Evaluation of 15-second alcohol-based hand rub efficacy: a multi-laboratory study using a modified EN 1500 protocol

Hands are a key vector for pathogen transmission in healthcare, making effective hand antisepsis crucial for infection prevention. According to the European standard EN 1500, the reference method for evaluating hand antiseptics, a minimum rub-in time of 30 s is required. However, observations show healthcare workers typically spend less time on hand antisepsis.

To assess the feasibility of a reduced rub-in time under standardized conditions, the German Association for Applied Hygiene conducted a multi-centre ring trial in 14 laboratories using a modified EN 1500 protocol (15 s, 3 mL of 60% v/v propan-2-ol). In a randomized crossover design, volunteers' hands were contaminated with Escherichia coli K12 and treated either with the reference (2 × 3 mL/2 × 30 s) or the test protocol (1 x 3 mL/15 s). Microbial reduction was measured and non-inferiority statistically analysed.

The 15-second protocol yielded significantly lower log₁₀ reductions than the reference in 13 out of 14 laboratories but demonstrated consistent reproducibility and satisfactory interlaboratory performance. Challenges in completing the full rub-in technique within 15 s were reported, indicating the need for targeted training.

These findings support the methodological feasibility of a shortened protocol and are consistent with evolving clinical guidelines advocating reduced rub-in times, as well as with real-world practice, where healthcare workers typically spend less than 30 s on hand antisepsis. Nonetheless, any revision of EN 1500 should proceed cautiously to ensure antimicrobial efficacy, emphasizing complete hand coverage and strict adherence to technique.