Duration of pulmonary tuberculosis infectiousness under adequate therapy, as assessed using induced sputum samples

Yousang Ko, Jeong Hwan Shin, Hyun Kyung Lee, Young Seok Lee, Suh Young Lee, So Young Park, Eun Kyung Mo, Changhwan Kim, Yong Bum Park

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5 Scopus citations


Background: A sputum culture is the most reliable indicator of the infectiousness of pulmonary tuberculosis (PTB); however, a spontaneous sputum specimen may not be suitable. The aim of this study was to evaluate the infectious period in patients with non-drug-resistant (DR) PTB receiving adequate standard chemotherapy, using induced sputum (IS) specimens. Methods: We evaluated the duration of infectiousness of PTB using a retrospective cohort design. Results: Among the 35 patients with PTB, 22 were smear-positive. The rates of IS culture positivity from baseline to the sixth week of anti-tuberculosis medication in the smear-positive PTB group were 100%, 100%, 91%, 73%, 36%, and 18%, respectively. For smear-positive PTB cases, the median time of conversion to culture negativity was 35.0 days (range, 28.0-42.0 days). In the smear-negative PTB group (n=13), the weekly rates of positive IS culture were 100%, 77%, 39%, 8%, 0%, and 0%, respectively, and the median time to conversion to culture-negative was 21.0 days (range, 17.5-28.0 days). Conclusion: The infectiousness of PTB, under adequate therapy, may persist longer than previously reported, even in patients with non-DR PTB.

Original languageEnglish
Pages (from-to)27-34
Number of pages8
JournalTuberculosis and Respiratory Diseases
Issue number1
StatePublished - Jan 2017

Bibliographical note

Publisher Copyright:
Copyright © 2017 The Korean Academy of Tuberculosis and Respiratory Diseases. All rights reserved.


  • Induced sputum
  • Infectious disease incubation period
  • Mycobacterium tuberculosis
  • Pulmonary
  • Tuberculosis


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