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What are infectious diseases caused by?
an organism
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What are the different organisms that can cause infection?
- bacteria
- fungi
- viruses
- parasites
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What are the different parasites that can cause infection?
- protozoa
- nematodes
- trematodes
- cestodes
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What are the different types of bacteria that cause infection?
- Ecoli
- Salmonella
- Staphylococcus
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How can we tell bacteria apart?
by shape and gram staining (red for gram - and blue for gram +)
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How can bacteria be treated?
with antibiotics
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What is mycology?
the study of fungi
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What does aerobic mean?
needs O2 to survive
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Are fungal motile?
- no
- they can cannot move on their own
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Do fungi have cell walls?
yes
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Do fungi use photosynthesis?
no they exist as saprophytes or parasites
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What does saprophytes mean?
grows on or in hosts
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Where do we find fungus?
in the environment
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Pathogenic fungus can exist in 2 forms. This means it is _____ fungi.
dimorphic
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What are the 2 forms of fungus?
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What temperature does yeast live at?
body temperature
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What temperature does mold live at?
room temperature
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Can you see mold with the naked eye?
yes
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What is the growing form of mold?
hyphae
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When hyphae become intertwined to form one large mass what is this called?
mycellum
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What color is mycellum?
green (when we see the green part of mold we are seeing the mycellum)
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What do hyphae reproduce?
spores
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What is septa?
- cross walls of hyphae
- helps us identify the species
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What kind of reproduction does mold go through?
asexual
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What are the different specialized spores mold reproduce as?
- conidiophores
- conidia
- microconidia
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Are molds resistant in the environment?
yes
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Is mold usually contagious?
no
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Can we see yeast with the naked eye?
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What does yeast look like microscopically?
- oval to spherical
- 3 - 5 u
- forms chains
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When yeast forms chains what is it called?
pseudohypae
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How does yeast mainly reproduce?
by sporulation or budding
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What are the different types of asexual reproduction?
- sporulation
- hyphae fragmentation
- budding of yeast cells
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What does budding yeast cells look like under the microscope?
a snowman or bowling pin
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Are fungal infections contagious?
not usually
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Do fungal infections produce endotoxins?
no
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What do fungal infections usually cause?
chronic infections
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What type of chronic infections do fungal infections usually cause?
granulomatous response
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What is a granulmatous response?
how the body reacts to yeast - the body builds a wall of granulomas tissue around it
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Are fungal infections really invasive and destroy the host easily?
no, they are low virulence/invasiveness
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What does virulence mean?
destructiveness in the host - how much damage it does
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What does a granulomatous reaction look like?
firm, white mass or masses
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What are the clinical signs of a granulomatous reaction?
- low grade fever
- weight loss
- leukocytosis
- +/- inappetance
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What are the predisposing factors for fungal infections?
- decreased resistance
- moist environment
- exposure to many organisms
- necrotic focus (get into damaged tissue and establish themselves)
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What can cause a decreased resistance?
- stress
- immunosuppressive drugs or diseases
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Can healthy animals fight off fungal infections?
usually
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How do we diagnose a fungal infection?
- ID by microscrop appearance of organism (cytology/biopsy)
- rarely cultured
- elisa and latex agglutination tests
- some skin tests available
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Why do we rarely culture fungal infections?
because we don't want to grow them and expose ourselves to them
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Which fungal infection do we usually culture?
dermatophytes
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What are the three classifications of fungus?
- superficial mycoses
- subcutaneous mycoses
- deep mycoses
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What is a superficial mycoses?
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Where are subcutaneous mycoses?
mucous membranes and deeper
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Where are deep mycoses?
systemically invasion - causes more serious diseases
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What are dermatophytes often called?
ringworm
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How are dermatophytes usually spread?
by direct contact
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Who do dermatophytes mostly affect?
younger animals
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What kind of species do dermatophytes often affect?
all species
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Can people get ringworm from an animal?
yes
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What are the three main dermatophytes?
- Microsporum canis
- Microsporum gypseum
- Trichophyton mentagrophytes
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Microsporum canis causes _____ of cat cases.
98%
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Microsporum canis causes _____ of dog cases.
70%
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Who does Microsporum gypseum affect?
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Who does Trichophyton mentagrophytes affect?
horses and food animals
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What are ways to diagnose dermatophytes?
- history and clinical signs
- wood lamo in dark room
- skin scraping
- trichogram
- sabouraud dextrose agar
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What color does a dermatophyte turn when you shine a wood lamp on it?
apple green - indicates Microsporum canis
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If we shine a wood lamp on a spot that we suspect could be Microsporum canis and it does not light up apple green, does that mean that the animal does not have the fungus?
no, a negative with this test does not necessarily mean it is a negative.
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What is a trichogram?
arthrospores on/in hair
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How long does it take for the wood lamp to warm up?
5 minutes
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What is the advantage to using a wood lamp?
when it shows up positive it is definitely a positive
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How do we dissolve the scales and junk off the scraping?
use KOH
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What is KOH?
potassium hydroxide
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What do we use for cultures?
DTM
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What is DTM?
dermatophyte test medium
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What is in the DTM?
phenol red indicator
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How do we do a DTM?
- place a few plucked hairs on agar
- apply cap loosely
- grow at 25 - 30 degrees celsius (room temperature)
- grow slowly 3 - 10 - 30 days
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Why do you put the cap on loosely for a DTM?
so oxygen can get in
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How often do we check the DTM?
everyday
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When we are checking the DTM, what are we looking for?
- early red color
- mycelium
- contaminants
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How early should the DTM turn red? What does it mean if it turns red late?
- within 3 - 5 days
- if it turns red after 5 days then it is a contaminant
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What does the mycelium look like in a DTM?
- white to buff (pale yellow) color
- cottony first then turns powdery
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What do contaminants look like?
black, green, or brown
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What is the difference between a DTM and a DermatoPlate-Duo?
DermatoPlate-Duo only shows color change, it does not show any growth
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What color does DermatoPlate-Due turn and when does it turn?
blue-green in 3-7 days
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How do we do a microscopic ID after the culture?
- remove a piece of the culture and place it on a slide
- stain it with lactophenol cotton blue
- examine macroconidia
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What does M. canis macroconidia look like?
- canoe shaped
- thick walls
- knob on end
- 6 or more cells inside
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What does M. gypseum macroconidia look like?
- canoe shaped
- thick walls
- no end knob
- fewer than 6 cells inside
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What does Trichophyton macronconidia look like?
- cigar shaped
- smooth, thin walls
- variable number of cells inside
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What is Dermatophilus congolensis?
a bacterium, not a fungus
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What does Dermatophilus congolensis look like on the animal?
crusty skin lesion, looks similar to ringworm
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What does Dermatophilus congolensis look like under a microscope?
- organisms in beaded chain
- look like blue railroad tracks
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What does Dermatophilosis look like?
ringworm
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What type of animals do we usually see Dermatophilosis in?
large animals
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What are other names for Dermatophilosis?
- streptothricosis
- lumpy wool
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What are sporotrichosis?
see subcutaneous nodules and ulcers
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What part of the body does sporotrichosis follow?
the lymphatic system
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What does Sporothrix schneckii look like under a microscope?
- round-oval rod shapes
- thin, clear halo
- may resemble histoplasma
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What is the normal flora in the GI and urinary tract?
Candida albicans
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What species does Candida albicans become pathogenic?
birds
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What does Candida albicans look like?
small coccoid mass with thin wall
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What is candidiasis?
an overgrowth of C. albicans
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What does candidiasis look like on a smear?
- blue with thick wall (DQ)
- blue on gram stain
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What are other names for candidiasis?
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What is the bacteria that causes white nose syndrome in bats?
Batrachochytrium dendrobatidis
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What does Batrachochytrium dendrobatidis do to bats?
causes them to wake up in the middle of winter when there is no food and they starve to death
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What percent of the bat population is down due to Batrachochytrium dendrobatidis?
80 - 97%
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What is the normal flora on the skin and in the ears?
Malassezia pachydermatis
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What can an overgrowth of Malassezia pachydermatis cause?
yeast infection in ears and on skin
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What is chromomycosis?
chronic cutaneous or subcutaneous infection
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What color fungi is chromomycosis?
black (pigmented)
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Which species do we see chromomycosis in?
- mainly seen in reptiles, amphibians, and fish
- can be seen in domestic mammals
- becoming a big problem with frogs
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Which organism causes chromomycosis?
phialophora
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What causes Blastomycosis?
Blastomyces dermatitidis
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Where in the body do we find Blastomyces dermatitidis?
in lungs, sking, and nodes
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What does Blastomyces dermatitidis look like?
large yeast with thick wall and often seen budding
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How do we diagnose Blastomycosis?
- aspirate
- see chronic inflammation
- ELISA/skin tests available
- rarely cultured
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What causes histoplasmosis?
Histoplasma capsulatum
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Where do we find Histoplasma capsulatum?
in lungs and nodes
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Where in the enviornment do we find Blastomyces dermatitidis and Histoplasma capsulatum?
river valleys
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What does histoplasma look like under a microscope?
- small yeast
- thick wall
- seen in cytoplasm of macrophages
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What causes cryptococcosis?
Cryptococcus neoformans
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Where do we find cryptococcus neoformans?
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What does cryptococcosis look like?
- single, large, thick walled yeast
- surrounded by non-staining wide gelatinous capsule
- may see budding
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What causes coccidiodomycosis?
Coccidiodes immitis
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What is another name for coccidiodomycosis?
valley fever
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Where in the country do we see Coccidiodoes immitis?
dry areas - SW U.S.
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Where in the body do we see Coccidiodes immitis?
lungs but may spread to other sites like bones
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What does Coccidiodes immitis look like under a microscope?
- thick wall
- endospores inside (little things inside)
- see spherules (large yeast)
- do not bud
- may not be in focus with segs (out of focus when segs are in focus, in focus when segs are out of focus)
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What causes aspergillosis?
Aspergillus fumigatus
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Where do we find Aspergillus fumigatus in the body?
nasal passages or lungs
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What can Aspergillus fumigatus cause in ruminants?
abortions
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Which species is Aspergillus fumigatus pathogenic in?
birds
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What does Aspergillus fumigatus look like under the microscope?
see hyphae (not yeast)
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What causes Aspergillus fumigatus?
poor ventilation and stress
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What is mycotoxicosis?
toxins soem fungi produce
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Where do we find mycotoxicosis?
common on grain and forage
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What problems do mycotoxicosis cause?
- CNS (depression, convulsions)
- hepatitis
- abortion
- death
- neoplasia
- chronic exposure
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What do we need in order to diagnose Mycotoxicosis?
feedstuff
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How can we avoid mycotoxicosis?
don't feed moldy food to animals
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What is this?
Aspergillus fumigatus
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What is this?
Aspergillus fumigatus
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What is this?
Aspergillus fumigatus hyphae with spores
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What is this?
Blastomyces dermatitidis
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What is this?
Candida albicans
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What is this?
Coccidiodes immitis
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What is this?
Coccidiodes immitis
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What is this?
Coccidiodes immitis
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What is this?
Cryptococcus neoformans
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What is this?
Cryptococcus neoformans
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What is this?
Cryptococcus neoformans
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What is this?
Cryptococcus neoformans budding
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What are the "railroad track" looking things?
Dermatophilus congolensis
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What is this?
Histoplasma capsulatum
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What is this?
Malassezia pachydermatis
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What is this?
Microsporum canis
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What is this?
Microsproum gypseum
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What is this?
Phialophora
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What is this?
Sporothrix schneckii
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What is this?
Sporotrichosis
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What is this?
Trichophyton mentagrophytes
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