title: Leukotoxic factors produced by staphylococci of ovine origin.
abstract: Leukotoxins produced by staphylococci, especially Staphylococcus aureus, have long been considered important virulence determinants. The present assay examined 26 strains of staphylococci isolated from sheep for their ability to produce factors leukotoxic to polymorphonuclear leukocytes deriving from ovine mammary glands. Twenty one strains were coagulase-negative staphylococci and five coagulase-positive. Of the coagulase-negative staphylococci 17 were isolated from subclinical mastitis and four from the teat skin. The coagulase-positive strains were isolated from clinical mastitis and caused death to 91-100% of the cells. The coagulase-negative strains isolated from subclinical mastitis caused death to less than 50% of cells, while those from the skin did not affect any cells. The concentration of active leukotoxins is an important staphylococcal virulence factor. Low production of leukotoxins or no production by coagulase-negative staphylococci may determine their ability to survive the mammary gland defenses or cause clinical mastitis.
authors.affiliation: Department of Farm Animal and Equine Medicine and Surgery, Royal Veterinary College, Herts, England.
authors.forename: A R
authors.initials: AR
authors.lastname: Burriel
authors.forename: G J
authors.initials: GJ
authors.lastname: Dagnall
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D005098:Exotoxins / Q000096:biosynthesis / Q000633:toxicity*; D005260:Female; D009504:Neutrophils / Q000187:drug effects; D012756:Sheep / Q000382:microbiology*; D013210:Staphylococcus / Q000472:pathogenicity*
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; C018579:leukotoxin