title: Pleiotropic effects of polysaccharide capsule loss on selected biological properties of Streptococcus suis.
abstract: In this study, an unencapsulated Streptococcus suis mutant was used to investigate the pleiotropic effects resulting from capsule loss. The capsule deficient mutant of S. suis acquired a biofilm-positive phenotype, which was associated with significantly increased cell surface hydrophobicity. Cell-associated fibrinogen-binding and chymotrypsin-like activities were decreased in the unencapsulated mutant. The mutant did not differ significantly from the encapsulated parent strain for minimal inhibitory concentrations to penicillin G, ampicillin, and tetracycline. However, while the encapsulated strain was highly resistant to the bactericidal action of penicillin G and ampicillin, the unencapsulated mutant was approximately 60-fold more sensitive. Compared with the parent strain, the unencapsulated mutant induced a much higher inflammatory response in monocyte-derived macrophages resulting in an increased secretion of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-8. The capsule appears to hinder important adhesins or hydrophobic molecules that mediate biofilm formation, as well as cell wall components capable of stimulating immune cells.
authors.affiliation: Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Tanabe
authors.forename: Laetitia
authors.initials: L
authors.lastname: Bonifait
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
authors.forename: Louis
authors.initials: L
authors.lastname: Grignon
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
authors.forename: Daniel
authors.initials: D
authors.lastname: Grenier
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016667:Bacterial Capsules / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D002918:Chymotrypsin / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D005340:Fibrinogen / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007378:Interleukins / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008855:Microscopy, Electron, Scanning; D017011:Streptococcus suis / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D013752:Tetracycline / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000378:metabolism; D020298:U937 Cells
chemical_list: D000900:Anti-Bacterial Agents; D007378:Interleukins; D014409:Tumor Necrosis Factor-alpha; D000667:Ampicillin; D005340:Fibrinogen; D002918:Chymotrypsin; D013752:Tetracycline