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. 2021 Jan 21;8(2):ofab034.
doi: 10.1093/ofid/ofab034. eCollection 2021 Feb.

Low Cycle Threshold Value in Xpert MTB/RIF Assay May Herald False Detection of Tuberculosis and Rifampicin Resistance: A Study of Two Cases

Jean Claude S Ngabonziza  1   2   3 , Tom Decroo  4   5 , Rodrigue Maniliho  6 , Yves M Habimana  7 , Armand Van Deun  8 , Bouke C de Jong  2
Affiliations

Low Cycle Threshold Value in Xpert MTB/RIF Assay May Herald False Detection of Tuberculosis and Rifampicin Resistance: A Study of Two Cases

Jean Claude S Ngabonziza et al. Open Forum Infect Dis. .

Abstract

We report 2 cases for whom Xpert MTB/RIF falsely signaled rifampicin-resistant tuberculosis, based on unusually low cycle threshold and 3 of 5 probes missing. Other mycobacterial tests were negative. Further optimization of the Xpert MTB/RIF algorithm is warranted.

Keywords: Xpert MTB/RIF assay; active case finding; false detection of TB; rifampicin resistance.

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Figures

Figure 1.
Figure 1.
False signals for detection of tuberculosis (TB) and/or rifampicin resistance results. (A) Test report of false TB detection showing low probe cycle threshold (Ct) values and jagged amplification curves. (B) Test report of false TB detection showing low probe Ct values and straight lines instead of standard polymerase chain reaction amplification curves. (C) Test report of false rifampicin resistance showing low probe Ct values and amplification curves. (D) Test report of false rifampicin resistance showing a low Ct value for probe E.
Figure 1.
Figure 1.
False signals for detection of tuberculosis (TB) and/or rifampicin resistance results. (A) Test report of false TB detection showing low probe cycle threshold (Ct) values and jagged amplification curves. (B) Test report of false TB detection showing low probe Ct values and straight lines instead of standard polymerase chain reaction amplification curves. (C) Test report of false rifampicin resistance showing low probe Ct values and amplification curves. (D) Test report of false rifampicin resistance showing a low Ct value for probe E.
See this image and copyright information in PMC

References

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