title: Decreased neutrophil bactericidal activity during phagocytosis of a slime-producing Staphylococcus aureus strain.
abstract: Phagocytosis and intracellular killing by bovine polymorphonuclear leukocytes (PMN) are important host defence mechanisms against mastitis caused by Staphlylococcus aureus. We compared the phagocytosis and overall killing of a non slime-producing (NSP) S. aureus and its slime-producing (SP) variant by blood PMN, using an in vitro bacteriological assay. Seven clinically healthy Holstein-Friesian dairy cows in mid-lactation stage were used for this purpose. The percentages of overall killing for the NSP and SP variant were 34+/-3% and 21+/-4% (P < 0.05) and the corresponding percentages of phagocytosis were 40+/-4% and 31+/-4%, respectively. A significant positive correlation (r = 0.79; P < 0.001) was found between phagocytosis and overall killing. These results suggest that the presence of slime was responsible for a decreased phagocytic ingestion and overall killing.
authors.affiliation: Ghent University, Faculty of Veterinary Medicine, Department of Physiology, Biochemistry and Biometrics, Merelbeke, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Barrio
authors.forename: F
authors.initials: F
authors.lastname: Vangroenweghe
authors.forename: H
authors.initials: H
authors.lastname: Dosogne
authors.forename: C
authors.initials: C
authors.lastname: Burvenich
mesh_terms: D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial / Q000662:veterinary; D005260:Female; D066298:In Vitro Techniques; D008414:Mastitis, Bovine / Q000276:immunology* / Q000382:microbiology; D009504:Neutrophils / Q000276:immunology*; D010587:Phagocytosis / Q000502:physiology*; D013203:Staphylococcal Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000145:classification / Q000276:immunology* / Q000502:physiology