title: Bovine-associated CNS species resist phagocytosis differently.
abstract: BACKGROUND
  Coagulase-negative staphylococci (CNS) cause usually subclinical or mild clinical bovine mastitis, which often remains persistent. Symptoms are usually mild, mostly only comprising slight changes in the appearance of milk and possibly slight swelling. However, clinical mastitis with severe signs has also been reported. The reasons for the differences in clinical expression are largely unknown. Macrophages play an important role in the innate immunity of the udder. This study examined phagocytosis and killing by mouse macrophage cells of three CNS species: Staphylococcus chromogenes (15 isolates), Staphylococcus agnetis (6 isolates) and Staphylococcus simulans (15 isolates). Staphylococcus aureus (7 isolates) was also included as a control.
  
  
  RESULTS
  All the studied CNS species were phagocytosed by macrophages, but S. simulans resisted phagocytosis more effectively than the other CNS species. Only S. chromogenes was substantially killed by macrophages. Significant variations between isolates were seen in both phagocytosis and killing by macrophages and were more common in the killing assays. Significant differences between single CNS species and S. aureus were observed in both assays.
  
  
  CONCLUSIONS
  This study demonstrated that differences in the phagocytosis and killing of mastitis-causing staphylococci by macrophages exist at both the species and isolate level.
authors.forename: Silja
authors.initials: S
authors.lastname: Avall-Jääskeläinen
authors.forename: Joanna
authors.initials: J
authors.lastname: Koort
authors.forename: Heli
authors.initials: H
authors.lastname: Simojoki
authors.affiliation: Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, P,O, Box 57, FIN-00014, Helsinki, Finland. suvi.taponen@helsinki.fi.
authors.forename: Suvi
authors.initials: S
authors.lastname: Taponen
mesh_terms: D000818:Animals; D002417:Cattle; D061252:Feeder Cells; D005260:Female; D008264:Macrophages / Q000502:physiology*; D008414:Mastitis, Bovine / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C / Q000276:immunology; D010587:Phagocytosis; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013210:Staphylococcus / Q000276:immunology*