ESwab challenges influenza virus propagation in cell cultures.

Although the ESwab kit (Copan, Brescia, Italy) is intended for sampling bacteria for culture, this kit is increasingly also used for virus sampling. The effect of ESwab medium on influenza virus detection by real-time reverse transcription-polymerase chain reaction (RT-PCR) or virus propagation in Madin-Darby canine kidney (MDCK) cell culture was investigated. The ESwab medium was suitable for viral RNA detection but not for viral propagation due to cytotoxicity. Sampling influenza viruses with ESwab challenges influenza surveillance by strongly limiting the possibility of antigenic characterisation.