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. 2016 Jun;8(6):1205-9.
doi: 10.21037/jtd.2016.04.19.

The reliability analysis of Xpert-positive result for smear-negative and culture-negative specimen collected from bone and joint tuberculosis suspects

Guomei Wei  1 , Jing Mu  1 , Guirong Wang  1 , Fengmin Huo  1 , Lingling Dong  1 , Yunxu Li  1 , Hairong Huang  1
Affiliations

The reliability analysis of Xpert-positive result for smear-negative and culture-negative specimen collected from bone and joint tuberculosis suspects

Guomei Wei et al. J Thorac Dis. 2016 Jun.

Abstract

Background: The Xpert MTB/RIF assay (Xpert; Cepheid, Sunnyvale, CA, USA) has been widely used for pulmonary and extra-pulmonary tuberculosis (TB) diagnosis. In clinical practice, specimen yielding smear-negative, culture-negative but Xpert-positive results is frequently confronted. Due to the notorious possibility of contamination that molecular tests always been thought of, Xpert-positive results without bacteriological supporting evidence arouse great confusions to clinicians.

Methods: A retrospective study was performed. From April 2014 to February 2015, 852 clinical specimens were Xpert-positive. The results of Xpert assay, bacteriological and pathological examinations from either the same specimens or from the specimens collected during same clinical operations were investigated.

Results: A total of 90 specimens with Xpert-positive but smear-negative and culture-negative results were recruited, and 81 of them were pus specimens collected from Bone and Joint Tuberculosis (BJTB) patients. According to the pathological examination results, 77 of the 81 pus specimens, 8 of 9 other types of specimens were confirmed as either TB or strongly suggestive of TB; three pus specimens and one biopsy tissue were also suggested TB but with less stronger evidence; only one pus specimen was not TB suggestive.

Conclusions: Our study demonstrated that Xpert could be trusted for BJTB diagnosis even when no supporting bacteriological evidence is available in high TB prevalence settings. Our results will alleviate the confusion among clinicians in such scenarios.

Keywords: Xpert MTB/RIF assay; pathological examination; tuberculosis (TB).

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Conflict of interest statement

Conflicts of Interest: The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Flow diagram outlining patient enrollment and stratification for the evaluation of Xpert.
See this image and copyright information in PMC

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