558 JOURNAL OF COSMETIC SCIENCE
results were statistically significant (p 0.05). These data support the test formula’s ability
as a potential makeup remover for cosmetic purposes.
EX VIVO SKIN MICROBIOME EVALUATION
To assess the effect of the skin cleanser prebiotic aqueous micellar solution on the skin
microbiota, an in vitro experiment was conducted utilizing the profiling of two principal
constituents of the human skin microbiome: S epidermidis, a saprophytic bacterium, and S
aureus, a pathogenic bacterium.20
Following a 24-hour incubation period, it was noted that S epidermidis exhibited growth on
the surface of the skin explant (CT1). When S aureus was introduced onto the surface of the
skin explant, which was already covered by a pre-established biofilm of S epidermidis (CT2),
S aureus was capable of colonizing the explant surface, notwithstanding the presence of the
pre-existing S epidermidis biofilm. Upon completion of the incubation period (48 hours), S
epidermidis emerged as the predominant bacterial species (CT2).
In the IP condition in which the prebiotic aqueous micellar solution was administered onto
the preformed S epidermidis biofilm prior to the introduction of S aureus, the population of
S epidermidis and the total bacterial population surpassed what was observed in the CT2
condition. Conversely, the population of S aureus remained lower than CT2. These findings
are illustrated in Figure 3.
According to the results presented (Figure 3), the prebiotic aqueous micellar solution was
able to promote a significant increase of 86% (p 0.1) in the total population of bacteria
(S epidermidis population+S aureus population), as well as a significant increase (p 0.01)
of 99% in the S epidermidis population in the treated skin fragments when compared to
the control. In contrast, there was a significant decrease (p 0.05) of 73% in the S aureus
population in the skin surface treated with the test product when compared to the control.
Figure 3. Growth of the total population of bacteria (including both S epidermidis and S aureus), as well as
the individual populations of S aureus and S epidermidis, measured on the surface of skin fragments treated
with a prebiotic aqueous micellar solution compared to a control. The data were statistically analyzed using
the student’s t-test, with differences between groups considered significant at three levels: p 0.1 (90%
probability), p 0.05 (95% probability), and p 0.01 (99% probability).

559 Prebiotic Micellar Solution
After 7 days of colonization in an antibiotic-free medium, no bacteria have been detected
on the skin explant surface of Group B. This group did not receive incubation treatment
except for a change in the culture medium. Its purpose in the study is to evaluate the
sterility conditions of the skin throughout the experiment to ensure the feasibility and
reliability of the test by observing the growth of unwanted microorganisms that could
mask the results obtained.
Despite their usefulness, skin cleansers’ potential impacts cannot be ignored. Disturbances
caused by hand hygiene practices, including soaps and cleansers, may disrupt protective
mutualisms in the skin microbiota, which allow invaders to colonize.20 In addition,
traditional hygiene practices, including the use of soaps and traditional cleansers, fail to
consider the high abundance of nonharmful and potentially helpful bacteria on the skin,
which may be disrupted by these products.21
S epidermidis, for instance, may act in reverse and prevent the colonization and proliferation
of S aureus in the human nostrils.22 This would make eradicating S epidermidis detrimental
to the host by facilitating the increased colonization of opportunistic pathogens.23 Moreover,
S epidermidis has been shown to produce antimicrobial peptides and modulate the host
immune response, which indicate its potential role in maintaining healthy host/microbiota
relationships.24
S epidermis is integral to maintaining the skin barrier function through the secretion of
sphingomyelinase, which assists the bacteria in nutrient acquisition and facilitates the host’s
production of ceramides. Furthermore, it enhances the expression of proteins related to
ceramide biosynthesis including claudin-1 and occluding.25 These ceramides are vital lipids
that contribute to moisture retention and safeguard the skin against environmental stressors.26
S aureus, in contrast, is the universal cause of boils, carbuncles, and skin abscesses and is
the agent generally identified as responsible for skin and soft tissue infections.27,28 S aureus
infections often begin as minor boils or abscesses and can progress to serious systemic
infections such as bacteremia and sepsis.29 Pre-existing conditions, such as injury (ulcers,
wounds) or tissue inflammation (exudative dermatitis), as well as underlying disorders (such
as diabetes mellitus or poorly controlled insulin-dependent cancer), are some of the risk
factors for infection with S aureus.27
S aureus also has a pivotal position in atopic dermatitis (AD) due to its ability to establish
intricate biofilms that considerably affect the integrity of the skin barrier and the host’s
immune response. The skin colonization by S aureus, especially in its biofilm state, is linked
to antibiotic resistance and dysbiosis, as the increased population of S aureus occurs to the
detriment of resident microbiota such as S epidermidis.30 This dysbiosis, along with the
dominance of S aureus, can intensify AD severity, thus rendering it an essential contributor
to the pathogenesis of the condition.31Therefore, skin cleansers must ensure the removal of
pathogenic microorganisms selectively that is, they must alter the population of commensal
microorganisms as little as possible. One of the ways to maintain the balance of the skin’s
microbiota is by using prebiotics, or ingredients that stimulate the growth and/or activity
of one or a limited number of microorganisms.32
The term prebiotic was initially developed to describe materials (carbohydrates) that reach
the colon when ingested and promote the growth of desirable organisms (probiotics). In
2017, the International Scientific Association for Probiotics and Prebiotics coined the current
definition of prebiotic as “a substrate that is selectively utilized by host microorganisms
conferring a health benefit.”33