Host determinants of infectiousness in smear-positive patients with pulmonary tuberculosis

Acuña-Villaorduña, Carlos, Ayakaka, Irene, Schmidt Castellani, Luiz Guilherme, Mumbowa, Francis, Rodrigues, Patrícia Patrícia Marques, Gaeddert, Mary, White, Laura Forsberg, Palaci, Moíses, Ellner, Jerrold J., R Dietze, Joloba, Moses Lutaakome, Fennelly, Kevin P., Edward C Jones-López

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Abstract

BACKGROUND: Epidemiologic data suggests that only a minority of tuberculosis (TB) patients are infectious. Cough aerosol sampling is a novel quantitative method to measure TB infectiousness. METHODS: We analyzed data from three studies conducted in Uganda and Brazil over a 13-year period. We included sputum acid fast bacilli (AFB) and culture positive pulmonary TB patients and used a cough aerosol sampling system (CASS) to measure the number of colony-forming units (CFU) of Mycobacterium tuberculosis in cough-generated aerosols as a measure for infectiousness. Aerosol data was categorized as: aerosol negative (CFU = 0) and aerosol positive (CFU > 0). Logistic regression models were built to identify factors associated with aerosol positivity. RESULTS: M. tuberculosis was isolated by culture from cough aerosols in 100/233 (43%) TB patients. In an unadjusted analysis, aerosol positivity was associated with fewer days of antituberculous therapy before CASS sampling (p = .0001), higher sputum AFB smear grade (p = .01), shorter days to positivity in liquid culture media (p = .02), and larger sputum volume (p = .03). In an adjusted analysis, only fewer days of TB treatment (OR 1.47 per 1 day of therapy, 95% CI 1.16-1.89; p = .001) was associated with aerosol positivity. CONCLUSION: Cough generated aerosols containing viable M. tuberculosis, the infectious moiety in TB, are detected in a minority of TB patients and rapidly become non-culturable after initiation of antituberculous treatment. Mechanistic studies are needed to further elucidate these findings.
Original languageEnglish
Article numberofz184
Pages (from-to)ofz184-ofz194
Number of pages9
JournalOpen Forum Infectious Diseases
VolumeVol. 6
Issue numbern.º 6
DOIs
Publication statusPublished - 3 Jun 2019

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Carlos, A-V., Irene, A., Luiz Guilherme, S. C., Francis, M., Patrícia Marques, R. P., Mary, G., ... Jones-López, E. C. (2019). Host determinants of infectiousness in smear-positive patients with pulmonary tuberculosis. Open Forum Infectious Diseases, Vol. 6(n.º 6), ofz184-ofz194. [ofz184]. https://doi.org/10.1093/ofid/ofz184