A modified cup scrub method for assessing the antibacterial substantivity of personal cleansing products.

An improved in vivo method for evaluating the antibacterial substantivity or residual effectiveness of bar soaps and other personal cleansing products is presented. The effectiveness of an antibacterial bar soap containing 1.5% 3, 4, 4'-trichlorocarbanilide (TCC) versus its soap vehicle was evaluated under simulated conditions considered optimal for bacterial growth, proliferation, and possible infection. A washout period to clear the skin of any antimicrobial agents previously used was followed by a treatment period in which the subjects washed one of their forearms with the antibacterial soap and the other forearm with the soap vehicle. Either immediately or 24 hours following the final wash, three test sites on both forearms were inoculated with S. aureus and occluded with Hill Top Chamber patches. At intervals of 30 minutes, two hours and five hours, the patches were removed. The bacteria on the skin were harvested using the Williamson-Kligman scrub technique (1,2) to determine the number of surviving CFUs at each time period. The method successfully demonstrated that sufficient TCC had remained on the skin for 24 hours after the final wash to effectively inhibit the growth of S. aureuso on the skin for as long as five hours after inoculation.

Leg wash protocol to assess the skin moisturization potential of personal cleansing products.

Many personal cleansers claim to provide a skin moisturization benefit, but there has been relatively little discussion in the scientific literature of the clinical methods that provide the basis for such claims. We have developed a leg wash method to assess the dry skin improvement potential of personal cleansing products. The protocol is performed on 'natural' dry leg skin to avoid potential confounds that may result from applying cleansers to soap-damaged skin. Washes are conducted over a period of days or weeks, with visual and instrumental assessments performed at various times throughout the period to characterize products' short-term and cumulative skin effects. Studies conducted with a variety of personal cleansing technologies demonstrate the method's ability to discriminate products on the basis of their dry skin improvement potential. Further, results from a series of eleven leg wash studies conducted with the same treatment pair under different test conditions (time of year, test facility, expert grader) demonstrate the protocol's robustness. The data generated under this protocol show that personal cleansing products differ widely in their ability to improve dry skin. Our results indicate that there is a wide range of efficacy among moisturizing personal cleansing products, with some products delivering a significant dry skin improvement benefit even for periods as long as 24 hours.