The intake of probiotic lactic acid bacteria not only promotes digestion through the microbiome regulated host intestinal metabolism but also improves diseases such as irritable bowel syndrome and inflammatory bowel disease, and suppresses pathogenic harmful bacteria. This investigation aimed to evaluate the immunomodulatory effects in intestinal epithelial cells and to study the clinical efficacy of the selected the <i>Bifidobacterium breve</i> and <i>Bifidobacterium longum</i> groups. The physiological and biochemical properties were characterized, and immunomodulatory activity was measured against pathogenic bacteria. In order to find out the mechanism of inflammatory action of the eight viable and sonicated <i>Bifidobacterium</i> spp., we tried to confirm the changes in the pro-inflammatory cytokines (TNF-α, interleukin (IL)-6, IL-12) and anti-inflammatory cytokine (IL-10), and chemokines, (monocyte chemoattractant protein-1, IL-8) and inflammatory enzymatic mediator (nitric oxide) against <i>Enterococcus faecalis</i> ATCC 29212 infection in Caco-2 cells and RAW 264.7 cells. The clinical efficacy of the selected <i>B. breve</i> and <i>B. longum</i> group was studied as a probiotic adjuvant for acute diarrhea in children by oral administration. The results showed significant immunomodulatory effects on the expression levels of TNF-α, IL-6, IL-12, MCP-1, IL-8 and NO, in sonicated <i>Bifidobacterium</i> extracts and viable bifidobacteria. Moreover, each of the <i>Bifidobacterium</i> strains was found to react more specifically to different cytokines. However, treatment with sonicated <i>Bifidobacterium</i> extracts showed a more significant effect compared to treatment with the viable bacteria. We suggest that probiotics functions should be subdivided according to individual characteristics, and that personalized probiotics should be designed to address individual applications.

Bifidobacterium strains inhibit growth or cell adhesion of pathogenic bacteria and against multidrug-resistant bacteria. Furthermore, when combined with certain antibiotics, probiotics can boost their antibacterial activity. The objective of present report was to evaluate the antibacterial effect of Bifidobacterium spp. In the first part of the investigation, we evaluated the antibacterial activities of viable and inactivated cells, from a total of 12 Bifidobacterium species, on the growth of three different common pathogens associated with multi-drug resistance such as Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Eenterococcus faecalis. Also, eight strains of sonication-inactivated Bifidobacteria exhibited antibacterial activity against S. aureus and P. aeruginosa. Additionally, eight viable Bifidobacterium strains exhibited antibacterial activity on the growth of pathogenic species. Therefore, we observed the antimicrobial activity, of Bifidobacteria against pathogenic bacteria, on the solid medium utilizing the agar well diffusion method. Some Bifidobacterium supernatants such as B. longum and B. pseudocatenulatum, showed synergism with the antibacterial activity of antibiotics. The results exhort that Bifidobacteria could be employed as an effective control for nosocomial pathogenic bacteria, and reduce the risk of the development of S. aureus and P. aeruginosa infection. The present authors propose that Bifidobacteria might be a useful probiotic microorganism, for combining modality with antibiotics, without adverse effects.