Variability of Infectious Aerosols Produced during Coughing by Patients with Pulmonary Tuberculosis
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
American journal of respiratory and critical care medicine
Abstract
Mycobacterium tuberculosis is transmitted by infectious
aerosols, but assessing infectiousness currently relies on sputum
microscopy that does not accurately predict the variability
in transmission.
Objectives: To evaluate the feasibility of collecting cough aerosols
and the risk factors for infectious aerosol production from patients
with pulmonary tuberculosis (TB) in a resource-limited setting.
Methods: We enrolled subjects with suspected TB in Kampala,
Uganda and collected clinical, radiographic, and microbiological
data in addition to cough aerosol cultures. A subset of 38 subjects
was studied on 2 or 3 consecutive days to assess reproducibility.
Measurements and Main Results: M. tuberculosis was cultured from
cough aerosols of 28 of 101 (27.7%; 95% confidence interval [CI],
19.9–37.1%) subjects with culture-confirmed TB, with a median 16
aerosol cfu (range, 1–701) in 10 minutes of coughing. Nearly all
(96.4%) cultivable particles were 0.65 to 4.7 mm in size. Positive
aerosol cultures were associated with higher Karnofsky performance
scores (P ¼ 0.016), higher sputum acid-fast bacilli smear microscopy
grades (P ¼ 0.007), lower days to positive in liquid culture (P ¼
0.004), stronger cough (P ¼ 0.016), and fewer days on TB treatment
(P ¼ 0.047). In multivariable analyses, cough aerosol cultures were
associated with a salivary/mucosalivary (compared with purulent/
mucopurulent) appearance of sputum (odds ratio, 4.42; 95% CI,
1.23–21.43) and low days to positive (per 1-d decrease; odds ratio,
1.17;95%CI, 1.07–1.33). The within-test (kappa, 0.81; 95%CI, 0.68–
0.94) and interday test (kappa, 0.62; 95% CI, 0.43–0.82) reproducibility
were high.
Conclusions: A minority of patients with TB (28%) produced culturable
cough aerosols. Collection of cough aerosol cultures is feasible
and reproducible in a resource-limited setting.
Description
Keywords
Tuberculosis, Cough, Air microbiology, Infectious disease transmission, Infection control
Citation
Fennelly, K. P., Jones-López, E. C., Ayakaka, I., Kim, S., Menyha, H., Kirenga, B., ... & Ellner, J. J. (2012). Variability of infectious aerosols produced during coughing by patients with pulmonary tuberculosis. American journal of respiratory and critical care medicine, 186(5), 450-457. DOI: 10.1164/rccm.201203-0444OC