title: Encapsulation of Staphylococcus aureus isolates from mastitic milk: relationship between capsular polysaccharide types 5 and 8 and colony morphology in serum-soft agar, clumping factor, teichoic acid, and protein A.
abstract: A total of 193 Staphylococcus aureus isolates from bovine, caprine, and ovine mastitis producing type 5 or 8 capsular polysaccharides were investigated for colony morphology in serum-soft agar and agglutinability by an anti-teichoic acid serum, after cultivation in modified staphylococcus medium no. 110. Also, 40 of these strains were cultivated in brain heart infusion and submitted to clumping factor and protein A detection tests. Considering capsular serotyping as a reference method, diffuse growth in serum-soft agar and inagglutinability by anti-teichoic acid serum identified, respectively, 57.5 and 45% of encapsulated strains cultivated in brain heart infusion and 85.5 and 77.2% of those cultivated in modified staphylococcus medium 110. Consequently, these indirect techniques underestimated encapsulation and were greatly influenced by culture conditions. Whatever the medium used, diffuse colony morphology in serum-soft agar was generally characterized by a masking of teichoic acid and protein A. By contrast, these surface antigens were detected in association with compact morphology; the presence of a thin or discontinuous capsular material could explain this result. Moreover, the masking of teichoic acid and the removal of capsular polysaccharide by washing in saline suggest that type 8 capsular polysaccharide is more abundant and labile than type 5.
authors.affiliation: Institut National de la Recherche Agronomique, Nouzilly, France.
authors.forename: L
authors.initials: L
authors.lastname: Sutra
authors.forename: C
authors.initials: C
authors.lastname: Mendolia
authors.forename: P
authors.initials: P
authors.lastname: Rainard
authors.forename: B
authors.initials: B
authors.lastname: Poutrel
mesh_terms: D000371:Agglutination; D000818:Animals; D002417:Cattle; D003470:Culture Media; D005260:Female; D015511:Goat Diseases / Q000382:microbiology; D006041:Goats; D007106:Immune Sera / Q000276:immunology; D008413:Mastitis / Q000382:microbiology / Q000662:veterinary*; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D011135:Polysaccharides, Bacterial / Q000032:analysis; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013205:Staphylococcal Protein A / Q000032:analysis; D013211:Staphylococcus aureus / Q000254:growth & development*; D013682:Teichoic Acids / Q000276:immunology
chemical_list: D003470:Culture Media; D007106:Immune Sera; D011135:Polysaccharides, Bacterial; D013205:Staphylococcal Protein A; D013682:Teichoic Acids