A comparison of ThinPrep against four non-volatile transport media for HPV testing at or near the point of care

Abstract

The Xpert HPV Test is used at point of care for cervical screening in a number of low and middle income countries (LMIC). It is validated for use with ThinPrep-PreservCyt transport medium which has a high methanol content and is therefore classified as a dangerous good for shipping, making cost, transportation and use challenging within LMIC. We compared the performance of ThinPrep against four non-volatile commercially available media for human papillomavirus (HPV) point of care testing. Ten-fold serial dilutions were prepared using three HPV cell lines each positive for 16, 18 or 31 and with each suspended in five different media types. The media types consisted of Phosphate Buffered Saline (ThermoFisher Scientific, USA), Sigma Virocult (Medical Wire and Equipment, UK), MSwab (Copan, Italy) Xpert Transport Media (Cepheid, USA) and ThinPrep-PreservCyt (Hologic, USA). A total of 105 Xpert HPV tests were conducted in a laboratory setting, with seven 10-fold dilutions of each of the three HPV genotypes tested in all five media types. The lowest HPV 10-fold dilution detected for any media, or cell line was the fifth dilution. MSwab was the only medium to detect HPV to the fifth dilution across all three cell types. MSwab transport media may be a suitable alternative to ThinPrep for Xpert HPV point of care testing. A field based, head to head comparison of both media types using the Xpert HPV assay is warranted to confirm these laboratory based findings.