Treatment of specimens

In total 2 ml of phosphate-buffered saline (pH 7.4) (Sigma-Aldrich, Milano, Italy) were added to the cervico-vaginal swabs, collected by a rigid cotton-tipped swab applicator (Nuova Aptaca, Cannelli, Italy), and vortexed. Subsequently, the samples were transferred to microcentrifuge tubes (2 ml) and they were stored at −20 °C until processing.

At processing moment, microcentrifuge tubes were centrifuged at rcf = 15 700 g for 15 min at 7 °C. The majority of supernatant was discarded but 200 µl of supernatant was retained to resuspend the pellet.