ASTM E1327-07 (2018). Standard Test Method for Evaluation of Antimicrobial Handwash Formulations by Utilizing Fingernail Regions. 

Test accredited by ENAC (Spanish National Accreditation Entity).

Test with the certificate of Good Laboratory Practices (GLPs).

This test aims to evaluate the effectiveness of antimicrobial agents for handwashing, including handrub, in the reduction of transient bacterial flora with specific emphasis on the nail region. Volunteer subjects, unlike to other guidelines methods, do not need to obviate from using topical antimicrobials before participating in the study, but only wash their hands with a non-antimicrobial hand soap before the test to remove any residual hands lotion and reduce the resident flora of the skin. For each subject, although up to 10 test replicas could be obtained, however, the guideline recommends three replicas using only the ring, middle and index fingers. Serratia marcescens and Escherichia coli must be used as marker organism, whereas a spore suspension of Bacillus subtilis may be utilized to study the degree of physical removal by handwashing techniques and the recovery and precision aspects of the test method.

The test product is evaluated by placing the organism in the region surrounding the cuticle and under the three-finger nails of the left hand of each volunteer, allowing the test suspension to dry. The reference substance (controls) included in the test corresponds to a non-antimicrobial soap. Another control includes a group of non-treated volunteers. After the contamination with the test organism, a handwashing and subsequent rinsing is carried out. For the liquid antimicrobial soap test formulation, the instructions indicated by the manufacturer with subsequent handwashing will be followed without drying them. In case of alcoholic formulations, a known volume is placed, indicated by the manufacturer, and the hands are rubbed until the alcohol has evaporated. After performing the procedure with both, the reference product and the test product, each nail will be rubbed with a brush in a Petri dish containing a sampling solution. In the case of those test substances that do not require a subsequent handwashing, after nail contamination, the nails are rubbed directly with the brush.

The activity of the products is evaluated by comparing the number of bacteria recovered from regions of artificially contaminated nails after the use of hand washing formulations with respect to the number recovered from the regions of artificially contaminated nails but treated with a non-antimicrobial reference product. The results obtained in the plate counts (CFU/finger) are averaged and the log10 of the reductions are determined in each case, re-evaluated by a statistical method.

According to the Standard, in our laboratory we will analyse 15 volunteers. Each person will perform the test with one variable on each of the 3 test days, of three consecutive weeks (unwashed hands determinations, testing nonantimicrobial soap and testing antimicrobial formulation).

The client must choose the contact time, the concentration and quantity of product in the test or indications on how to add the product. The applicant for the test must state these requirements on the test submission form.