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68 Cards in this Set
- Front
- Back
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features of infections
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features of infections:
- low morbidity and contagiousness, except ringworm - chronic nature: granulomatous response - Ab rarely protect |
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predisposing factors
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predisposing factors:
1. lowered host resistance 2. prolonged antibacterial therapy 3. heavy exposure to fungal spores |
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lab procedures
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lab procedures:
1. wet mount with 10% KOH: dermatophytes in hair/ skin 2. scotch tape mounts in lactophenol cotton blue of fungal hyphae in culture - eg Aspergillus, typical sporing heads -3. histological sections 4. latex agglutination, ELISA for fungal antigens in clinical specimens |
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therapy
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therapy:
1. amphotericin B: toxic 2. ketoconazole (nizoral): systemic use for a variety of fungal infections 3. nystatin: narrow spectrum, candida 4. griseofulvin: PO, ringworm (derm) |
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categories of dz
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categories of dz:
1. dermatomycoses: ringworm (skin) 2. yeasts and yeast-like: Candida, Malassezia (derm, oti) 3. subcutaneous: sporotrichosis 4. systemic: Aspergillus, Blastomycosis, Histoplasmosis, Coccidoicomycosis, Zygomycosis |
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Dermatophytes
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dermatophytes:
- dermatomycosis or "ringworm - zoonotic - skin, hair, nails - immunity associated with DTH - diagnosis: Wood's lamp, wet mount (KOH), culture on Sabouraud medium |
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ringworm lesions
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- circular areas of alopecia
- loss of superficial epithelial layer - crusts -erythema |
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pathogenesis of dermatomycosis
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pathogenesis of dermatomycosis:
1. hyphae in stratum corneum, hair roots 2. keratinases, elastases, proteases 3. hair breaks 4. host inflammatory response: erythema 5. fungus moves to next hair follicle: circular lesions increasing in size - resistance to re-infection associated with development of DTH (delayed type hypersensitivity reaction) |
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ringworm diagnosis
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ringworm diagnosis:
- woods lamp: - fluorescence can be another type besides canis - hair to root - KOH wet mount: arthrospores - sealed container |
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Malassezia pachydermatis signs
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Malassezia pachydermatis (Pityrosporum canis): Yeast
- bottle, peanut or footprint shaped - otitis externa in dogs when too many - chronic dermatitis: pruritis, alopecia, erythema, crusts - lipids help attachment to cell wall components--> pruritis --> skin thickens (elephant-like skin) |
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Malassezia pachydermatis: diagnosis, treatment
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Malassezia pachydermatis (Pityrosporum canis): Yeast
1. diagnosis: gram stain, wet mounts, culture on SAB (fungus) and BA (bacteria) 2. treatment: - topical: Nystatin or clotrimazole - dermatitis: ketaconazole PO (best azole for Malassezia) |
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Dimophic Fungi: Blastomycoses
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Dimophic Fungi: Blastomycoses:
- dogs mainly effected - soil bourne: mycelial phase with spores - occurs in USA - aerosol inhalation --> granulomatous lesions in lungs--> respiratory distress |
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Dimorphic fungi: phases
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Dimorphic fungi:
1. yeast phase: animal body 2. mycelial phase: environment, spores from mycelia may cause infection via respiratory tract |
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Pulmonary blastomycosis
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Pulmonary blastomycosis:
- dimorphic fungi - budding yeast cells: wet mount, cell well stains - hematogenous spread to skin and organs may occur |
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blastomycosis: diagnosis and treatment
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blastomycosis:
1. diagnosis: - wet mount of transtracheal aspirate or skin lesion exudate - culture at 25 C will show mycelial form 2. treatment: itraconazole PO x 60 days |
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dimorphic fungi: histoplasmosis
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dimorphic fungi: Histoplasmosis capsulatum:
- occurs in USA - dogs and cats most effected - infection via inhalation --> granulomatous lesions/ nodules in lung - intestine may be affected - chronic cough, diarrhea, emaciation |
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Histoplasmosis diagnosis
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Histoplasmosis diagnosis:
- histopath - buffy coat smear, Wright stain: also see macrophages - serology - culture: mycelia and typical tuberculate macroconidia |
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Histoplasmosis treatment
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Histoplasmosis treatment: PO
- Itraconazole - Fluconazole |
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Dimorphic bacteria: Coccidioycosis
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Dimorphic bacteria: Coccidioycosis:
- Coccifioides immitis - soil or dust bourne - S USA and S America - dogs most affected: inhaling infective arthrospores - barrel shaped spores - no horizontal transmission from dog to human (Valley fever in ppl) |
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Coccidioycosis: signs
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Coccidioycosis signs:
- dyspnea - weight loss - lymphadenopathy - seizures |
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Coccidioycosis: diagnosis
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Coccidioycosis diagnosis:
- serology - DTH to coccidoidin - skin test - histopath - shouldn't be culture, unless very good containment |
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Coccidioycosis: histopath
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Coccidioycosis: histopath:
1. lungs: acute inflammation, mature "spherule" with endospores surrounded by eosinophilic layer 2. lymph nodes: wet mouth of pus may show spherules |
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Coccidioycosis: treatment and control
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Coccidioycosis: treatment and control:
1. tx: ketaconazole or itraconazole for up to 12 months 2. control: reduce exposure to dust in endemic areas - suspect cases should be serologically tested |
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Fungi gen
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fungi:
- filamentous, branching (moulds) or unicellular (yeasts) - aerobic - Sabourad agar: pH 5.5 - 1-4 weeks 35 C (room T) - culture and microscopic morphology important in dx |
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filamentous fungi
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filamentous fungi:
- gross and microscopic appearance: mycelium - Aspegillus |
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unicellular fungu
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unicellular fungi:
- yeasts - Malasezzia: peanut shaped, dog's ear |
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common fungal pathogens
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common fungal pathogens:
1. Aspergillus fumigatus: septa 2. Mycosporum canis 3. Candida albicans: bowling pin shaped 4, Malasezzia pachydermatis 5. ringworm |
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Mycelium
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mycelium:
- mass of hyphae (filaments) |
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dimorphic fungi gen
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dimorphic fungi:
1. yeast form: 37 C 2. mycelial form 25 C - survival mechanism |
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conidia
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conidia:
spores |
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arthroconidia/ arthrospores
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arthroconidia/ arthrospores:
- spores from hyphal fragmentation - ringworm fungi |
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geophilic vs zoophilic
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1. geophilic: natural habitat is soil, cannot use cleanup to contro;
2. zoophilic: animals are the source |
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important dematophytes
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important dematophytes:
1. M. canis 2. M. gypseum 3. M. nanum 4. T. verrucosum 5. T. equinum 6. T. mentagrophytes 7. M. gallinae |
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microsporum canis
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Microsporum canis:
- zoophilic - cats and dogs - spindle-shaped macroconidia - lactophenol cotton blue wet mount for culture |
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Microsporum gypseum
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Microsporum gypseum:
- geophilic - Rodents, dogs, horses - boat-shaped macroconidia |
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Microsporum nanum
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Microsporum nanum:
- geophilic - pigs |
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Trichophyton verrucosum
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Trichophyton verrucosum:
- zoophilic - cattle |
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Trichophyton equinum
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Trichophyton equinum:
- zoophilic - horses |
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Trichophyton mentagrophytes
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Trichophyton mentagrophytes:
- zoophilic - horses, carnivores (bats, mice...) - cigar-shaped macroconidium and numerous microconidia |
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M gallinae
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M gallinae:
- zoophilic - very rare cases in fowl |
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Control of dermatophytes
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dermatophytes:
contaminated areas: - Na hypochlorite - formalin - enilconazole |
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tx dermatophytosis
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dermatophytosis:
1. topical: lime sulphur, imidazole (keto) creams, shampoos 2. systemic: griseofulvicin, itraconazole, ketoconazole (broad spectrum) 3. vaccine: live attenuated for cats, cattle |
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griseofulvicin
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griseofulvicin:
- tx dermatophytosis - carnivores, cattle |
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aspergillosis different spp
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aspergillosis:
1. dogs: nasal, destruction of turbinate bones, profuse blood-tinged exudate 2. chicks: brooder pneumonia 3. cattle: mycotic abortion from placental invasion 4. horses: gutteral pouch mycosis (can rupture int. carotid), keratomycosis (keratitis) |
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aspergillosis gen
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aspergillosis:
- common: A. fumigatus - fruiting heads - produce elastases, proteases and dermonecrotoxin which destroys tissue |
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aspergillosis dx
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aspergillosis dx:
1. KOH wet mounts of deep scrapings, tissue: septate hyphae 2. lung sample: conidial heads 3. rads, rhinoscopy 4. culture on Sab, wet mount of colony surface: typical conidial heads 5. serological test (AGID): dogs |
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aspergillosis control
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aspergillosis control:
- poultry: litter change - cattle: avoid bad hay, silage |
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aspergillosis tx
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aspergillosis tx:
1. horses: keto locally and itra systemic 2. keratitis: natamycin or miconazole topical 3. nasal: clotrimazole infusion preferred, or fluconazole systemic |
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yeasts and dz
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yeasts and dz:
- round/ oval - hyphae can occur in tissues - skin, mucous mem - second to immunosupression, antibacterial therapy - candida, cryptococcus (not commensal) , malassezia |
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Candidiasis
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Candidiasis/ moniliasis/ thrush:
- albicans commensal of GI, infections endogenous - yeast and filamentous (tissue) |
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Candidiasis spp
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Candidiasis: often white plaques
1. dogs: mycotic stomatitis, genital 2. young animals: prolong antibiotics, enteritis 3. poultry: crop mycosis (thrush) 4. horses: metritis, vaginitis |
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Candidiasis pathogenesis
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Candidiasis pathogenesis:
1. adheres to mucous mem 2. pseudohyphae invade epithelium 3. pseudomembranous ulcerative inflammation |
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Candidiasis dx
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Candidiasis dx:
- KOH wet mount or G stain: budding yeasts - culture - latex agglutination Ag kits for body fluids |
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Candidiasis tx
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Candidiasis tx:
1. Nystatin topical 2. ketoconazole 3. nystatin oral: narrow spectrum (yeasts), for GI overgrowth |
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Cryptococcus gen
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Cryptococcus gen:
- habitat: soil, pigeon droppings - remains yeast form in environment and host - enzymes, including phospholipases cause granulomas |
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Cryptococcus dz progression
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Cryptococcus dz progression:
- sporadic in cats and dogs 1. airbourne 2. nasal granulomas 3. paranasal sinuses 4. hematogenous dissemination: eg brain, eyes 5. sneezing, sniffling, mucopurulent/ hemorrhagic discharge |
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Cryptococcus diagnosis
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Cryptococcus dz progression:
- wet mounts: antiphagocytic capsule - culture - agglutination |
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Cryptococcus tx/ control
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Cryptococcus tx/ control:
1. itraconazole 2. fluconazole 3. decontaminate affected premises |
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Sporotrichosis
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Sporothrix schenckii
- soil-bourne worldwide - dimorphic - horses, mules, rarely carnivores - infection via skin wounds--> lymphatic spread |
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sprotrichosis tx
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sprotrichosis tx:
1. horses: K or Na iodide 2. cats: itraconazole |
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Zygomycosis
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Zygomycosis:
- rhizopus, mucor, absidia, mortierella - saprophytes - dz after inhalation or ingestion - mycotic abortion - tissue: aseptate hyphae - amphotericin B: poor prognosis |
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Mycotoxicoses
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Mycotoxicoses:
- mould growing on feed - acute or chronic poisoning, immunosupression. carcinogenicity, teratogenicity - non-contagious, sporadic - dx: demonstration of toxin, may be indicated by refusal of feed |
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Aflatoxicosis gen
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Aflatoxicosis (a mycotoxicosis):
- Aspergillus ( & Penicillum, Rhizopus, Mucor) - mainly cattle, poultry - acute: bloody diarrhea, death - subacute: icterus, abortion - chronic: decreased feed efficiency, rough coat |
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Aflatoxicosis dx and tx
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Aflatoxicosis:
1. dx: PM tissues, feed sample (HPLC, ELISA), chick embryo bioassay 2. control: test feed, ammoniate feed, addition of toxin binders |
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Ochratoxicosis
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Ochratoxicosis (a mycotoxicosis):
- Aspergillus, Penicillum - pigs, poultry, horses - weight loss, kidney and liver damage - demonstration of toxin in feed, removal |
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Ergotism
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Ergotism (a mycotoxicoses):
- Claviceps purpurea growth (ergots) in seedheads - cattle, sheep, horses, pigs, poultry - neurotoxicity, convulsions, gangrene of extremities - ergots removed: mechanically or flotation |
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Facial eczema
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facial eczema (mycotoxicoses):
- Australia, SA, US 1. Pithomyces chartarum 2. spoidesmin 3. liver damage 4. buildup of phylloerithrin 5. photodynamic activity 6. necrosis, sloughing of skin, moist dermatitis, hyperemia |
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facial eczema dx/tx
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facial eczema dx/tx:
1. dx: jaundice, history, sporidesmin detection in blood by ELISA 2. control: fungicide spray on pastures, zinc salts in feed to reduce liver toxicity |
