MYCOLOGY

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MYCOLOGY
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FUNGI

• Uni or multicellular organisms
• Eukaryotes
• Defined nuclei
• Cell walls of carbohydrate and chitin
• Saprophytic or parasitic
• Vegetative and sexual reproduction

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SAPROPHYTIC FUNGI, CHANTERELLES
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FUNGI IN VETERINARY MEDICINE

• Dermatophytes grow on skin and hair
• Yeasts grow on mucous surfaces and in the body
• Systemic infection hyphae and yeasts

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FUNGI IN VETERINARY MEDICINE

• Fungal products
• Beneficial (antibiotics)
• Harmful (mycotoxins)
• Fungal spoilage animal foods, forages, animal
  products such as meat and hides

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Terminology

• Ascospore asexual spore produced in a sac-like
  structure called an ascus
• Arthospores asexual spore formed by the
  disarticulation of the mycelium
• Chlamydospores thick-walled, resistant spores
  formed by the direct differentiation of hyphae
• Conidia asexual spore formed from hyphae by
  budding or septal division
• Conidiophore a stalk-like branch from the
  mycelium in which conidia develop either singly
  or in numbers

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Terminology

• Germ tubes tube-like structures produced by
  germinating spores
• Hyphae the filaments that composed the body of a
  fungus
• Macroconidia large multinucleate spores
• Microconidia single-celled spores
• Mycelium a mat made up of interwining
  thread-like hyphae
• Pseudohyphae filaments composed of elongated
  budding cells that have failed to detach

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FUNGAL SPOILAGE, SILAGE
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MUCOR

• Hyphae 5-15?m
• Grow fast in culture
• Greyish white aerial mycelium
• Mycotic abortion
• Rumen ulcers
• Systemic mycosis in young or debilitated animals
• Meat spoilage

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MUCOR IN CULTURE
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MUCOR ON MEAT. NOTE SPORANGIA
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YEASTS

• Single cells
• Reproduce vegetatively by budding
• Occasionally form pseudomycelium
• Sexual reproduction by forming ascospores within
  cell
• Candida, Malassezia, Cryptococcus, Histoplasma

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CANDIDA

• 3-6 m?, oval cells
• Gram positive
• Pseudohyphae
• Germ tubes
• Chlamydospores
• Grows at 37?C on Sabourauds dextrose agar
• Creamy white 2mm colonies

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CANDIDA COLONIES
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PSEUDOHYPHAE, CANDIDA
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CANDIDA ALBICANS IN ANIMAL DISEASE

• Cattle
• Mycotic abortion
• Rumenal infections
• Mastitis
• Dogs-chronic enteritis and vaginitis/vulvitis
• Birds-crop infections, enteritis

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CRYPTOCOCCUS

• C. neoformans
• Nasal cavity of cats with chronic rhinitis
• Encapsulated
• 20 ?m total

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CRYPTOCOCCUS IN INDIAN INK TO SHOW CAPSULE
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DERMATOPHYTES

• Septate branching hyphae
• Digest keratin
• Microconidia, arthrospores, macroconidia
• Grow on Sabourauds within 7-14 days at 28?C
• Identify by surface appearance and colour of
  underside
• Confirm by shape of macroconidia

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MICROCONIDIA
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MACROCONIDIA
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MICROSPORUM

• Ringworm in man and animals
• Microconidia en thyrse (along sides of hyphae)
• May fluoresce under Woods light

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M. CANIS

• Ringworm in cats and dogs transmissible to man
• Grows on hair with arthrospores ectothrix
• Microconidia relatively common
• Macroconidia elliptical with up to 14 divisions,
  rare on isolation
• Fluoresces
• Colonies smooth surface, yellow underside

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M. CANIS
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M. CANIS ON MAN
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TRICHOPHYTON

• Ringworm in man and animals
• Club-shaped macroconidia
• Spiral hyphae
• No fluorescence

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SPECIES OF TRICHOPHYTON

• T. verrucosum
• Ringworm in cattle transmissible to man
• Abundant chlamydospores
• Large spore ectothrix on hair
• Colonies slow growing
• Deep in agar
• T. equinum horse
• T. gallinae fowl

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T. VERRUCOSUM, CALF
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ASPERGILLUS

• Septate branching hyphae
• Sporing heads or conidia in oxygen
• Conidiophore
• Aspergillus may have sexual stages
• Use colonial appearance, size and details of
  conidiophore to identify

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ASPERGILLUS FUMIGATUS

• On food
• On fodder
• Spores infect young non-immune or
  immunosuppressed animals
• Grows best on Sabourauds at 24-28?C
• Star shaped colonies
• Green-blue with sporing heads

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ASPERGILLUS FUMIGATUS
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ASPERGILLUS CONIDIOPHORE
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ASPERGILLUS IN AIRSACS
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BOVINE LUNG, ASPERGILLOSIS
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MYCOTOXINS

• Aspergillus flavus produces aflatoxin
• Aflatoxin is carcinogenic
• Claviceps purpurea (ergot) produces alkaloids
• Fusarium culmorum produces zearelenone toxin
• Penicillium rubrum produces rubratoxin
• Penicillium viridicatum produces Ochratoxin A