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*Mycology-2011: General Features

*kingdom FUNgi (~ 400 pathogenic species)

* Eukaryotic, nonphotosynthetic,

* filamentous or unicellular

*Rarely Epidemic (ie. Contagious)

* Exception (Dermatophytes) - zoonotic

* Endemic – Yeast, Dimorphic fungi – saprozoonotic

* Predisposing factors

* environment load, immune status, prolonged Abx

*Asexual reproduction

*spore structures impt. Dx tools

*Unique Cell Envelopes : Ergosterol

* 80-90% CHO (chitin, mannan, -glucans)

* Aerial/Vegetative hyphae – filaments (mold phase)

* Aseptate hyphae – Rhizopus or Mucor spp.

* Pseudohyphae - Candida albicans (yeast)

* Septate hyphae – most ie. Aspergillus spp.

* Conidia – spores (used interchangeably)

* See next slide for overview

* Dimorphic – mold-like and yeast-like phases

*Mycoses (us) and mycotoxicoses

* ‘Philics – Anthropo-, Geo-, Zoo-

* Rhizoid – root like structure (Rhzopus spp.)

* Sporangium – closed sac-like structure (sporangiospores)

* Yeast: Unicellular (budding)

Rhizopus

* Some Terminology

C. albicans

Malassezia

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Dermatophyte macroconidia

Endospores

*Asexual Spore Structures

*Arthroconidia

*Dermatophytes, Coccidioides

*Blastoconida

* Budding (yeast), hyphae

*Chlamydoconidia

*Histoplasma sp., Candida

*Endospores

*Coccidioides (spherule)

*Macro- and Microconidia

*Dermatophytes

*Phialoconidia

*Aspergillus spp.

*Sporangiospores

*aseptate fungi Rhizopus, Mucor

Histoplasma

Tuberculate

chlamydoconidia

Aspergillus

Sporangiospores

arthroconidia

*General Diagnostic Lab Procedures

*Sabourauds Media (culture temp. 22 - 25 oC)

*pH 5.6 inhibits bacteria

*Abx (Chloramphenicol), +/- Cycloheximide

*BA (Brain Heart Infusion Agar or Phytone Yeast Extract)

*Scotch Tape Mount - Lactophenol Cotton Blue (LPCB)

*10 - 20% KOH wet mount, India-ink (Cryptococcus)

*Histological Stains:

*PAS (Periodic Acid Schiff) – stain red

*Methenamine Silver – stain brown or black

*H+Eosin (Histoplasma)

*Pan-fungal PCR (18s – 28 s rDNA) + sequencing

*MALDI-TOF mass spec

India ink

PAS

Methenamine silver

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*Antifungals – Ergosterol Inhibitors

*Polyenes (Fungicidal/static) – binds ergosterol

*Nystatin - mucocutaneous candidiasis (C. albicans)

*Amphotericin B - yeast, dimorphics (nephro/cardiotoxicity)

* dogs/cats, horses – i.v. only

* Imidazoles and Triazoles (Fungistatic/cidal) Topical/p.o.

* Block ergosterol synthesis

* IMIDAZOLES - Ketoconazole (KTZ), Miconazole (MCZ), Clotrimazole (CTZ)

*TRIAZOLES - wider spectrum of activity, fewer side effects

* Enilconazole (ECZ ) – label use in dogs and horses (topical)

* Itraconazole (ITZ) – label use cats, Fluconazole (FCZ)

* Voriconazole (VCZ) – ELDU, $$ but (aspergillosis in companion birds).

*Antifungals

*Allylamine Antifungals - block ergosterol synthesis

* Terbinafine (dogs/cats) – oral (dermatophytes)

* Flucytosine (5-fluorocytosine) typically with AMB or FCZ

* antineoplastic agent (not at antifungal doses)

* Indirectly inhibits DNA, protein synthesis (mRNA alteration)

* Yeasts, Sporothrix schenckii in dogs/cats

* Griseofulvin (Penicillium griseofulvin) – oral (dogs/cats/horses, cattle)

* Inhibits microtubule assembly (mitosis compromised)

* Systemic for Dermatophytes ; Accumulates in keratin, teratogenic

* Iodides (Na or K)

* Txt for Sporothrix schenckii in horses

*Echinocandins - block glucan synthesis – “penicillin of Antifungals”

* Caspofungin (Merck) – ELDU parenteral for Candidemia, invasive aspergillosis (dog/cat)

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Fungal Cell Envelope and Antifungals

Erg Erg

1,3-β glucan synthase

1,6-β glucan

Chitin

Echinocandins (Capsofungin)

‘Azoles (ITZ)

Allylamine (Terbinafine)

1,3-β glucan

Lanosterol

Polyenes (AMB)

Squalene

Mannoproteins

= Ergosterol

I. Opportunistic Mycoses:

- Candidiasis, Aspergillosis, Zygomycosis

II. Cutaneous and Subcutaneous Mycoses:

- Dermatophytes, Malassezia, Sporothrix

III. Systemic Mycoses:

- Cryptococcosis, Histoplasmosis, Blastomycosis and Coccidioidomycosis

IV. Fungal –like pathogens: an Algae, Mycotic Swamp Cancer …

*The Fungal Pathogens

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*Opportunistic Mycoses: Candida albicans

*Candidiasis : Predisposing factors: Prolonged Abx, immunodeficiency

*Mycotic Stomatitis - (Dogs and cats)

*whitish-grey oral plaques (pseudomembranous and ulcerative)

*Crop Mycosis (Sour Crop or Thrush)

*Risk factor Abx in feed

* young poultry, companion birds

* can be significant economically

* pseudomembranous plaques - oral cavity, oesophagus, crop

*Txt Nystatin/VitA in feed, CuSO4 (water)

*Mastitis in dairy cattle

*C. albicans, krusei – unhygenic practices

*Candida spp.: Dx/Txt

*Direct examination impt. material

*KOH wet mount or Gram stain

*Pseudohyphae, yeast (3-10 m)

*BA (Yes but no)

*CHROMagar Candida (BBL ™)

* selective + chromogenic differentiation

*Germ tube (pseudohyphae) test easy

*Commercial ID available (API –Yeast)

*PCR, MALDI-TOF ms

*Nystatin (topical): oral mucosal I.U.(metritis),

*Miconazole cream, topical AMB

*Systemic infections – rare (ITZ)

C. albicans C. krusei

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*Aspergillosis

*A. fumigatus : Inhalation/ingestion of spores (poor hay/silage)

*Brooder pneumonia in chicks (contaminated litter)

*Guttural Pouch Mycosis , pneumonia and keratomycosis in horses

*Unilateral, internal carotid erosion,

*Epistaxis, mucopurulent nasal discharge, dysphagia/laryngeal paralysis, head position

*Nasal Aspergillosis in Dogs

* serosanguinous nasal discharge, epistaxis

*ulceration external nares

* turbinate destruction,

*Trivia: German shepherds A. terreus

*Abortion in cattle, horses – following Aspergillemia

*Pneumonia (high mortality), UTI, enteritis (foals/calves)

*Aspergillus: Dx/Txt

*Direct smear (KOH) - deep scrapings/tissue (stringency)

* Septate, dichotomous branching

* conidial heads only when O2 available

* ie. lungs, nasal sinus, culture plates

*Dogs/Horses – radiology (neoplasia) and/or rhinoscopy

*SAB, Colony characteristics, LPCB

* Intervention

* Sx for Canine/Equine Infections (nasal, guttural pouch)

* ITZ (p.o.), ECZ instilled nasally (dogs and horses)

*Voriconazole – companion birds

*Management (poultry, ruminants, horses)

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*Phylum Zygomycota: Zygomycoses

*Aseptate fungi - Rhizopus, Mucor and Mortierella

* Inhalation/ingestion/cutaneous puncture

* localized granulomatous lesions – systemic

*Angiotrophic – hematogenous dissemination

*Cattle

*Abortion, pneumonia, Less commonly enteritis, rumenitis, lymphadenitis

(mediastinal/mesenteric)

*Mycotic Abortion (Mortierella wolfii – cattle) – 1st Canadian case (CVJ,

51:2010) – unusual abortion – brain – pneumoniae and kidney

*Swine - mediastinal lymphadenitis, enteritis (piglets), gastric ulcers

*Rarely:

*Dogs - enteritis

*Cats – necrotizing pneumonia, enteritis

*Horses, sheep, mink, guinea pigs, mice

*Zygomycetes: Dx/Txt

*Direct examination – aseptate, wide

(5-15 m) hyphae

*Lesion, histological/microscopic

characteristics

*Culture (SAB) easy for most –

establishing cause impt.

*Colony morphology, LPCB

*aseptate, sporangia

*Rhizoids

*Nodal – Rhizopus

*Anodal - Mucor

*Txt – feed quality

Methenamine silver

+ light green counterstain

Mucor