Gel nail polish does not have a negative impact on the nail bacterial burden nor on the quality of hand hygiene with an alcohol-based hand rub

Background: The bacterial burden on gel polished (GP) nails, standard polished (SP) nails and unpolished (UP) nails was evaluated before and after hand hygiene (HH) with alcohol-based hand rub. Methods: Three GP nails, two SP nails and five UP nails on both hands were analysed in 46 healthcare workers. Nail length was maintained at ≤2 mm during the study. Nail surface cultures were performed on blood agar plates before and after HH on days 1, 4, 7, 14 and 21 after application. Nail bacterial counts were estimated using a Poisson regression procedure, with nail polish group, participant, hand side, finger, evaluation day, and interaction between nail polish group and evaluation day as independent factors. Results: In total, 460 nails were evaluated: 92 SP nails (20%), 138 GP nails (30%) and 230 UP nails (50%). Before HH, SP nails were associated with a higher bacterial burden than GP nails on day 4, and with a higher bacterial burden than GP nails and UP nails on day 21 (with counts for UP nails higher than those for GP nails). After HH, SP nails had a higher bacterial burden than UP nails and GP nails on day 4, a higher bacterial burden than UP nails on day 14, and a higher bacterial burden than UP nails and GP nails on day 21. Conclusions: Compared with UP nails, GP nails were not associated with a higher bacterial burden within 3 weeks of application, and even had a significantly lower bacterial burden before HH on day 21.