The effects of test variables on the efficacy of hand hygiene agents

Hand hygiene is essential to interrupting disease transmission in health care facilities. Multiple hand hygiene agents are currently available for use in the health care setting. To evaluate the utility of these agents, both the user acceptability and the efficacy need to be evaluated. Different hand hygiene test methodologies have been used to measure the efficacy of these agents, but efficacy results vary depending on variations to key parameters in these methodologies. The purpose of this study was to evaluate the effect of test variables on the efficacy of hand hygiene agents.

Both a comprehensive literature review and original hand hygiene efficacy studies were undertaken. The literature review was conducted using a Medline search, and hand hygiene efficacy studies were conducted under the American Society for Testing and Materials (ASTM). E 1174 Standard Test Method for Evaluation of the Effectiveness of Health Care Personnel Handwash Formulation.

The literature review and our original data showed that the following variables affected the hand hygiene efficacy measurements: hand jewelry, experimental contamination versus normal flora, method of application of test organism, hand hygiene agent, concentration of active ingredient, volume of hand hygiene agent, duration of application of hand hygiene agent, method of application of hand hygiene agent, and study method (human challenge trial versus in vitro suspension test).

Although many methodological variables affect efficacy results, infection control professionals in their analysis of product information should always assess the results in light of the following key variables: concentration and type of active ingredient, duration of exposure to hand hygiene agent, volume of hand hygiene agent applied, test organism, and study method (ie, human challenge vs. in vitro suspension test).