Cosmetic Wipe Sample Preparation for Microbiological Analysis—Single Laboratory Validation Study

Cosmetic wipes are made for multiple functions, baby care, hand washing, feminine and personal cleansing, removing makeup, and applying products such as deodorants and sunless tanners among other uses. Despite the presence of preservatives, cosmetic wipes can become contaminated during processing steps and usage, which may lead to skin infections and other health issues for consumers. No validated method exists for the microbiological testing of cosmetic wipes. The goal of this study was to develop and validate a specific sample preparation method for the quantitative detection of microorganisms in cosmetic wipes for inclusion in the FDA Biological Analytical Manual (BAM). Ten wipe types differing in their composition and preservative combinations were inoculated with Bacillus cereus spore suspensions at three concentration levels and aged for 14 days. Three extraction methods were compared: mBAM1g (reference method using 1 g samples), mBAMww (whole wipe method based on BAM Chapter 23), and ISOww (whole wipe method based on ISO method without Tween 80). For commercial wipes, mBAMww and ISOww, using whole wipes, performed similarly (p ≥ 0.05) or significantly better (p < 0.05) than mBAM1g. For laboratory-made wipes, 1 g samples showed higher recovery rates than whole wipes, likely due to cell loss during aging. Inoculation method and preservatives affect microbial distribution, survival, and recovery rates. T80 may have a positive effect on the recovery of B. cereus from wipes. This study recommends mBAMww for the microbiological analysis of cosmetic wipes.