pathogens [8,9]. The clinical study demonstrated that L. fermentum
was effective in decreasing intestinal pathogens and increasing ratio
of probiotic bacteria in healthy humans [10]. There ismuch evidence
that has shown that some gastrointestinal lactobacilli ascend to the
vagina. The use of oral formulation of probiotic strains has been
associated with normalization of the vaginal microbiota and local
immune responses [11]. Evidence of fecal and vaginal colonization by
probiotic strains was observed after their oral administration [12].
Oral probiotics can resolve urogenital infections ascending to the
vagina from the rectal area, or by altering the ability of pathogens to
transfer to the vagina [13].
Since probiotic effects on the host are strain specific, it is very
likely that better performing strains may be selected using the
origin of specific strains and a use of the selection process [14].
Before probiotic strains exert their beneficial effects on the host,
they have to be able to survive during passage through the host’s
gastrointestinal tract. They should have high acid and bile tolerance
properties, adherence to host epithelial cells and interference with
the adherence of pathogens, self aggregation and production of
inhibitory substances capable to inhibit the growth of pathogens.
The ability of probiotic strains to adhere to the epithelial surface of
the intestine and vagina and subsequent short or long-term colonization
has always been used as common criteria for selection of
probiotic strains. Enterocyte-like HT-29 and Caco-2 cells have been
successfully used for in vitro studies on the mechanism of cellular
adhesion of probiotics for intestine [15], while HeLa cells have been
used for probiotic bacteria to bind to the vagina [16].
The aim of this study was to investigate the in vitro probiotic
properties of L. fermentum SK5 isolated from a healthy woman’s
vagina that could be used as an oral and vaginal probiotic. This
study focused on its antipathogenic activities, tolerance to simulated
gastrointestinal conditions, adhesion ability and ability to
inhibit adhesion of gastrointestinal and urogenital pathogens to
HeLa, HT-29 and Caco-2 cell lines.