Antibacterial efficacy of handrubbing for 15 versus 30 seconds: EN 1500-based randomized experimental study with different loads of Staphylococcus aureus and Escherichia coli

Abstract Objectives Compliance with the World Health Organization ‘how to handrub' action is suboptimal. Simplifying the hand-hygiene action may improve practice. However, it is crucial to preserve antibacterial efficacy. We tested the non-inferiority of 15 versus 30 seconds handrubbing for Staphylococcus aureus and Escherichia coli contamination at different loads, using hand-size customized alcohol-based handrub (ABHR) volumes. Methods In an EN1500-based study, 18 health-care workers (HCWs) with extensive experience in hand hygiene rubbed hands with a hand-size customized volume of isopropanol 60% v/v. They repeated the following sequence: hand contamination ( E. coli or S. aureus ; broth containing 10 8 or 10 6  CFU/mL); baseline fingertips sampling; handrubbing (15 or 30 seconds); re-sampling. The main outcome was log 10  CFU corrected reduction factor (cRF) on HCWs' hands, applying a generalized linear mixed model with a random intercept for subject. Results The median cRF was 2.1 log 10 (interquartile range 1.50–3.10). After fitting the model, cRF was significantly higher for S. aureus compared with E. coli but there was no significant effect for duration of handrubbing or contamination fluid concentration. Fifteen seconds of handrubbing was non-inferior to 30 (–0.06 log 10 , 95% CI –0.34 to 0.22; EN1500 0.60 log 10 non-inferiority margin). This was confirmed in all pre-specified subgroups. Conclusion Among experienced HCWs using a hand-size customized volume of ABHR, handrubbing for 15 seconds was non-inferior to 30 seconds in reducing bacterial load, irrespective of type of bacteria or contamination fluid concentration. This provides further support for a shorter, 15-seconds, hand-hygiene action.