Sporotrichosis in a horse -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
Sporotrichosis cigar shaped cells -Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath
  • Sporothrix schenckii
  • Occurs in soil, wood and vegetation
    • Saprophyte of both decaying and healthy vegetation
  • Worldwide
  • Exogenous infections through wounds
  • Sporadic infections
  • Non-contageous
  • Causes subcutaneous nodules or granulomas
    • Nodules ulcerate discharging pus
  • The bones and viscera can be involved which terminates in mortality
    • This is rare
    • Reported in dogs and horses
  • Affects dogs, horses, cats, monkeys, mules, camels, donkeys, cattle, fowl and rodents
    • Most commonly seen in horses as an ascending lymphocutaneous infection of the legs
    • Can be confused with epizootic lymphangitis in horses
  • Single cell, cigar shaped
    • Usually found within neutrophils
    • Yeast cell clusters with peripheral eosinophilic rays can be seen in tissue sections
  • Stained using PAS, Gram stain (positive), fluorescent antibody and Calcofluor White
  • Latex agglutination and immunodiffusion serology can be performed
  • Grows on Blood agar and Sabouraud's Dextrose agar in one to three weeks
    • At 37°C:
      • Colonies are smooth, cream to tan coloured and soft
      • No mycelium can be seen
    • At 25°C to 27°C:
      • Colonies turn from white and soft to tan to brown to black
      • Leathery, wrinkled and coarse
      • Mycelium can be seen as branching septate hyphae
      • Conidiospores can also be seen