With the exception of non-medicated soaps, every new formulation for hand hygiene should be tested for its antimicrobial efficacy to demonstrate that:
- It has superior efficacy over normal soap; or
- It meets an agreed performance standard
ABHR Performance Testing (in vivo laboratory based tests)
EN 1500 (European Committee for Standardisation
Testing requires 18 – 22 subjects, and a culture of E. coli. Subjects are randomly assigned to two groups where one uses the test handrub, and the other a standard reference solution (60% v/v isopropanol). The groups then reverse roles (cross over design). The mean acceptable reduction with a test formulation shall not be significantly inferior to that with the reference handrub (1).
ASTM E-1174 (ASTM International - used by USA and Canada)
Testing requires two groups of 54 subjects. The indicator organism (S. marcescens or E. coli) is applied and rubbed over hands. The test handrub is then applied. The efficacy criteria are a 2-log10 reduction of the indicator organism on each hand within 5 minutes after the first use, and a 3-log10 reduction of the indicator organism on each hand within 5 minutes after the tenth use (1).
Comparison of ABHR test procedures
The performance criteria in the above tests are not the same, therefore a product could meet one criterion but not the other. The level of reduction in microbial counts needed to produce a meaningful drop in the hand-borne spread of health care associated infections remains unknown (1).
HHA recommends products tested using the EN 1500 criteria as this test more closely reflects the use of an ABHR in a typical clinical situation. The efficacy criteria for the ASTM E-1174 are extremely low, with unmedicated soap and water being able to achieve a 3-log10 reduction of the indicator organism within 1 minute. Furthermore, 5 minutes is too long to wait between patients after using an ABHR (1).