Mycology Part 1B Flashcards
What is Eumycotic Mycetoma?
- Tumorous, granulomatous infections of the skin and subcutaneous tissues caused by true fungi
- May rarely invade bone
- History:
- First reported in man in Madurai, India
- Maduramycotic mycetoma
- Chromoblastomycosis
- First reported in man in Madurai, India
What is the clinical manifestation of Eumycotic Mycetoma?
- Tumorous granulomas
- Skin and subcutaneous tissues, rarely bone
- Abscesses with draining tracts
- Granules - Usually colored
What Fungi are responsible for Eumycotic Mycetoma in animals?
- Pseudallescheria boydii
- Curvularia geniculata
- Helminthosporium spp.
- Madurell mycetomatis
- Cochliobolus spicifer
- Cladosporium werneckii
How is Eumycotic Mycetoma diagnosed?
- Clinical Diagnosis:
- Granules in exudate
- Laboratory Diagnosis:
- Direct examination of exudate or crushed granules
- Demonstrate hyphae with or without spores
- Culture examination:
- Grow on Sabouraud Dextrose agar with or without antibiotics
- Identification difficult
- Direct examination of exudate or crushed granules
What is the Epidemiology of Eumycotic Mycetoma?
- Not a contagious disease
- Wound contamination by soil or other infectious material
What is the Treatment for Eumycotic Mycetoma?
- Most attempts are unsuccessful
- Surgical Removal
- Iodides
- Amphotericin B
- 5-Fluorocytosine
- Thiobendazole
- Ketoconazole
What is Sporotrichosis?
- Caused by: Sporothrix schenckii
- Disease or horses, dogs, cattle, fowl, rats, hamsters, humans, mules, cats, camels, swine, mice, and primates
- Chronic and granulomatous
- Usually subcutaneous, rarely systemic
- Chronic and granulomatous
What is the Prevalence of Sporotrichosis?
- Sporadic cases in endemic areas
- Ubiquitous saprophyte of plant material, esp. sphagnum or peat moss
- Primarily a wound infection
What is the Pathogenesis of Sporotrichosis?
- Proteases -hydrolyses stratum corneum
- CMI response responsible for tissue reaction
- Cell contains lipid, melanin, peptide-rhamnomannan
What is the clinical manifestation of Sporotrichosis?
- Subcutaneous abscesses - Most Common
- Small granulomas at site of wound
- Lesions most often on extremities
- Nodules ulcerated with brownish-red exudate
- Lymphangitis
How does Sporotrichosis affect horses?
- Streptothricosis - Dermatophilus congolensis
- Glanders - Burkholderia mallei
- Ulcerative lymphagitis - Coryne pseudotuberculosis
- Epizootic lymphangitis - Histoplasma capsulatum var. farciminosusm
How is Sporotrichosis Diagnosed?
- Laboratory:
-
Microscopic Examination of exudate
- Gram Stain
- New Methylene Blue
- Cigar Bodies (yeast cells)
- Dogs, horse, human - few or none
- Cats and Dogs testicular lesions - many cigar bodies
-
Cultural examination
- BA at 37C - Yeast phase
- Potato dextrose agar - black colonies
- Sabouraud Dextrose agar at 25C
- Grows in mycelial phase
- Small oval conidia on a short conidiophore
- convert mycelial to yeast phase for confirmation
-
Microscopic Examination of exudate
What is the treatment for Sporotrichosis?
- Iodides - organic or inorganic
- Amphotericin B - toxicity
- Surgery contraindicated
- May cause dissemination and increase severity
- Griseofulvin
- Ketoconazole
- Itraconazole
- 5-Fluorocytosine
What is Rhinosporidiosis?
- Caused by Rhinosporidium seeberi
- Chronic granulomatous infection of the mucous membranes of the nasal cavity
- Reported in:
- Horses
- Mules
- Cattle
- Humans
- Cat
- Dogs
- Goats
- Geese
- Ducks
What is the Prevalence of Rhinosporidium seeberi?
- Sporadic in the U.S
- More cases are seen in humans than animals in endemic areas
What is pathogenesis of Rhinosporidium seeberi?
- Likely CMI reaction
What are the Clinical Manifestations of Rhinosporidium seeberi?
- Tumorous polyp-like growth in the nasal cavity
- Single or multiple
- Soft - bleed easily
- Mucopurulent nasal discharge
- Lobulated surface - cauliflower-like
- Small white specks on the surface (Sporangia)
- General health not impaired
- Not disseminated
- Affects breathing
How is Rhinosporidiosis diagnosed?
- Laboratory
- Direct examination: squeeze out sporangia and examine on wet mount
- Round Sporangia: 300-350 micro meters with 16,000-20,000 spores (5-7 micrometers) inside
- Histopathology on biopsy of fixed tissue
- Not grown in laboratory media
What is the epidemiology of Rhinosporidiosis?
- Not contagious
- Natural habitat unknown
What is the treatment of Rhinosporidiosis?
- Surgery, but may reoccur
- Antimicrobials have no effect
- Variety of things have been tried - none highly successful
What is Candidiasis?
- Caused by: Candida spp. (usually Candida albicans)
- Usually affects digestive tract of calves and poultry; also affects dogs, cats, and horses
- Swine - skin infections and gastric ulcers
- Cattle - Associated with mastitis and abortion
What is the Prevalence of Candidiasis?
- Infections usually sporadic
- Highly fatal in poultry
What is the pathogenesis of Candidiasis
- Organisms always present in digestive and urogenital tracts
- Opportunistic pathogen
- In immunocompromised individuals
- Diabetes, malnutrition, or AIDS
- Hormonal imbalance in women - vaginal
- Antibiotic or corticosteroids therapy
- Glycoproteins, proteases, lipases, neuraminidase, adhesins
What is the clinical manifestation of Candidiasis in poultry?
- Crop Mycosis:
- Whitish-gray pseudomembrane on the mucosa with many yeast cells
What is the clinical manifestation of Candidiasis in calves?
- Infections o abomasum associated with antibiotic over therapy
What is the clinical manifestation of Candidiasis in swine?
- Gastric ulcers
What is the clinical manifestation of Candidiasis in Dairy Cows?
- Prolonged antibiotic therapy following mastitis
What is the clinical manifestation of Candidiasis in dogs?
- Systemic infections have been reported
How is Candidiasis diagnosed?
- Laboratory Diagnosis:
- Direct Examination
- Clear scraping in 10% KOH
- Gram stain scraping
- Cultural Examination
- Yeast cells on Sabouraud Dextrose agar, final identification difficult
- Commercial test kits
- Direct Examination
What is the Epidemiology of Candidiasis?
- Humans: transmitted at birth
- Animals:
- Likely at birth
- Direct animal to animal contact when in close confinement
- Endogenous
What is the Treatment for Candidiasis?
- Discontinue antibiotic and/or steroid therapy
- Nystatin ointment topically
- Amphotericin-B
- In Poultry 1:2000 copper sulfate in the drinking water
- Miconazole, itraconazole, fluconazole
- Flucytosine
What are the characteristics of Malassezia pachydermatis?
- Part of the normal flora of canine ear
- Antibiotic therapy for infections caused by other microorganisms (Pseudomonas aeruginosa)
- First described on he Rhinoceros - skin lesions
How is Malassezia pachydermatis cultured?
- Grows on;
- Blood agar at 37C
- Sabouraud Dextrose Agar
- Dermatophyte Test medium
- Gram stain:
- Typical budding yeast cells, some appearing like peanut shells
How is Malassezia pachydermatitis treated?
- Like C. albicans (Both cause Cndidiasis)
- Nystatin ointment topically
- Amphotericin-B
- Miconazole, itraconazole, fluconazole
- Flucytosine
What is Zygomycetes (phycomycetes)?
- Granulomatous diseases
- Affect a wide variety of tissues
- Important Phycomycetes
- Mucor sp.
- Rhizopus sp.
- Absidia sp.
- Mortierella sp. - cases of abortion
- Rhizomucor sp.
What is the pathogenesis of Zygomycetes?
- Tend to occur in individuals who are suffering from another primary condition
What are the Clinical Manifestation of Zygomycetes in horses?
- Ulcers and granulomatous lesions on lower leg
- Reported to cause granulomatous lesion at the muco-cutaneous junction of the mouth and nostril
What are the Clinical manifestations of Zygomycetes in other species?
- Dog:
- ulcers on the leg
- Otitis
- Calves: Abomasal ulcers
- Sheep: Respiratory infections
- Birds: Respiratory infections
- Cattle:
- Placental lesions
- Mycotic rumenitis
- Abortion - Mortierella sp.
How is Zygomycetes diagnosed?
- Clinical:
- Usually made at necropsy
- In living animal or at necropsy, biopsy or smear from infected tissue
- Should demonstrate aseptate, broad hyphae
- Laboratory:
- Direct Examination
- Aseptate, broad hyphae in smear from lesion
- Histopathology on necropsy or biopsy tissue
- Direct Examination
What are the predisposing factors for Zygomycetes?
- Horses standing in water or mud (OKA: “Leaches”)
- Cattle: overload of the rumen and rumenitis with resulting invasion of ruminal wall with the fungus
- Result in rupture of the rumen
- Neoplasia
- Immunosuppressive therapy or disease
What is the treatment for Zygomycetes?
- Surgery
- Amphotericin - B
What is Aspergillosis?
- Systemic Mycoses
- Caused by: Aspergillus spp.
- Primarily infections of the respiratory tract
- Can also affect eyes skin, meninges, reproductive tract
- Infections in mammals are rare
- Commonly see infections in birds - domestics and wild
- Common bread mold
What is the pathogenesis of Aspergillosis?
- Most infections likely contracted by inhalation of spores
- Adhesins, lipases, proteases
What are the clinical manifestations of Aspergillosis in birds?
- Brooder pneumonia
- Young birds are very susceptible
- Septicemia and fungus throughout body
- Very high morbidity and mortality
- Chronic air sacculitis in wild birds
- Fungus grows in air sacs - sporulates
What are the clinical manifestations of Aspergillosis in horses?
- Nasal sinus infections
- Meningeal involvement
- Generalized infection - rare
- Diarrhea in young horses - rare
- Abortions in horses have been reported - rare
What are the clinical manifestations of Aspergillosis in Cattle?
- Multiple granulomas in the lungs
- Abortions
- Retained placenta
- Placenta thickened and leathery
What are the Clinical manifestations of Aspergillosis in other animals?
- Pulmonary granulomas
- Dogs, cats, sheep
- Disseminated infection
- dogs
How is Aspergillosis diagnosed?
- Use caution when cultured
- a ubiquitous saprophyte - make sure you have not cultured a contaminant
-
Direct microscopic examination
- Demonstrate septate hyphae
- May see sporulation in air sacs of birds like that seen on agar
What is the culture of Aspergillosis?
- Sabouraud Dextrose agar
- Black = A. niger
- Green/yellow = A. flavus
- Bluish-green = A fumigatus
- Gray = A fumigatus
- Pink/Yellow/Orange = A. glaucus
- Lacto-phenol-Cotton Blu tease mount
- Demonstrate typical morphology
What is the treatment for Aspergillosis?
- Not practiced in birds
- Best to follow good sanitary measures to prevent Brooder pneumonia
- Other animals - Poor prognosis
- Ketoconazole
- Nystatin
- Amphotericin - B
- 5-Fluorocystine
