Lacticaseibacillus rhamnosus GG inhibits infection of human keratinocytes by Staphylococcus aureus through mechanisms involving cell surface molecules and pH reduction

Beneficial bacteria represent an emerging tool against topical diseases, including infection caused by Staphylococcus aureus. Here, we investigated several anti-pathogenic mechanisms of the model probiotic Lacticaseibacillus rhamnosus GG against a clinical S. aureus isolate by implementing various mutants lacking important cell surface molecules. We analysed adhesion of L. rhamnosus and competitive adhesion with S. aureus to primary human keratinocytes, L. rhamnosus and S. aureus auto- and co-aggregation, S. aureus growth inhibition, keratinocyte viability increase, and monocyte Toll-like receptor (TLR) activation by L. rhamnosus as such, or with S. aureus. L. rhamnosus mutated in SpaCBA pili exhibited reduced adhesion to keratinocytes, reduced ability to prevent S. aureus adhesion to keratinocytes and reduced co-aggregation with S. aureus. Mutants in cell wall exopolysaccharides showed enhanced adhesion to keratinocytes and TLR activation in monocytes, suggesting involvement of additional cell surface molecules masked by exopolysaccharides. All L. rhamnosus strains inhibited S. aureus growth, likely due to acidification of the medium. Live (but not UV-inactivated) L. rhamnosus significantly reduced inflammatory TLR activation in monocytes by S. aureus. These data suggest the key role of SpaCBA pili and additional contribution of other cell surface molecules as well as secreted components of L. rhamnosus GG in the multifactorial inhibition of S. aureus adhesion and toxicity in the skin niche.

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

Background: Campylobacter spp. are a major cause of bacterial food-borne diarrhoeal disease. This mainly arises through contamination of meat products during processing. For infection, Campylobacter spp. must adhere to epithelial cells of the mucus layer, survive conditions of the gastrointestinal tract, and colonise the intestine of the host. Addition of probiotic bacteria might promote competitive adhesion to epithelial cells, consequently reducing Campylobacter jejuni colonisation. Effect of Lactobacillus spp. (PCS20, PCS22, PCS25, LGG, PCK9) on C. jejuni adhesion, invasion and translocation in pig (PSI cl.1) and chicken (B1OXI) small-intestine cell lines, as well as pig enterocytes (CLAB) was investigated.Results Overall, in competitive adhesion assays with PSI cl.1 and CLAB cell monolayers, the addition of Lactobacillus spp. reduced C. jejuni adherence to the cell surface, and negatively affected the C. jejuni invasion. Interestingly, Lactobacillus spp. significantly impaired C. jejuni adhesion in three-dimensional functional PSI cl.1 and B1OXI cell models. Also, C. jejuni did not translocate across PSI cl.1 and B1OXI cell monolayers when co-incubated with probiotics. Among selected probiotics, Lactobacillus rhamnosus LGG was the strain that reduced adhesion efficacy of C. jejuni most significantly under co-culture conditions.Conclusion The addition of Lactobacillus spp. to feed additives in livestock nutrition might be an effective novel strategy to targets Campylobacter adhesion to epithelial cells, and thus prevents colonisation, reduces the transmission, and finally lowers the incidence of human campylobacteriosis.

Potential of Lactobacillus casei shirota’s strain against the biofilm-forming of Salmonella Spp

Biofilm of Salmonella spp. is formed through the expression of biofilm genes associated with proteins (bapA) regulated by curli synthesis genes (csg) which carry out adhesion, colonization, maturation, and dispersion on the surface of the intestinal epithelium. This study aimed to determine the antibiofilm activity of Lactobacillus casei Shirota’S strain (LcS) as an inhibitor of Salmonella spp. biofilm formation in vitro. This research was a true experimental study using Microtiter Plate 96 wells Biofilm Assay method. The sample used was the suspension of Salmonella spp. The treatment was in the form of adding a LcS suspension with a concentration series of 10-1;10-2; 10-3;10-4; and 10-5. Biofilm measurements were carried out using a microplate reader and obtained quantitative data in the form of Optical Density at a wavelength of 595nm. The results of this study showed that LcS suspension has antibiofilm activity ranging from 10-5 concentrations with a percentage of 36.58% (p<0.05). The results of exometabolism LcS can reduce Salmonella growth. Exopolysaccharide (EPS) and sortase-dependent proteins (SrtA) of LcS form barriers as competitive adhesion in inhibiting pathogenic biofilm formation.

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

Background: Campylobacter spp. are a major cause of bacterial food-borne diarrhoeal disease. This mainly arises through contamination of meat products during processing. For infection, Campylobacter spp. must adhere to epithelial cells of the mucus layer, survive conditions of the gastrointestinal tract, and colonise the intestine of the host. Addition of probiotic bacteria might promote competitive adhesion to epithelial cells, consequently reducing Campylobacter jejuni colonisation. Effect of Lactobacillus spp. (PCS20, PCS22, PCS25, LGG, PCK9) on C. jejuni adhesion, invasion and translocation in pig (PSI cl.1) and chicken (B1OXI) small-intestine cell lines, as well as pig enterocytes (CLAB) was investigated.Results Overall, in competitive adhesion assays with PSI cl.1 and CLAB cell monolayers, the addition of Lactobacillus spp. reduced C. jejuni adherence to the cell surface, and negatively affected the C. jejuni invasion. In addition, Lactobacillus spp. significantly impaired C. jejuni adhesion in three-dimensional functional PSI cl.1 and B1OXI cell models. Also, C. jejuni did not translocate across PSI cl.1 and B1OXI cell monolayers when co-incubated with probiotics. Among selected probiotics, L. rhamnosus LGG was the strain that reduced adhesion efficacy of C. jejuni most significantly under co-culture conditions.Conclusion The addition of Lactobacillus spp. to feed additives in livestock nutrition might be an effective novel strategy that targets Campylobacter adhesion to epithelial cells, and thus prevents colonisation, reduces the transmission, and finally lowers the incidence of human campylobacteriosis.