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Am J Respir Crit Care Med. 2012 Sep 1;186(5):450-7. doi: 10.1164/rccm.201203-0444OC. Epub 2012 Jul 12.

Variability of infectious aerosols produced during coughing by patients with pulmonary tuberculosis.

Author information

1
Southeastern National Tuberculosis Center, Emerging Pathogens Institute, Room 257, University of Florida, Gainesville, FL 32610, USA. kevin.fennelly@medicine.ufl.edu

Abstract

RATIONALE:

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 μm in size. Positive aerosol cultures were associated with higher Karnofsky performance scores (P = 0.016), higher sputum acid-fast bacilli smear microscopy grades (P = 0.007), lower days to positive in liquid culture (P = 0.004), stronger cough (P = 0.016), and fewer days on TB treatment (P = 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.

PMID:
22798319
PMCID:
PMC3443801
DOI:
10.1164/rccm.201203-0444OC
[Indexed for MEDLINE]
Free PMC Article
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