In-Vitro Growth Inhibition of Bacterial Pathogens by Probiotics and a Synbiotic: Product Composition Matters

Abstract

A variety of activities potentially contribute to the beneficial effects of probiotic bacteria observed in humans. Among these is a direct inhibition of the growth of pathogenic bacteria in the gut. The present study characterizes head-to-head the in-vitro pathogen growth inhibition of clinically relevant infectious bacterial strains by different types of probiotics and a synbiotic. In-vitro growth inhibition of <i>Escherichia (E.) coli EPEC, Shigella (Sh.) sonnei, Salmonella (S.) typhimurium, Klebsiella (K.) pneumoniae</i> and <i>Clostridioides (C.) difficile</i> were determined. Investigated products were a yeast mono strain probiotic containing <i>Saccharomyces (Sac.) boulardii</i>, bacterial mono strain probiotics containing either <i>Lactobacillus (L.) rhamnosus GG</i> or <i>L. reuteri DSM 17938</i>, a multi strain probiotic containing three <i>L. rhamnosus strains (E/N, Oxy, Pen)</i>, and a multi strain synbiotic containing nine different probiotic bacterial strains and the prebiotic fructooligosaccharides (FOS). Inhibition of pathogens was moderate by <i>Sac. boulardii</i> and <i>L. rhamnosus GG</i>, medium by <i>L. reuteri DSM 17938</i> and the <i>L. rhamnosus E/N, Oxy, Pen</i> mixture and strong by the multi strain synbiotic. Head-to-head in-vitro pathogen growth inhibition experiments can be used to differentiate products from different categories containing probiotic microorganisms and can support the selection process of products for further clinical evaluation.