title: Lactobacillus rhamnosus GG inhibits the toxic effects of Staphylococcus aureus on epidermal keratinocytes.
abstract: Few studies have evaluated the potential benefits of the topical application of probiotic bacteria or material derived from them. We have investigated whether a probiotic bacterium, Lactobacillus rhamnosus GG, can inhibit Staphylococcus aureus infection of human primary keratinocytes in culture. When primary human keratinocytes were exposed to S. aureus, only 25% of the keratinocytes remained viable following 24 h of incubation. However, in the presence of 10(8) CFU/ml of live L. rhamnosus GG, the viability of the infected keratinocytes increased to 57% (P = 0.01). L. rhamnosus GG lysates and spent culture fluid also provided significant protection to keratinocytes, with 65% (P = 0.006) and 57% (P = 0.01) of cells, respectively, being viable following 24 h of incubation. Keratinocyte survival was significantly enhanced regardless of whether the probiotic was applied in the viable form or as cell lysates 2 h before or simultaneously with (P = 0.005) or 12 h after (P = 0.01) S. aureus infection. However, spent culture fluid was protective only if added before or simultaneously with S. aureus. With respect to mechanism, both L. rhamnosus GG lysate and spent culture fluid apparently inhibited adherence of S. aureus to keratinocytes by competitive exclusion, but only viable bacteria or the lysate could displace S. aureus (P = 0.04 and 0.01, respectively). Furthermore, growth of S. aureus was inhibited by either live bacteria or lysate but not spent culture fluid. Together, these data suggest at least two separate activities involved in the protective effects of L. rhamnosus GG against S. aureus, growth inhibition and reduction of bacterial adhesion.
authors.affiliation: Institute of Inflammation and Repair, the University of Manchester, Manchester, United Kingdom.
authors.forename: Walaa
authors.initials: W
authors.lastname: Mohammedsaeed
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, the University of Manchester, Manchester, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: McBain
authors.affiliation: Faculty of Life Sciences, the University of Manchester, Manchester, United Kingdom.
authors.forename: Sheena M
authors.initials: SM
authors.lastname: Cruickshank
authors.affiliation: Institute of Inflammation and Repair, the University of Manchester, Manchester, United Kingdom catherine.oneill@manchester.ac.uk.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: O'Neill
mesh_terms: D000898:Antibiosis; D001422:Bacterial Adhesion; D002470:Cell Survival; D002478:Cells, Cultured; D006801:Humans; D015603:Keratinocytes / Q000382:microbiology* / Q000502:physiology*; D052201:Lacticaseibacillus rhamnosus / Q000502:physiology*; D013211:Staphylococcus aureus / Q000254:growth & development / Q000502:physiology*