Zygomycosis

Mucor liver Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

• Also known as mucormycosis, hyphomycosis and phycomycosis

• Caused by strains of Mucor, Absidia, Rhizopus and Mortierella
  • Mucor circinelloides(rare), Rhizomucor pusillus and R. meihi
  • Absidia corymbifera often causes zygomycosis in cattle and pigs
  • Rhizopus arrhizus, R. microsporus and R. rhizopodormis
  • Mortierella wolfi implicated in bovine abortion (mycotic placentitis), M. hygrophila in fowl and M.polycephala in cattle

• Occurs widely in nature

• Infection is by inhalation and ingestion

• Infects lymph nodes of the respiratory and alimentary tract
  • Lymph nodes enlarge and become caseous
  • Can cause stomach and intestinal ulcers

• Granulomatous lesions which can ulcerate

Mucor mould on the ruminal surface Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath</sup?

• Mostly localised lesions but can be generalised
• Pigs
  • Mediastinal and submandibular lymph nodes lesions
  • Embolic tumours in the liver and lungs
  • Can also be present in gastric ulcers

• Cattle
  • Bronchial, mesenteric and mediastinal lymph nodes lesions
  • Ulcers of the nasal cavity and abomasum also occur
  • Often contaminate the placenta

• Horses, dogs, cats, sheep, mink, guinea-pigs and mice can also be infected

• Microscopically:
  • Fragments of non-septate hyphae which are branched and coarse
  • Rhizomucor produce a thick, grey mycelium and have short, black, spherical sporangia
  • Mucor produce thick, colourless mycelium with no rhizoids. Globose spoangia with small spores are present and sporagiospores are simple or branched.
  • Absidia resemble Rhizopus grossly
  • Mortierella produce white, velvet colonies on Sabouraud's Dextrose and Blood agar

• Grows on Sabauraud's Dextrose agar
  • Common contaminants

• Treatment is with Amphotericin B
  • Surgery is also an option in treatment

Saprolegnia salmon Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Saprolegnia Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath Sporangiospores Copyright Professor Andrew N. Rycroft, BSc, PHD, C. Biol.F.I.Biol., FRCPath

• Also called phycomycosis, mucormycosis
• In horses due to Basidiobolus haptosporus
• Pythiosis in horses and dogs is similar (caused by Pythium sp.
• In warm, humid environments
• Grossly:
  • Lesions on head, limbs, ventral body
  • In dogs also dorsolumbar region
  • Yellow, rough, necrotic tissue
• Micospocically:
  • Hyphae ingranulomatou tissue
  • Many eosinophils

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Zygomycosis