Use of simulated sputum specimens to estimate the specificity of laboratory-diagnosed tuberculosis

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dc.contributor.authorDemers A.-M.
dc.contributor.authorBoulle A.
dc.contributor.authorWarren R.
dc.contributor.authorVerver S.
dc.contributor.authorVan Helden P.
dc.contributor.authorBehr M.A.
dc.contributor.authorCoetzee D.
dc.date.accessioned2011-05-15T15:53:45Z
dc.date.available2011-05-15T15:53:45Z
dc.date.issued2010
dc.description.abstractSETTING: Cross-contamination is not uncommon in mycobacteriology laboratories of high-income countries, as documented by bacterial genotyping. The extent of this problem in low-income countries is largely unknown, where this method is impractical. OBJECTIVE: To estimate the rate of cross-contamination in a high-volume tuberculosis (TB) laboratory in South Africa. DESIGN: Simulated sputum specimens labelled with false names were sent from a TB clinic, interspersed with patient samples, and processed for culture and microscopy. Results were interpreted in the context of the observed proportion of samples with positive microscopy and culture results. RESULTS: With microscopy, 6/190 (3.2%) simulated specimens were positive (estimated specificity = 96.8%). Considering the 881 positive microscopy results in 6093 clinical samples, we extrapolate that 19.3% (95%CI 7.0-42.8) of positive smears were false-positives. On culture, 2/190 (1.1%) of the simulated specimens were positive for Mycobacterium tuberculosis (estimated specificity = 98.9%). Considering the 1862 positive cultures from 6093 clinical samples, we estimate that 2.4% (95%CI 0.3-8.8) of positive cultures were false-positives. CONCLUSION: Simulated specimens offer a simple means of estimating the proportion of false-positive results, providing information on all sources of potential error from the clinic, through the laboratory and to reporting of results. © 2010 The Union.
dc.description.versionArticle
dc.identifier.citationInternational Journal of Tuberculosis and Lung Disease
dc.identifier.citation14
dc.identifier.citation8
dc.identifier.issn10273719
dc.identifier.urihttp://hdl.handle.net/10019.1/8792
dc.titleUse of simulated sputum specimens to estimate the specificity of laboratory-diagnosed tuberculosis
dc.typeArticle
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