J. Cosmet. Sci., 65, 89–101 (March/April 2014) 89 In vitro evaluation of carboxymethylcellulose effectiveness in releasing Candida albicans from skin strips DAVID W. KOENIG, Corporate Research & Engineering, Kimberly-Clark Corporation, Neenah, WI 54957. Accepted for publication March 10, 2014. Synopsis Development of more effective products for cleansing the skin of microorganisms is enhanced by improved understanding of the mechanisms of attachment, as well as potential removal strategies. This paper de- scribes an in vitro method for use of the cationic exchanger carboxymethylcellulose (CMC) to enhance the removal of the yeast Candida albicans as measured in vitro using human skin tape strippings. Several nega- tively charged and cationic exchanger compounds were evaluated using a visual release method to determine their ability to prompt release of C. albicans from human skin strips. CMC was further tested using a viable count method to assess its ability to effectively release the yeast from skin strips and to evaluate the effects of pH on CMC performance. CMC microparticles were found to release greater than 95% of bound C. albicans from the skin strips over a broad range of pH values. Interaction of CMC with the overall skin charge appears to result in detachment of C. albicans, a response suggesting that anionic particles may facilitate C. albicans removal from skin. INTRODUCTION Microorganisms attach to the skin through multiple mechanisms (1–4) and are frequently removed through complex physical cleaning strategies that combine surfactant action, shear forces, and affi nity binding. Understanding mechanisms of microbial attachment to skin facilitates the design of physical cleaning products and compounds that counteract attachment forces, thereby freeing soils and microbes from the skin surface. In addition to the bacterial pathogens commonly encountered through fecal contact, approximately 30% of the general population, primarily women, suffer from health conditions caused by yeast and fungi (5–7). The fungi represent a diverse, heterogeneous group of eukaryotes. Of the estimated one million species of fungi, molds, and yeasts, only about 50 are considered pathogenic (6,8). Most are opportunistic pathogens, becoming more prevalent during periods of stress or lowered immune response. Yeasts from the genus Candida are spread through contact with feces and secretions from the mouth, nose, skin, and vagina. Although normally Address all correspondence to David W. Koenig at dwkoenig@kcc.com.

JOURNAL OF COSMETIC SCIENCE 90 noninfective and present in small numbers, Candida can multiply under some circum- stances and cause symptoms requiring medical treatment. Circumstances that promote Candida infection include hormonal changes (5,9,10), medication side effects (5,11), and medical conditions (5,7). The human body inhibits fungal growth through intact skin and other protective mech- anisms, such as naturally occurring long-chain unsaturated fatty acids, pH, competition with normal bacterial fl ora, epithelial turnover, and the desiccated nature of the stratum corneum (11). Other body systems such as the respiratory tree, gastrointestinal tract, and vaginal vault are lined with mucous membranes (epithelium) bathed in antimicrobial fl uids, and some are also lined with ciliated cells that actively remove foreign materials (8,12). Only when these protective barriers are breached can fungi gain access to, colo- nize, and multiply within host tissues. Candidiasis is a primary or secondary mycotic infection caused by Candida, often by the most common Candida species, Candida albi- cans (9). Candida is a dimorphic organism with the ability to convert between the yeast and mycelial fungal forms (10,13). The yeast form is a noninvasive sugar-fermenting or- ganism. The mycelial fungal form produces long root-like invasive hyphae that penetrate the mucosa or skin (14). Vaginitis, thrush (oral candidiasis), esophagitis, gastrointestinal candidiasis, cutaneous candidiasis, diaper rash, paronychia (nail fold infection), and chronic mucocutaneous can- didiasis are all conditions caused by Candida (5,7,8). The clinical manifestations may be acute, subacute, chronic, or episodic. The etiology can be very diffi cult to determine be- cause Candida spp. are commonly recovered from healthy people (5–7,9). Candida has also been implicated as a frequent cause of infant diaper rash (5,7,8). Diaper rash usually begins as a solid patch of red, thickened skin, often around the anus, that can spread to cover the entire groin and lower buttocks. The same moist, warm, closed-off conditions triggering the original rash can also result in skin infection by the yeast. An infected rash can appear as a group of distinct round spots characterized by oozing, crust- ing, or surrounding redness and swelling. Treatment of candidiasis almost always requires the use of antibiotics (11), which can result in the production of antibiotic resistant yeast, extended discomfort until the treat- ment achieves maximum effectiveness, and possibly harmful side effects due to pharma- ceutical toxicity or allergies (11). Therefore, the development of effective physical methods of preventing or treating yeast infections without the use of antibiotics or anti- microbials is highly desirable. Technologies that interfere with the attachment to and invasion of the skin by yeast offer a promising strategy for physical control of yeast activ- ity and prevention of related skin conditions. Candida attaches to skin by three primary mechanisms: hydrophobic interaction (15), electrostatic interaction (4), and ligand interaction (4,12). These reactions may occur independently or in combination at any given moment during substrate interaction (1,15–17). Innovative strategies for disruption of yeast attachment mechanisms, which require a comprehensive understanding of yeast–skin interactions, are essential to the development of improved personal care products. Hydrophobic interactions are weak chemical bonds formed through repulsion of insol- vent molecules by water (18–20), mainly resulting from convergence of nonpolar side chains away from water (18). Hydrophobic interactions promote adherence of Candida to skin (12,15,21) and despite the weak nature of these bonds, their cumulative effect can