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.

Details

Title
Host Determinants of Infectiousness in Smear-Positive Patients With Pulmonary Tuberculosis
Author
Acuña-Villaorduña, Carlos 1 ; Ayakaka, Irene 2 ; Luiz Guilherme Schmidt-Castellani 3 ; Mumbowa, Francis 4 ; Marques-Rodrigues, Patricia 3 ; Gaeddert, Mary 5 ; White, Laura F 6 ; Palaci, Moises 3 ; Ellner, Jerrold J 5 ; Dietze, Reynaldo 7 ; Moses Joloba 4 ; Fennelly, Kevin P 8 ; Jones-López, Edward C 5 

 Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Massachusetts; Lemuel Shattuck Hospital, Boston University School of Public Health, Massachusetts 
 Mulago Hospital Tuberculosis Clinic, Mulago Hospital, Kampala, Uganda 
 Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo, Vitória, Brazil 
 Department of Microbiology, Makerere University College of Medicine, Kampala, Uganda 
 Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Massachusetts 
 Department of Biostatistics, Boston University School of Public Health, Massachusetts 
 Núcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo, Vitória, Brazil; Global Health & Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisbon, Portugal 
 Pulmonary Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 
Publication year
2019
Publication date
Jun 2019
Publisher
Oxford University Press
e-ISSN
23288957
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3170973414
Copyright
© The Author(s) 2019. Published by Oxford University Press on behalf of Infectious Diseases Society of America. This work is published under http://creativecommons.org/licenses/by-nc-nd/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.