Evaluation of the diagnostic accuracy and analytical sensitivity of the novel Xpert® Mpox (Cepheid®) and STANDARD™ M10 MPX/OPX (SD Biosensor) molecular point-of-care assays for the detection of Mpox virus in skin lesion swabs and upper-respiratory swab samples

Abstract

ObjectivesEvaluation of diagnostic accuracy of two point-of-care (POC) molecular diagnostic tests for the detection of monkeypox virus (MPXV): Xpert® Mpox (Cepheid, Inc., USA) and STANDARD™ M10 MPX/OPX (SD Biosensor, Inc., Korea).MethodsDiagnostic accuracy of both platforms was evaluated using 53 upper-respiratory swabs (URS) and 32 skin lesions swabs (SS) collected from mpox and COVID-19 patients in the UK against the Sansure (Sansure Biotech Inc.) and the CDC reference qPCR tests. The analytical sensitivity of both platforms was assessed using a viral isolate from the lineage II, B.1.ResultsThe limit of detection was 1×101pfu/ml for both tests. The overall sensitivity and specificity of the Xpert® Mpox was 97.67% [95% CI 87.71–99.94%] and 88.57% [95% CI 73.26–96.80%] and 97.44% [95% CI 86.52–99.94%] and 74.42% [95% CI 58.83–86.48%] comparing the Sansure and CDC qPCR, respectively and for the M10 MPX/OPX was 87.80% [95% CI 73.80–95.92%] and 76.60% [95% CI 61.97–87.70%] and 94.29% [95% CI 80.84–99.30%] and 86.67% [95% CI 73.21–94.95%] with the Sansure and CDC qPCR.ConclusionThe Xpert® Mpox had good diagnostic accuracy for both sample types while the M10 MPX/OPX clinical accuracy was deficient with URS. Our data supports the use of URS during the first 3 days of symptoms onset for mpox diagnosis.HighlightsThe Xpert® Mpox detected Monkeypox virus (MPXV) DNA in more samples than the M10 MPX/OPX, CDC qPCR and Sansure qPCR suggesting higher sensitivity at lower viral loads.Xpert® Mpox fulfilled the performance requirements recommended in the World Health Organisation (WHO) target product profile (TPP) using upper-respiratory swabs (URS) and skin lesion swabs (SS) but M10 MPX/OPX performance was only met when using SS.MPXV DNA was reliably detectable in SS up to 5 days after onset of symptoms. with all PCR testsThe use of URS for mpox diagnosis is not recommended for use more than 3 days after onset of symptoms.