Jan 21, 2021; Oxford Academic. https://doi.org/10.1093/ofid/ofab034
We report two cases for whom Xpert MTB/RIF falsely signalled rifampicin-resistant tuberculosis, based on unusually low cycle threshold values (Ct < 10) and three of five probes missing. Other mycobacterial tests were negative. The patients remain well without TB treatment. These erroneous results with grave clinical consequences warrant further optimization of the Xpert MTB/RIF algorithm.