Performance of the Xpert™ Mpox PCR assay with oropharyngeal, anorectal, and cutaneous lesion swab specimens

• Published in: Journal of clinical virology 2024-04, Vol.171, p.105659, Article 105659
• Main Authors: Damhorst, Gregory L., McLendon, Kaleb, Morales, Evelyn, Solis, Zianya M., Fitts, Eric, Bowers, Heather B., Sabino, Courtney, Sullivan, Julie, Greenleaf, Morgan, Roback, John D., Colasanti, Jonathan A., Sheth, Anandi N., Titanji, Boghuma K., Martin, Greg S., Bassit, Leda, Lam, Wilbur A., Rao, Anuradha
• Format: Article
• Language: English
• Subjects: Anorectal swab; Diagnostic; Humans; Mpox; Mpox (monkeypox); Oropharyngeal swab; Point-of-care; Polymerase Chain Reaction; Prospective Studies; Sensitivity and Specificity; Sexually transmitted infections; Specimen Handling; United States
• ISSN: 1386-6532; 1873-5967; 1873-5967
• DOI: 10.1016/j.jcv.2024.105659

•Detection of mpox virus at mucosal sites will be critical in any future outbreak.•The Xpert® Mpox assay is one of two CLIA-waived assays with FDA EUA.•Oropharyngeal, anorectal and cutaneous lesion swabs were tested.•We included 20 patients with suspicion for cutaneous mpox, 10 were confirmed cases.•The Xpert® had 100 % positive agreement with our reference assay across sample types.•5 of 5 oropharyngeal and 7 of 8 anorectal specimens spiked at 2x LOD were detected. Anorectal and oropharyngeal exposures are implicated in sexual transmission of mpox, but authorized assays in the United States are only validated with cutaneous lesion swabs. Diagnostic assays for anorectal and oropharyngeal swabs are needed to address potential future outbreaks. The Cepheid Xpert® Mpox is the first point-of-care assay to receive FDA emergency use authorization in the United States and would be a valuable tool for evaluating these sample types. Our exploratory study demonstrates 100 % positive agreement with our in-house PCR assay for natural positive anorectal and oropharyngeal specimens and 92 % sensitivity with low-positive spiked specimens. The Xpert® assay detected viral DNA in specimens not detected by our reference PCR assay from four participants with mpox DNA at other sites, suggesting it may be more sensitive at low viral loads. In conclusion, the validation of the Xpert® for oropharyngeal and anorectal sample types can be rapidly achieved if clinical need returns and prospective samples become available.