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Comparative efficacy of commercially available alcohol-based handrubs and WHO-recommended handrubs: which is more critical, alcohol content or product formulation?

BACKGROUND/OBJECTIVES: Alcohol-based hand rubs (ABHR) are the primary form of hand hygiene in healthcare settings globally. Alcohol level in many products outside the US tends to be higher than those in the US. The formulations provided in the World Health Organization (WHO) Guidelines on Hand Hygiene contain either 80% ethanol or 75% isopropanol. Recent studies have further suggested that foaming alcohol-based products deliver inferior efficacy compared to other product formats (i.e. gels / liquids). The objective of this study was to determine the relative importance of alcohol concentration alone versus product formulation and format as drivers for antimicrobial efficacy. METHODS: Three commercial products were evaluated: two recently introduced novel ABHRs, Product A (70% v/v ethanol gel) and Product B (70% v/v ethanol foam); and Product C, an ABHR gel (85% w/w ethanol (90% v/v)). WHO-recommended hand rub formulations were included as benchmarks: WHO-EtOH (80% v/v ethanol) and WHO-IPA (75% v/v isopropanol). Test articles were evaluated on the hands of adult subjects at a 2 ml dose using the Health Care Personnel Handwash (HCPHW) method according to US FDA requirements. Log reductions from baseline were calculated after one and ten product applications. Statistical analysis was conducted using one-way ANOVA (a50.05). RESULTS: Log reductions for Products A, B, C, WHO-EtOH, and WHO-IPA were 3.58, 3.55, 3.12, 3.07, and 3.12, respectively after one application; and were 3.50, 4.00, 2.39, 2.04, and 1.80, respectively after the tenth application. After one application Product A was statistically superior to Product C, WHO-EtOH, and WHO-IPA; and Product B was superior to WHO-EtOH (p,0.05). After ten applications Products A and B were statistically superior to Product C, WHO-EtOH, and WHO-IPA (p,0.001). CONCLUSIONS: Products A and B were the only test articles to meet the FDA HCPHW requirement of a 3 log reduction after the tenth application. Product formulation was found to be the key determinant of product efficacy, as well formulated 70% ethanol formulations were statistically superior to products with higher alcohol levels. These results demonstrate that alcohol concentrations in excess of 70% are neither necessary nor sufficient for efficacy. Finally, these results demonstrate that product format (foam vs. gel or rub) is not a key determinant of efficacy; when properly formulated, ABHR foams can meet efficacy requirements. American Journal of Infection Control. 2011;39(5):e19-e20.

Author: Edmonds S, Macinga D, Mays-Suko P

Published: 01/01/2011

Publication Type: Journal article

Publisher: American Journal of Infection Control.