title: Phagocytosis and serum susceptibility of Escherichia coil cultured in iron-deplete and iron-replete media.
abstract: The susceptibility of Escherichia coli cultured in either iron-deplete or iron-replete media to phagocytosis by bovine neutrophils and the bactericidal activity of bovine serum was tested in vitro. Fourteen E. coli isolates from naturally occurring intramammary infections (IMI) were cultured overnight at 37 degrees C in iron-replete media and iron-deplete media. The iron-replete media were trypticase soy broth or a chemically defined medium. The iron-deplete media were either trypticase soy broth plus 0.2 mM alpha, alpha' dipyridyl and 1mM citrate, or the chemically defined medium plus 0.2 mM alpha, alpha' dipyridyl, and 1 mM citrate. Iron-replenished medium was the chemically defined iron-deplete medium plus 40 mM ferric citrate. Bacteria grown in iron-deplete media were less susceptible to phagocytosis compared with bacteria grown in iron-replete media. Replenishing the chemically defined iron-deplete medium with ferric citrate obliterated the decreased susceptibility to phagocytosis observed in iron-deplete media. The iron availability in media used to culture E. coli before assay did not affect the bactericidal action of either the classical pathway of complement or the antibody independent alternative pathway of complement in serum. The growth of bacteria in iron-deplete medium did not alter the expression of capsule compared with growth in iron-replete medium. Iron availability during culture of E. coli altered the susceptibility of isolates to phagocytosis by neutrophils, but had no effect on the susceptibility of isolates to the bactericidal activity of serum.
authors.affiliation: Department of Animal Sciences, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Wise
authors.forename: J S
authors.initials: JS
authors.lastname: Hogan
authors.forename: V B
authors.initials: VB
authors.lastname: Cannon
authors.forename: K L
authors.initials: KL
authors.lastname: Smith
mesh_terms: D000818:Animals; D001770:Blood Bactericidal Activity / Q000276:immunology*; D002417:Cattle / Q000097:blood / Q000276:immunology*; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology / Q000662:veterinary; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D007774:Lactation; D008414:Mastitis, Bovine / Q000276:immunology / Q000382:microbiology; D009504:Neutrophils / Q000276:immunology*; D010587:Phagocytosis
chemical_list: D003470:Culture Media; D007501:Iron