Setting: A teaching hospital in the Republic of Korea, 2003-2009.
Objective: To evaluate the effect of previous tuberculosis (TB) treatment history on sputum smear and culture conversion.
Design: Data, including sputum acid-fast bacilli (AFB) results at baseline and at weeks 2, 4, 8, 12, 16, 20 and 24, were collected from patients with AFB sputum smear-positive and culture-confirmed pulmonary TB. Patients with multidrug-resistant TB or those with poor adherence were excluded. AFB conversion was compared between patients with a previous history of anti-tuberculosis treatment and those without.
Results: The median age of the 208 patients was 49.0 years; 58.3% were male, while 43 (20.7%) had a history of previous anti-tuberculosis treatment. Patients with a history of previous treatment had significantly lower sputum smear-negative conversion at 2 weeks of treatment compared with patients without (70.0% vs. 44.8%, P = 0.005). However, the two groups did not differ in culture conversion and in smear conversion at 4, 8, 12, 16, 20 and 24 weeks of anti-tuberculosis treatment.
Conclusion: Patients with a history of previous anti-tuberculosis treatment are more likely to have positive sputum AFB smear at 2 weeks of treatment. However, sputum culture conversion is not affected by previous treatment history.