Unit 4 - Fungi causing internal (systemic) mycoses Flashcards
Where are Aspergillus species common in?
air, soil, and animal feeds
What Aspergillus species is the most common cause of infection?
Aspergillus fumigatus
What does Aspergillus cause in cattle?
pulmonary and cutaneous infectino, abortions, rumenitis, gastritis, and mastitis
What does Aspergillus cause in horses?
associated with abortion, guttural pouch infection, diarrhea in foals
What does Aspergillus cause in dogs?
frontal sinus infection
What does Aspergillus cause in cats?
pulmonary disease
What does Aspergillus cause in birds?
brooder pneumonia, respiratory disease in captive penguins and commercial poultry, and crop mycosis in commercial turkey flocks
What does Aspergillus look like when it grows?
wooly, dense, pigmented green, bluish-green, olive, or yellowish-green
What does Aspergillus grow on?
SGA and BAP
How is Aspergillus transmitted?
via feed in commercial poultry, inhalation or ingesion of spores
How is Aspergillus infection treated in pet birds and raptors?
Miconazole and other imidazole compounds
What is the perfect state of Cryptococcus neoformans?
Filobasidiella neoformans in the Basidiomycota along with the mushrooms and toadstools
What does Cryptococcus neoformans have a pedilection for?
the brain and meninges
What is the natural habitat for Cryptococcus neoformans?
it is clasically associated with dessicated pigeon feces, some trees that have pockets of rotted material
How do dogs, cats, and humans get Cryptococcus neoformans infections?
it is readily inhaled and there is usually pulmonary infection
If infection by Cryptococcus neoformans in dogs, cats, and humans becomes disseminated, what happens?
meningoencephalitis is the msot common characterization - fever and severe headaches in humans
What does Cryptococcus neoformans infect in cattle?
mammary tissue and adjacent lymph nodes
What does Cryptococcus neoformans cause in horses?
nasal discharge, respiratory distress due to nasal granuloma formation
What do colonies of Cryptococcus neoformans look like?
cream-colored to tan, moist, glassy, mucoid colonies that are typical of yeasts - brown colonies on seed agar
What is the morphology of Cryptococcus neoformans?
a heavy mucopolysaccharide capsule surrounds the cells in tissues - the capsule is usually very thin on culture media but very large and impressive when present in smears
How is Cryptococcus neoformans diagnosed?
PCR-testine, direct examination with India ink, ID from culture, and serodiagnosis
What is the perfect state name for Blastomyces dermatitidis?
Ajellomyces dermatitidis
What does Blastomyces dermatitidis cause?
North American blastomycosis, a chronic, granulomatous, and suppurative infectionof humans and domestic animals
What is the morphology of Blastomyces dermatitidis?
it is dimorphic
When does the yeast phase of Blastomyces dermatitidis occur?
in tissues and at 37 degrees C on rich media
What is the yeast phase of Blastomyces dermatitidis characterized as?
thick walled, budding on a broad base and large
When is the mycelial phase of Blastomyces dermatitidis present?
on SGA at 25-30 C
What is mycelial phase of Blastomyces dermatitidis characterized as?
conidia are borne laterally on conidiophores or terminally on hyphae
Where is Blastomyces dermatitidis confined to?
the US and Canada
What is the natural habitat of Blastomyces dermatitidis?
moist soil that frequently has a combination of animal feces, insect parts, and high organic matter which is usually moist, shaded from direct sunlight, and has a pH of less than 6
What is infection with Blastomyces dermatitidis usually associated with?
activity in low lying areas around reservoirs, dams, and rivers
What does Blastomyces dermatitidis usually start as?
pulmonary infection
What does the pulmonary infection due to Blastomyces dermatitidis disseminate to?
it disseminates via a hematogenous route and produces granulomatous infection of skin and internal organs
What immunity is associated with Blastomyces dermatitidis infection?
cell mediated immunity
How do you diagnose a Blastomyces dermatitidis infection?
with typical broad-based budding yeast cells from tracheal wash or histopathology sections
How do you treat Blastomyces dermatitidis infections?
Stilbamidine or amphoteracin B, and Ketaconizole
What do Coccidioides immitis and Coccidioides posadasii cause?
valley fever and chronic disseminated lesions
What is the morphology of Coccidioides immitis and Coccidioides posadasii?
in pus and granulation tissue they appear as spherical bodies or sporangia
What do Coccidiodes immitis and Coccidiodes posadasii develop in culture?
hyphae - which are very dangerous for lab workers
Where is valley fever endemic?
in the US and San Joaquin Valley of California
Where is Coccidiodes immitis confined to?
California and Northern New Mexico
Where is Coccidiodes posadasii found?
in CA, TX, AZ, UT, NM, NV, and Central and South America
What is the pathogenesis of Valley Fever?
- Desert rodents excrete large numbers of the spherules in their feces around their burrows. 2. The spores germinate and the fungi multiply in nearby soil after it rains 3. When the ground dries, arthrospores are formed within the hyphae and these are blown about in the dust 4. Animals grazing these areas and dogs sniffing rodent burrows may inhale large numbers of arthrospores
What does Coccidiodes immitis and Coccidiodes posadasii cause in cattle and sheep?
it causes benign disease of the lymph nodes of the chest
What lesions does Coccidiodes immitis and Coccidiodes posadasii cause in dogs?
granulomatous lesions in the lungs leading to debilitation and death
What does Coccidiodes immitis and Coccidiodes posadasii cause in humans?
valley fever - the pulmonary form of infection
How is Coccidiodes immitis and Coccidiodes posadasii infection treated?
with Amphotericin B
What disease to Histoplasma capsulatum cause and where?
generalized disease involving the liver, spleen, bone marrow, lungs, and other tissues
What is the morphology of Histoplasma capsulatum?
dimorhic fungus
What is the morphology of Histoplasma capsulatum in tissues and 37 degrees C?
it is round to oval, single or budding yeast cells (can be seen in monocytes but also in PMNs and giant cells)
What is the morphology of Histoplasma capsulatum at room temp?
it is typically mold-like mycelial organism at 2-4 weeks with 2 spores - microconidia and tuberculate chlamydospores
What does the colony of the mycelial phase of Histoplasma capsulatum?
it is white and cottony but may be quite variable and range from brown to slate gray
Where is disease caused by Histoplasma capsulatum endemic to?
the Mississippi and Ohio River valley
Where is Histoplasma capsulatum typically isolated from?
soil especially where heavy contamination with bird droppings
How is Histoplasma capsulatum transmitted?
inhalation of airborne spores which are then phagocytized and spread to other organs via migrating mononuclear cells
What disease is associated with Histoplasma capsulatum?
splenomegaly, hepatomegaly, anemia, emaciation in disseminated disease - CNS, bone marrow, kidneys, and skin may be involved
How is Histoplasma capsulatum diagnosed?
via demonstration and growth of the organism from tissues or antigen or antibody detection from urine or blood samples is also performed
What is histoplasmin?
a skin test antigen for delayed type hypersensitivity
What immunity is associated with Histoplasma capsulatum?
cell mediated immunity
How is Histoplasma capsulatum infection treated?
Amphotericin B followed by itraconazole
What does Histoplasma capsulatum var farciminosum cause?
epizootic lymphangitis or African farcy in horses and mules
What is the morphology of Histoplasma capsulatum in pus?
oval, yeast-like cells
Where is Histoplasma capsulatum var farciminosum endemic?
in soil in parts of Africa, the Middle East, and Asia
How does Histoplasma capsulatum var farciminosum spread through the body?
It enters via wounds, spreads to the superficial lymphatic vessels and nodes particularily of the legs, chest, and neck
What lesion does Histoplasma capsulatum var faciminosum cause?
it cause the lymph nodes and channels to become swollen and rupture - the disease is chronic and progressive
How do you treat a Histpolasma capsulatum var farciminosum infection?
with Na Iodide
What is Zygomycosis?
a general term used to describe infections caused by the Zygomycetes
What lesions are involved with zygomycosis?
granulomatous and ulcerative lesions that involve the lymph nodes, respiratory, and alimentary tracts - the lymph nodes become caseocalcereous
What can Zygomycetes cause in cattle?
abortions
What do Zygomycetes look like in tissue?
coarse, non-septate, branching hyphae with rounded sporangia at their terminal portion
What are the genera of importance to Mucormycosis?
Mucor, Rhizopus, and Absidia
What do Mucor colonies look like?
dense, white to gray, cottony growth that tends to fill the tube or plate
What is the natural habitat of the Mucor species?
They are all saprophytes and occur widely in nature
How do Mucor species infect animals?
via inhalation or ingestion of spores and occasionally by traumatic implantation
How do you diagnose Mucor?
find the distinctive broad non-septae hyphae in the tissues
What is Chromomycosis?
subcutaneous infections caused by a number of dematiaceous fungi
What species get chromomycosis?
dogs, horses, and humans
What species (fungi) are involved with chromomycosis?
Hormodendrum, Cladosporium, Curvularia, Phialophora
What is the morphology of the organisms that cause Chromomycosis?
single celled or clustered, spherical, thick waled yeast cells, with a dark brown to black pigment
What does the culture of Chromomycosis causing species look like?
dark brown or black colonies
Where are the organsisms that cause Chromomycosis found?
widespread in nature
How do organisms that cause Chromomycosis enter the body?
via wounds or abrasions
What lesions does Chromomycosis cause?
produces nodular and frequently ulcerative lesions of the feet and legs with regional granulomatous lymphadenitis
What is Mycetoma?
a localized swollen lesion consisting of granulomas and abscesses which suppurate and drain through sinus tracts
What parts of the body can get mycetoma?
the skin, subcutaneous tissue, fascia, and bone
What are Actinomycotic mycetomas caused by?
species of the genus Actinomyces - not fungal
What causes Eumycotic mycetomas?
it is caused by at least 13 different species of fungi
What organisms cause Mycetomas?
Allescheria, Curvularia, and Helminthosporium
What is the morphology of the fungi that cause Mycetoma look like?
discrete, brown or black fungus embedded in a large mass of granulation tissue
