A growing body of clinical and experimental data supports the view that the efficacy
of probiotics is strain-specific and restricted to particular pathological conditions,
which means that newly isolated probiotic strains need to be targeted to a specific
disease. Following national and international guidelines, we used a conventional in vitro
experimental approach to characterize a novel strain of Lactobacillus reuteri, LMG P-
27481, for safety (sensitivity to antibiotics and genome analysis) and putative efficacy
(resistance to gastro-intestinal transit, adhesiveness, induction of cytokines, and release
of antimicrobial metabolites). In vitro assays, which were carried out to examine the
probiotic’s effect on diarrhea (lactose utilization, inhibition of pathogens such as bacteria
and Rotavirus), showed that it was more efficacious with respect to well-known
reference strains in antagonizing Clostridioides difficile (CD). Data confirming that the
probiotic can effectively treat CD colitis was gained from in vivo trials involving mice
conditioned with large spectrum antibiotics before they were subjected to CD challenge.
Two out of the three antibiotic-treated groups received daily LMG P-27481 for different
time durations in order to simulate a preventive approach (LMG P-27481 administered
prior to CD challenge) or an antagonistic one (LMG P-27481 administered after
CD challenge). Both approaches significantly reduced, with respect to the untreated
controls, CD DNA concentrations in caecum and C. difficile toxin titers in the gut lumen.
In addition, LMG P-27481 supplementation significantly mitigated body weight loss and
the extent of inflammatory infiltrate and tissue damage. The study results, which need
to be confirmed by in vivo clinical trials, have demonstrated that the L. reuteri LMG
P-27481 strain is a promising probiotic candidate for the treatment of CD infection.