High yield of culture-based diagnosis in a TB-endemic setting
Date
2012-09
Authors
Demers, Anne-Marie
Verver, Suzanne
Boulle, Andrew
Warren, Robin
Van Helden, Paul
Behr, Marcel A.
Coetzee, David
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Abstract
Background
In most of the world, microbiologic diagnosis of tuberculosis (TB) is limited to microscopy. Recent guidelines recommend culture-based diagnosis where feasible.
Methods
In order to evaluate the relative and absolute incremental diagnostic yield of culture-based diagnosis in a high-incidence community in Cape Town, South Africa, subjects evaluated for suspected TB had their samples processed for microscopy and culture over a 21 month period.
Results
For 2537 suspect episodes with 2 smears and 2 cultures done, 20.0% (508) had at least one positive smear and 29.9% (760) had at least one positive culture. One culture yielded 1.8 times more cases as 1 smear (relative yield), or an increase of 12.0% (absolute yield). Based on the latter value, the number of cultures needed to diagnose (NND) one extra case of TB was 8, compared to 19 if second specimens were submitted for microscopy.
Conclusion
In a high-burden setting, the introduction of culture can markedly increase TB diagnosis over microscopy. The concept of number needed to diagnose can help in comparing incremental yield of diagnosis methods. Although new promising diagnostic molecular methods are being implemented, TB culture is still the gold standard.
Description
The original publication is available at http://www.biomedcentral.com/1471-2334/12/218
Keywords
Tuberculosis -- Diagnosis, Tuberculosis -- Microbiology
Citation
Demers, A-M. et al. 2012. High yield of culture-based diagnosis in a TB-endemic setting. BMC Infectious Diseases, 12(1):218, doi:10.1186/1471-2334-12-218.