tuberculosis therapy more than twice should be paid the closest attention.


Pulmonary tuberculosis; Smear-positive; Culture-negative
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