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: We evaluated the microbial burden on gel polished nails (GPN), standard polished nails (SPN) and unpolished nails (UPN) before and after an alcohol-based hand rub (HHAB).

Methods: Three GPN, two SPN and five UPN in both hands were analyzed in 46 health-care workers volunteers. Nail length was maintained ≤2mm during the study. Nail surface cultures were performed on blood agar plates before and after HHAB on days +1, +4, +7, +14, +21 after application. Nail bacterial counts were estimated by a Poisson regression procedure, using polish group, participant individual, hand side, finger, evaluation day and the interaction between nail polish group and evaluation day as independent factors.

Results: 460 nails were evaluated, 92 SPN (20%), 138 GPN (30%) and 230 UPN (50%). Before HHAB, SPN were associated with a higher bacterial count than GPN on day 4 and with a higher burden than GPN and UPN on day 21 (with counts in UPN higher than in GPN). After HHAB, SPN was associated with a higher bacterial count than UPN and GPN on day 4, than UPN on day 14, and than UPN and GPN on day 21.

Conclusions: Compared with UPN, GPN were not associated with a higher bacterial burden within 3 weeks after application, and even had a significant lower count on day 21 before HHAB.