Following test method may help you in establishing the quality parameters to test the effectiveness of the antimicrobial properties of your soap samples
10.1.1. Methods to test activity of hygienic handwash and handrub agents
The following in vivo methods use experimental contamination to test the capacity of a formulation to reduce the level of transient microflora on the hands without regard to the resident flora. The formulations to be tested are hand antiseptic agents intended for use by HCWs, except in the surgical area.
CEN standards: EN 1499 and EN 1500
In Europe, the most common methods for testing hygienic hand antiseptic agents are EN 1499200 and EN 1500.201Briefly, the former standard requires 12–15 subjects, and the latter (in the forthcoming amendment) 18–22, and a culture of E. coli. Subjects are assigned randomly to two groups where one applies the test formulation and the other a standardized reference solution. In a consecutive run, the two groups reverse roles (cross-over design).
If an antiseptic soap has been tested according to EN 1499,200 the mean log10 reduction by the formulation must be significantly higher than that obtained with the control (soft soap). For handrubs (EN 1500), the mean acceptable reduction with a test formulation shall not be significantly inferior to that with the reference alcohol-based handrub (isopropyl alcohol or isopropanol 60% volume).
Currently, handwash or handrub agents are evaluated using this method in North America. The efficacy criteria of the FDA’s Tentative Final Monograph (TFM) 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.198
The performance criteria in EN 1500 and in the TFM for alcohol-based handrubs are not the same.48,198,201
Therefore, a formulation may pass the TFM criterion, but may not meet that of EN 1500 or vice versa.203
It should be emphasized here that the level of reduction in microbial counts needed to produce a meaningful drop in the hand-borne spread of nosocomial pathogens remains unknown.48,204
ASTM E-1838 (fingerpad method for viruses)205
The fingerpad method can be applied with equal ease to handwash or handrub agents. When testing handwash agents, it can also measure reductions in the levels of viable virus after exposure to the test formulation alone, after post-treatment water rinsing and post-rinse drying of hands. This method also presents a lower risk to subjects because it entails contamination of smaller and well-defined areas on the skin in contrast to using whole hands (see below). The method can be applied to traditional as well as more recently discovered viruses such as caliciviruses.206
ASTM E-2276 (fingerpad method for bacteria)207
This method is for testing handwash or handrub against bacteria. It is similar in design and application to the method E-1838205
described above for working with viruses.
ASTM E-2613 (fingerpad method for fungi)208
This method is for testing handwash or handrub against fungi. It is similar in design and application to the methods described above for working with viruses (E-1838)205
and bacteria (E-2276).207
ASTM E-2011 (whole hand method for viruses)209
In this method, the entire surface of both hands is contaminated with the test virus, and the test handwash or handrub formulation is rubbed on them. The surface of both hands is eluted and the eluates assayed for viable virus..
to read the full detail visit
WHO Guidelines on Hand Hygiene in Health Care: First Global Patient Safety Challenge Clean Care Is Safer Care.
Dr Humaid Khan
MD Halal International services