Empiric treatment of pulmonary TB in the Xpert era: Correspondence of sputum culture, Xpert MTB/RIF, and clinical diagnoses
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Date
2019
Journal Title
Journal ISSN
Volume Title
Publisher
PLoS ONE
Abstract
Clinical tuberculosis diagnosis and empiric treatment have traditionally been common
among patients with negative bacteriologic test results. Increasing availability of rapid
molecular diagnostic tests, including Xpert MTB/RIF and the new Xpert Ultra cartridge, may
alter the role of empiric treatment.
Methods
We prospectively enrolled outpatients age > = 15 who were evaluated for pulmonary tuberculosis
at three health facilities in Kampala, Uganda. Using sputum mycobacterial culture,
interviews, and clinical record abstraction, we estimated the accuracy of clinical diagnosis
relative to Xpert and sputum culture and assessed the contribution of clinical diagnosis to
case detection.
Results
Over a period of 9 months, 99 patients were diagnosed with pulmonary tuberculosis and
subsequently completed sputum culture; they were matched to 196 patients receiving negative
tuberculosis evaluations in the same facilities. Xpert was included in the evaluation of
291 (99%) patients. Compared to culture, Xpert had a sensitivity of 92% (95% confidence
interval 83–97%) and specificity of 95% (92–98%). Twenty patients with negative Xpert
were clinically diagnosed with tuberculosis and subsequently had their culture status determined;
two (10%) were culture-positive. Considering all treated patients regardless of Xpert
and culture data completeness, and considering treatment initiations before a positive Xpert
(N = 4) to be empiric, 26/101 (26%) tuberculosis treatment courses were started empirically. Compared to sputum smear- or Xpert-positive patients with positive cultures, empiricallytreated,
Xpert-negative patients with negative cultures had higher prevalence of HIV (67%
versus 37%), shorter duration of cough (median 4 versus 8 weeks), and lower inflammatory
markers (median CRP 7 versus 101 mg/L).
Conclusion
Judged against sputum culture in a routine care setting of high HIV prevalence, the accuracy
of Xpert was high. Clinical judgment identified a small number of additional culture-positive
cases, but with poor specificity. Although clinicians should continue to prescribe tuberculosis
treatment for Xpert-negative patients whose clinical presentations strongly suggest pulmonary
tuberculosis, they should also carefully consider alternative diagnoses.
Description
Keywords
Empiric treatment, Pulmonary TB, Xpert era, Sputum culture, Xpert MTB/RIF
Citation
Kendall EA, Kamoga C, Kitonsa PJ, Nalutaaya A, Salvatore PP, Robsky K, et al. (2019) Empiric treatment of pulmonary TB in the Xpert era: Correspondence of sputum culture, Xpert MTB/RIF, and clinical diagnoses. PLoS ONE 14(7): e0220251. https://doi.org/10.1371/journal. pone.0220251