Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Vet Derm Review > Fungal diseases > Flashcards

Fungal diseases Flashcards

You may prefer our related Brainscape-certified flashcards:
Dermatology Board Prep flashcards
1
Q

What dog breed has a higher frequency of Malassezia pachydermatis in the nose, mouth, vulva and axilla compared to other species?

A

Basset hounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What type of immunity is required to clear Coccidioides infection?

A

cell-mediated immunity (T-lymphocytes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the most common dermatophyte pathogen in people? Clinical presentation?

A

Trichophyton rubrum; onchomycoses (toe nail fungus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the types of Lagenidiosis and associated clinical signs?

A

cutaneous - ulcerative, nodular, mass-like cutaneous lesions with draining tracts; pelvic limb edema; local, thoracic, or abdominal lymphadenopathy; rupture of infected great vessels in the abdomen may result in hemoabdomen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the mechanism of action of terbinafine?

A

inhibits fungal sterol biosynthesis - reversibly inhibits the membrane-bound enzyme squalene epoxidase in a concentration-dependent manner –> prevents conversion of lanosterol to cholesterol and/or ergosterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Mode of transmission of Cryptococcus?

A

inhalation of basidiospores from environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

T/F: Oomycosis is considered zoonotic.

A

False - infective stage is the zoospore – Does not form in tissue, only standing water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

T/F: It is difficult to culture organsisms that cause Hyalohyphomycosis.

A

False - readily isolated on routine culture; further identification based on colony and conidial morphology and PCR and sequencing of ribosomal RNA genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Major clinical signs of histoplasmosis

A

cough, tachypnea, organomegaly, gastrointestinal signs, pallor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Mechanism of action of lufenuron?

A

benzoylphenylurea drug that disrupts chitin synthesis – chitin is a critical component of the exoskeleton of arthropods (& outer cell wall of fungi)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

T/F: histoplasma capsulatum can be seen on cytology from affected tissues.

A

True - usually intracellular within mononuclear phagocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the optimal therapy for cats with cryptococcosis with CNS involvement?

A

amphotericin B and 5-flucytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Characteristics of yeast form of Sporothrix spp.

A

cell wall contains glucans and galactose-containing polysaccharides and melanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What the two types of Pythiosis and associated clinical signs?

A

cutaneous - ulcerative, nodular, mass-like cutaneous lesions with draining tracts; gastrointestinal form - weight loss, anorexia, vomiting, diarrhea, hematochezia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a unique finding on dermoscopy in cats with dermatophytosis?

A

opaque, slightly curved or broken hairs with a homogenous thickness (“comma hairs”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Malassezia overgrowth is favored by skin diseases with altered stratum corneum barrier function through aberrant cornification. What diseases are implicated in this category?

A

zinc-responsive dermatosis, hepatocutaneous syndrome, endocrinopathies (hypothyroidism and hyperadrenocorticism), atopic dermatitis, congenital ichthyosis, thymoma-associated dermatosis, paraneoplastic alopecia, feline facial acne

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the best diagnostic test for Coccidioidomycosis?

A

serum antibody

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do keratinocytes recognize Malassezia antigens?

A

through Toll-like receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the most common systemic mycosis of cats?

A

Cryptococcosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Most commonly isolated species of Candida to cause disease in dogs and cats

A

Candida albicans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Subcutaneous dermatophytic infections have been most commonly reported in what breed(s)?

A

Persian cats and Yorkshire terriers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Geographic distribution of Candida spp.

A

worldwide – normal inhabitants of the gastrointestinal, urogenital and cutaneous flora; can slo be isolated from soil, inanimate objects, and hospital environments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the Blastomyces antigen test detect?

A

cell wall galactomannan antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

T/F: A positive fungal culture with Candida is diagnostic as the cause of disease.

A

False - commensals of mucosa, so positive cultures should be interpreted in light of clinical signs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Environmental conditions that favor Sporothrix species

A

humid condition (92-100% humidity), temperatures between 25-30 degrees C, prefer moist soil that is rich in decaying vegetation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

T/F: Cats may still have hairs that glow with a Wood’s lamp after clinical cure of dermatophytosis

A

True - the pteridine pigment remains detectable on the tips of the hairs as they grow out, even though the infection may be eliminated (will remain after hairs are culture negative)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Histopathologic features of Coccidioidomycosis

A

neutrophils, macrophages, fibrosis, with occasional endosporulating or non-endosporulating spherules; multinucleated giant cells can contain spherules; often no spherules are found**

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

There is moderate evidence for treatment of Malassezia dermatitis in dogs for what treatment(s)?

A

3% chlorhexidine shampoo, ketoconazole 5-10 mg/kg SID-BID, itraconazole 5 mg/kg SID or 2 consecutive days/week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does Coccidioides grow in the environment? In tissue?

A

exist in the environment as mycelium – haploid, multinucleated, barrel-shaped arthroconidia (arthrospores) that alternate with smaller, thin-walled, nonviable cells; in tissue - exist as spherules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is seen on histopathology with a fungal kerion?

A

granuloma or pyogranuloma formation, often with fragments of hair shafts containing fungal spores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the preferred medium for the isolation and quantification of Malassezia pachydermatis?

A

Modified Dixon’s agar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Cytological characteristics of Coccidioides

A

granulomatous to pyogranulomatous inflammation with spherules – round, deeply basophilic, double-walled, slightly crinkled structures; spherules are generally low in numbers; endospores may be identified where spherules have ruptured and can be found within phagocytes - endospores are 2-5 um in diameter, surrounded by a thin, nonstaining halo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Opportunistic fungal infection caused by pigmented hyphal or yeast forms

A

phaeohyphomycosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

T/F: Animals affected with Pythiosis are usually immunocompromised.

A

False - usually immunocompetent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Eumycotic mycetoma histopathological characteristics

A

nodular masses of granulomatous inflammation with fibrosis and exudate containing embedded granules of masses of septate, branching fungal hyphae (0.2-6um in diameter), bordered by hyaline eosinophilic Splendore-Hoeppli material arranged radially or smoothly contoured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

T/F: The Aspergillus glactomannan antigen ELISA assay is positive in some animals with hyalohyphomycosis.

A

True - with paecilomycosis (Paecilomyces) – due to antigen cross-reactivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

T/F: Blastomyces can be seen on cytologic specimens from affected tissues.

A

True (usually) - Blastomyces dermatitidis yeasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Clinical signs of iodine toxicity

A

ocular and nasal discharge, dry scaly coat, vomiting, depression and collapse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

T/F: Lime sulfur is sporicidal against dermatophyte spores

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Under what conditions does Histoplasma capsulatum grow in the environment?

A

moist, humid, nitrogen-rich soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the most common lipid-dependent Malassezia organism isolated from the ear canals of cats?

A

Malassezia nana

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

T/F: Cryptococcus is zoonotic.

A

False - pets may act as a sentinel species for humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are possible reasons for a false positive Dermatophyte PCR test?

A

fomite carriage or nonviable fungal organisms from a successfully treated infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Size of pythium insidiosum on histopathology

A

wide (2-7 um, 4 um mean), have nonparallel walls, are infrequently septate and occasionally branch at right angles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What breed of dog may be predisposed to phaeohyphomycosis and hyalohyphomycosis?

A

german shepherd dogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

T/F: Malassezia yeasts are the most abundant fungal organisms on healthy canine skin.

A

False - filamentous contaminants from the environment (Alternaria, Cladosporium, Epicoccum) were predominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Describe the pathogenesis of histoplasmosis

A

microconidia are inhaled from environment –> microconidia transition to unicellular yeast, which replicates by budding –> fungus binds to CD11-CD18 integrins on alveolar macrophages and is phagocytized –> replicates within macrophages –> destroys them and recruits more inflammatory cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Mechanism of action of griseofulvin?

A

inhibits nucleic acid synthesis and cell mitosis by arresting division in metaphase; interferes with function of spindle microtubules; causes morphological changes in fungal cells and may antagonize chitin synthesis in fungal cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Most common serum biochemical abnormality with histoplasmosis

A

mild to severe hypoalbuminemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

In which species is disseminated cryptococcosis more common: dogs or cats?

A

dogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Mechanism of action of ketoconazole?

A

similar to itraconazole - inhibits lanosterol 14-alpha demethylase –> leads to ergosterol depletion and accumulation of aberrant and toxic sterols in the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What stain highlights melanin in the cell wall of organisms implicated in phaeohyphomycosis?

A

Fontana-Masson stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Cytological characteristics of histoplasma capsulatum

A

yeasts are 2-4 um in diameter, oval, have a basophilic center and are surrounded by a clear halo (similar in size to Sporothrix spp but different in shampe)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Which fungal disease can manifest as cutaneous lesions, lymphocutaneous lesions, or multifocal lesions?

A

Sporotrichosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Appearance of Blastomyces dermatitidis on cytology

A

yeasts that are 8-15 um in diameter, have a thick, refractile cell wall, and exhibit broad based budding (daughter cells are nearly as large as the parent cell when they detach)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What species of fungi implicated in hyalohyphomycosis is resistant to Amphotericin B?

A

Paecilomyces spp. - are susceptible to azoles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is the immunologically active portion of the cell wall of dermatophytes?

A

glycopeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

T/F: Dermatophytes can be part of the normal skin microbiome of dogs or cats.

A

FALSE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What type of immunity is required to clear blastomyces infection?

A

natural immunity - neutrophils and alveolar macrophages can clear conidia; once in yeast form - control of infection also depends on T lymphocytes -> stimulate macrophages to kill the yeasts (cell-mediated immunity); humoral immunity is not essential for resolution of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

T/F: Dermatophytosis acquired from environment alone is rare.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Opportunistic fungal infection caused by non-pigmented hyphal forms

A

hyalohyphomycosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Which antifungal drug has the poorest antifungal activity against dermatophytes: fluconazole, griseofulvin, itraconazole, ketoconazole, or terbinafine?

A

fluconazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Which antifungal drug has the lowest MIC for dermatophytes: fluconazole, griseofulvin, itraconazole, ketoconazole, or terbinafine?

A

terbinafine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

T/F: Pythium insidiosum hyphae are visible on routine H&E sections.

A

False - are identified as clear spaces surrounded by a narrow band of eosinophilic material; Need GMS stain to visualize

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

T/F: Serology alone should not be used as a basis for diagnosis of lagenidiosis.

A

True - serologic testing can cross-react with pythium and other fungal or nonfungal infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Opportunistic fungal infection characterized by fibrosing granuloma with black or white tissue grains (pigmented or nonpigmented fungi)

A

eumycotic mycetoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Cytological characteristics of Phaeohyphomycosis

A

Dark-walled, irregularly septate hyphae or yeast-like cells, solitary or in small groups or chains; pyogranulomatous inflammation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Cytological characteristics of Rhinosporidiosis

A

pyogranulomatous to suppurative inflammation, numerous immature to mature R. seeberi endospores; endospores are round to oval (10-15 um) and have a thick cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What treatment has shown promise in the prevention of Malassezia otitis externa associated with allergic skin disease?

A

twice weekly topical hydrocortisone aceponate application

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What genera of fungi have been associated with phaeohyphomycosis?

A

Alternaria, Bipolaris, Cladophialophora, Curvularia, Exophiala, Fonsecaea, Moniliella, Phialophora, Ramichloridium, Ulocladium, Scolecobasidium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What is the possible mechanism of Malassezia’s resistance to azoles?

A

reduced affinity due to alterations in drug target enzyme by increased expression of the target gene (ERG11) encoding this enzyme or by increased efflux by overexpression of genes encoding membrane transport proteins of the ABC transporter (CDR1/CDR2) or the major facilitator (MDR1) superfamilies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

How long after exposure to dermatophytes do clinical lesions appear?

A

1-3 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Zoophilic dermatophytes that affect the pig?

A

Microsporum nanum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

T/F: Organisms are usually scarce with aspergillosis.

A

False - plentiful and characterized by broad (3-6 um) septate, dischotomously branched hyphae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What testing for Lagenidiosis provides a defnitive diagnosis and allows differentiation beetween the two pathogenic species?

A

culture followed by PCR and rRNA gene sequencing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Aspergillus spp. are intrinsically resistant to what antifungal drug?

A

fluconazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

T/F: Absorption of fluconazole is enhanced by giving it with food.

A

False - it is water soluble

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What is the primary reservoir of histoplasma capsulatum?

A

intestinal tracts and guano of bats; can also be found in high concentrations in decaying avian guano

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Microscopic appearance of macroconidia of Microsporum canis

A

Spindle or canoe-shaped, >= 6 cells with thick walls with outer spines on surface and terminal knob; Young colonies may have <6 cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

T/F: Both immediate and delayed-type hypersensitivities have been documented against Malassezia antigens.

A

True - delayed reactions reported in Basset hounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

T/F: Cats are more susceptible to Sporotrichosis than dogs.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Major clinical signs of Sporotrichosis

A

cutaneous nodules or draining skin lesions, lymphadenopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What species of dermatophyte causes prominent scaling but minimal alopecia because it infects surface keratin but does not invade hair?

A

Microsporum persicolor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

Adverse effects documented with lime sulfur treatment?

A

drying of the footpads, loss of hair on the ears, drying of the hair coat, yellow discoloration of white cats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

Phaeohyphomycosis histopathological characteristics

A

foci of granulomatous, pyogranulomatous or lymphocyte-rich granulomatous dermatitis and panniculitis containing pigmented fungal organsism in small aggregates throughout the lesion. Hyphae are septate, 2-6um wide, and branched or unbranched. Fungal elements are usually intracellular within epithelioid macrophaes and multinucleated giant cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

T/F: Malassezia has a high risk of zoonosis.

A

False - overall quite low unless severely immunocompromised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

____ are cylindrical, thread-like strctures of fungi that grow at the tips and can either branch or fork.

A

Hyphae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What is the treatment of choice for eumycotic mycetoma?

A

aggressive surgical excision of infected tissue; adjunctve medical therapy following surgery with itraconazole, voriconazole, posaconazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

Microscopic appearance of macroconidia of Microsporum gypseum

A

rowboat shaped, each containing <6 cell with thin walls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

T/F: Cats without a breed predilection for Malassezia overgrowth or an underlying hypersensitivity disorder most often have visceral neoplasia or other serious internal disease.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What similarities are possible on histopathology between pemphigus and dermatophytosis?

A

acantholytic intraepidermal pustules and interface dermatitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What causes the color change in Dermatophyte Test Medium when dermatophytes are present?

A

(yellow to red) - result of pH change triggered by fungal growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Treatment of choice for feline cryptococcosis

A

fluconazole - good penetration to brain, eye, and urinary tract; other treatment options include itraconazole, ketoconazole, amphotericin B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

Best treatment for blastomycosis in dogs

A

itraconazole, also amphotericin B is effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What is the infective form of dermatophytes?

A

arthrospore - formed by fragmentation of fungal hyphae into very small infective spores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

______ are responsible for asexual reproduction of fungi and are nonmotile spores generated by mitosis and can come in many shapes and sizes.

A

Conidia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

Black-grain eumycotic mycetomas are most often caused by what fungi?

A

Curvularia spp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

T/F: Antibiotic use is an independent risk factor for development of Malassezia dermatitis.

A

False - never been reported in any published studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

T/F: Coccidioides is zoonotic.

A

False - pets may act as a sentinel species for humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

T/F: Gentamicin has antifungal activity against Malassezia pachydermatis.

A

True - so does netilmicin, tobramycin, and framycetin (in vitro susceptibility)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

What is the infective form of Rhinosporidium seeberi?

A

small round spore (7-15 um) that develops in tissues into large (100-450 um) spherical bodies known as sporangia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

T/F: Serology alone is diagnostic for pythiosis.

A

True - highly sensitive and specific ELISA for anti-Pythium insidiosum antibodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

What is the purpose of topical therapy in treatment of dermatophytosis?

A

to decrease the infectious, contagious and zoonotic risks by disinfecting the hair coat and minimizing contamination of the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

For what fungal disease has localized hyperthermia been used with some success? Why?

A

Sporotrichosis - Sporothrix spp. are temperature sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What do dermatophytes produce that digest keratin into usable peptides and amino acids?

A

endoproteases (subtilisins and fungalysins) and exoproteases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

What fungal organisms multiply by broad-based budding?

A

Malassezia, Blastomyces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

What is the clinical presentation of a fungal kerion?

A

single or multiple erythematous, alopecic, dome-shaped, exudative nodules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

Clinical signs of phaeohyphomycosis

A

cutaneous nodules, nasal mass - may appear grossly pigmented (often confused with melanomas)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

Histopathologic features of Candidiasis

A

spongiotic neutrophilic pustular inflammation, parakeratosis, ulceration with exudation - Candida present in superficial exudates; Yeasts, pseudohyphae, and hyphae are best visualized with PAS or GMS stains: yeasts are more numerous on the surface of the lesions, whereas hyphae and pseudohyphae extend into the epidermis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

Most common species of Cryptococcus to infect dogs?

A

Cryptococcus neoformans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

T/F: When a hair enters telogen, fungal growth of dermatophytes stops.

A

True - infection continues with keratin production, when a hair enters telogen, keratin production stops and fungal growth ceases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

What cytokine is important in clinical cure of dermatophytosis and protection against re-infection?

A

interferon-gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

Species of aspergillus associated with sinonasal aspergillosis

A

Aspergillus fumigatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

Most common geophilic dermatophyte to infect animals and humans after contact with contaminated soil?

A

Microsporum gypseum complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

Characteristics of Candida spp. organisms

A

reproduce by budding; yeasts are small (3-6 um) and ovoid (blastospores) –> budding results in formation of new yeast cells, pseudohyphae (chains of elongated yeast cells), and true septate hyphae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

Does serology for Pythium insidiosum detect antigen or antibody?

A

Antibody

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

Describe the pathogenesis of Sporotrichosis

A

cutaneous inoculation –> converts to yeast form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

White-grain eumycotic mycetomas are most often caused by what fungi?

A

Pseudallescheria boydii or Acremonium spp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

Which is more sensitive and specific for diagnosis of Histoplasmosis: Antibody or Antigen ELISA?

A

Antigen; false positives can occur with the antibody test in endemic areas (result of exposure or previous recovery)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

Which is more sensitive and specific for diagnosis of Aspergillosis: Antibody or Antigen ELISA?

A

Antibody - negative result does not rule out disease, but a positive result is strongly supportive (for Sinonasal aspergillosis); For disseminated aspergillosis - an Aspergillus galactomannan antigen ELISA assay has high sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

What body sites are most commonly colonized by Malassezia pachydermatis in dogs?

A

perioral/lip region (81% of dogs), interdigital skin (60-70%), perianal skin/anal mucosa (55%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

What organisms associated with Zygomycosis cause cutaneous lesions similar to Pythiosis and Lagenidiosis?

A

Basidiobolus and Conidiobolus spp.

123
Q

T/F: Animals with Lagenidiosis often have nonresectable disease.

A

True - located in thorax, abdomen, or regional lymph nodes

124
Q

Histopathologic features of Lagenidiosis

A

pyogranulomatous and eosinophilic inflammation associated with broad, irregularly branching, infrequently spetate hyphae with nonparallel walls; right-angle branching is occasionally observed, scant to thin eosinophilic sleeve may be noted around the hyphae

125
Q

Zoophilic dermatophytes that affect voles? Rodents/Rabbits/Hedgehogs?

A

Voles: Microsporum persicolor; Rodents/rabbits/hedgehogs: Trichophyton mentagrophytes complex

126
Q

What antifungal drug is contraindicated to use in cats that are FIV positive?

A

griseofulvin - can cause bone marrow suppression

127
Q

T/F: Cats with FeLV or FIV have decreased fungal diveristy on their skin.

A

False - have INCREASED fungal diversity

128
Q

What is the clinical presentation of a pseudomycetoma or mycetoma?

A

nodules that fistulate, ulcerate, and drain serous to puruluent debris with tissue grains

129
Q

What species of Cryptococcus cause the majority of disease in dogs, cats, and humans?

A

Cryptococcus neoformans and Cryptococcus gatii

130
Q

Describe the environmental conditions that favor development of coccidioidomycosis

A

in endemic areas, often follows a cycle of moist conditions (required for growth of the organism in the soil), a dry period, then soil disruption by heavy rainfall, earthquakes, dust storms, prolonged droughts, or construction

131
Q

What causes hairs to have the characteristic green fluorescence with a Wood’s lamp when infected with M. canis?

A

water-soluble chemical metabolite (pteridine) located within the cortex or medulla of the hair

132
Q

T/F: Fungal culture is the gold standard for diagnosis of dermatophytosis.

A

False - no one test was identified as a gold standard - diagnosed by complementary diagnostic tests, including Wood’s lamp and trichogram, dermatophyte culture, biopsy with fungal stains for atypica infections/nodular infections

133
Q

What is the mode of action of nystatin?

A

altered cell membrane permeability mediated by preferential binding to ergosterol

134
Q

What is a zoophilic dermatophyte species?

A

adapted to living on animal hosts

135
Q

Histopathlogic features of Pythiosis

A

eosinophilic pyogranulomatous inflammation with multiple foci of necrosis, surrounded by neutrophils, eosinophils, and macrophages – organisms are typically found within areas of necrosis at the center of granulomas - on H&E are identified as clear spaces surrounded by a narrow band of eosinophilic material

136
Q

How does Sporothrix grow in the environment? In tissue?

A

hyphae in environmetal tissues; grow as yeast in tissue

137
Q

Strong evidence for treatment of Malassezia dermatitis in dogs exist for only what treatment?

A

2% miconazole/2% chlorhexidine shampoo twice weekly

138
Q

What is the primary site of infection with cryptococcosis in dogs and cats?

A

nasal cavity (pulmonary parenchymal involvement is rare)

139
Q

Mechanism of action of itraconazole

A

inhibits fungal cytochrome p450 enzyme 14-alpha demethhylase to prevent conversion of lanosterol to ergosterol (ergosterol maintains cell wall integrity and activity)

140
Q

Mode of transmission of Histoplasma

A

inhalation of microconidia from environment

141
Q

How does Blastomyces grow in environment? In tissue?

A

Environment: mycelial form - hyphae in the soil produce conidia; tissue: thick-walled budding yeast

142
Q

T/F: Malassezia pachydermatis is more susceptible to nystatin than ketoconazole.

A

False - inferior to ketoconazole and terbinafine

143
Q

What is the treatment of choice for pythiosis?

A

aggressive surgical resection of all infected tissues with wide margins followed by treatment with itraconazole and terbinafine

144
Q

Major differences between feline and canine sporotrichosis?

A

feline - usually MANY organisms present; canine - FEW organisms present; therefore FELINE SPOROTRICHOSIS is more of a zoonotic concern

145
Q

What systemic treatment options are available for dermatophytosis? Which are the most effective?

A

Itraconazole, terbinafine > Griseofulvin > Ketoconazole or Fluconazole

146
Q

What are the two polyene cyclic macrolides used in clinical practice?

A

amphotericin B and nystatin

147
Q

T/F: Most dogs and cats with cryptococcosis have underlying immunosuppressive illness.

A

FALSE

148
Q

Clinical signs of hyalohyphomycosis

A

cutaneous lesions, nasal mucosal involvement, keratitis, osteomyelitis, pneumonia, disseminated disease with involvement of lymph nodes, kidneys, liver, spleen, bone, intervertebral discs, and/or CNS

149
Q

Causative organism of Rhinosporidiosis

A

Rhindosporidium seeberi; aquatic protistan parasite - impossible to culture

150
Q

What is the treatment of choice for phaeohyphomycosis?

A

aggressive surgical resection followed by medical therapy with itraconazole or posaconazole for 3-6 months

151
Q

Describe the pathogenesis of coccidioidomycosis

A

arthroconidia are inhaled & phagocytosed by alveolar macrophages –> enlarge into a spherule (8-100 um in diameter) –> endospores develop within the spherule –> released when the spherule ruptures –> attracts neutrophils

152
Q

Histopathologic features of Zygomycosis

A

Histologic hallmark is the presence of a wide (2.5 to 25 um) eosinophilic sleeve that surrounds the hyphae**; hyphae are broad, thin-walled and occasionally septate; hyphal diameter is larger for Basidiobolus spp. and Conidiobolus spp. than for Pythium insidiosum

153
Q

T/F: Tissue specimens should be ground or macerated prior to culture when Zygomycosis is suspected.

A

False - this may destroy the organism

154
Q

What antifungal drugs are recommended to treat histoplasmosis?

A

ketoconazole, itraconazole, fluconazole, amphotericin B

155
Q

What has been reported to account for poor bioavailability of compounded itraconazole?

A

absence of cyclodextrin - carrier compound shown to improve gastrointestinal absorption

156
Q

What species of Zygomycosis typically infects mucocutaneous sites and causes sinusitis?

A

Conidiobolus

157
Q

What immune response is important for clearance of cryptococcosis?

A

cell-mediated immunity: production of Th1 type cytokines such as IL-2, TNF-alpha, IFN-gamma and a granulomatous inflammatory response

158
Q

Major clinical signs of Blastomycosis

A

fever, anorexia, cough, tachypnea, nodular or ulcerative cutaneous lesions, ocular lesions (uveitis, chorioretinitis, panophthalmitis), lameness, neurological signs

159
Q

What Malassezia species have been isolated from cats?

A

Malassezia pachydermatis, Malassezia sympodialis, Malassezia globosa, Malassezia furfur, Malassezia nana, and Malassezia slooffiae

160
Q

Why is it not recommended to treat dogs with 5-flucytosine?

A

dogs can develop toxic epidermal necrolysis within 10-14 days of initiating therapy

161
Q

Cytological characteristics of Hyalohyphomycosis

A

Fungi are nonpigmented, frequently septate, branching hyphae that are often pleomorphic with pyogranluomatous inflammation; Phialosimplex may cause yeast-like forms in tissue

162
Q

Zoophilic dermatophytes that affect the horse?

A

Microsporum equinum, Trichophyton equinum

163
Q

What species of systemic fungal diseases can be cultured in routine laboratory settings without risk to the laboratory staff? Why?

A

Cryptococcus - grows as a yeast on routine fungal media

164
Q

T/F: Cryptococcus organisms can survive and replicate within phagocytic cells

A

TRUE

165
Q

T/F: Candidiasis is most common in immunocompromised hosts.

A

True - diabetes mellitus, immunosuppressive drugs, prolonged borad-spectrum antibacterial drugs have been associated

166
Q

What is the active ingredient/compound in Lime Sulfur that is fungicidal?

A

hydrogen sulphide

167
Q

Which is more sensitive and specific for diagnosis of Coccidioidomycosis: Antibody or Antigen ELISA?

A

Antibodies (IgM or IgG)

168
Q

T/F: Sporotrichosis is zoonotic.

A

True - direct transmission can follow contact between infected cats and humans (esp cat bites or scratches)

169
Q

What antifungal drugs are recommended to treat Coccidioidomycosis?

A

fluconazole, itraconazole, ketoconazole, amphotericin B

170
Q

What is resposible for the pigment in the fungal cell wall present in phaeohyphomycosis?

A

melanin

171
Q

T/F: You cannot distinguish between pythiosis, lagenidiosis, or zygomycosis based on cytology alone.

A

True - all have a similar appearance: pyogranulomatous and eosinophilic inflammation with hyphae - broad, rarely septate with tapered, rounded ends

172
Q

Microscopic appearance of macroconidia of Trichophyton spp.

A

cigar shaped and rare; Microconidia are common and often spinal hyphae

173
Q

Diagnostics available for Pythium

A

Antibody serology, cytology, culture, histopathology, PCR assays

174
Q

Which hyphae are larger: Pythium insidiosum or Lagenidium spp.?

A

Lagenidium spp.

175
Q

Mode of transmission of Aspergillosis

A

inhalation of conidia from environment

176
Q

What are the two species of Coccidioides that cause disease?

A

Coccidioides immitis and Coccidioides posadasii

177
Q

T/F: Lagenidium spp. hyphae are visible on routine H&E sections.

A

TRUE

178
Q

T/F: Itraconazole concentrations are higher in tissue than plasma.

A

True - especially in adipose tissue and sebaceous glands (it is highly lipophilic!)

179
Q

What are the unique components of Dermatophyte Test Medium?

A

has antibiotics to suppress bacterial and contaminant fungal overgrowth and has a color indicator to aid in recognition of dermatophyte species

180
Q

Major clinical signs of Rhinosporidiosis

A

pedunculated or sessile masses within the nasal cavity (usually in the rostral third), sneezing, epistaxis

181
Q

Virulence factors of Cryptococcus

A

polysaccharide capsule; laccase (makes melanin), enzymes such as phospholipase, urease, and superoxide dismutase

182
Q

What species of Malassezia is primarily associated with the feline claw fold?

A

Malassezia slooffiae

183
Q

What treatment monitoring is recommended for daily oral terbinafine in dogs?

A

hepatic enzymes - due to reports of reversible, mild-moderate elevations of ALT and ALP

184
Q

What type of immunity is required to clear sporotrichosis?

A

cell-mediated immunity (T-lymphocytes)

185
Q

Adverse events reported with itraconazole?

A

anorexia; elevations in liver enzymes; cutaneous vasculitis (doses greater than 10 mg/kg) - dogs only

186
Q

Cytological characteristics of Cryptococcus

A

pyogranulomatous to granulomatous inflammation with numerous pleomorphic (round to elliptical, 2-20 um in diameter) yeast-like organisms; narrow-based budding, surrounded by a mucinous capsule of variable thickenss, which forms a clear or refractile halo

187
Q

T/F: Lagenidiosis has only been reported in dogs.

A

True - Pythiosis has been reported in horses, cattle, dogs and cats

188
Q

Histopathologic features of Cryptococcosis

A

can appear as cystic degenration or vauolation of the dermis/subcutis (soap bubbles); nodular to diffuse pyogranulomatous to granulomatous dermatitis and panniculitis containing numerous organisms

189
Q

What fungus grows on fungal isolation media as a white mold with production of pigmented conidia?

A

Sporothrix spp.

190
Q

Mode of transmission of Blastomyces

A

inhalation of conidia from envrionment; cutaneous inoculation

191
Q

Mode of transmission of Sporotrichosis

A

cutaneous inoculation or inhalation of conidia (minor)

192
Q

What organisms are associated with Zygomycosis?

A

Basidiobolus and Conidiobolus spp., Rhizopus, Absidia, Mucor spp.

193
Q

Opportunistic fungal infection caused by wide, infrequently septate, nonpigmented hyphae associated with pyogranulomatous and eosinophilic inflammation

A

zygomycosis

194
Q

Describe the pathogenesis of cryptococcosis

A

Inhalation of basidiospores –> in tissue the basidiospores convert to the yeast form –> replicates by forming one or two daughter cells (buds) that are connected to the parent cell by a narrow base

195
Q

Treatment of choice for sporotrichosis

A

itraconazole > fluconazole, ketoconazole; refractory disease can be treated with supersaturated potassium or sodium iodide, terbinafine, or amphotericin B

196
Q

Mode of transmission of Candidiasis

A

usually an invasion of commensal yeasts secondary to immune suppression (normal inhabitant of mucocutaneous skin and GI tract, genital tract)

197
Q

Is itraconazole fungistatic or fungicidal?

A

BOTH - at low doses it is fungistatic and at high doses it is fungicidal

198
Q

T/F: Terbinafine inhibits cytochrome p450.

A

FALSE

199
Q

Skin lesions associated with candidiasis

A

exudative and pustular to ulcerative inflammation of the lips, oral mucosa, and external ear canal; sharply delineated ulcers with erythematous borders and a malodorous surface with moist gray-white exudate; chronic lesions are thickened, alopecic, and hyperkeratotic

200
Q

Which is more sensitive and specific for diagnosis of Sporotrichosis: Antibody or Antigen ELISA?

A

Antibody - detects antibody to Sporothrix cell wall antigens; no antigen tests are currently available

201
Q

Which is more sensitive and specific for diagnosis of Blastomycosis: Antibody or Antigen ELISA?

A

Antigen; false positives can occur with the antibody test in endemic areas (result of exposure or previous recovery)

202
Q

Ketoconazole can lead to increased plasma concentrations of what drugs?

A

ivermectin, midazolam, cyclosporine (among others)

203
Q

Zoophilic dermatophytes that affect cattle?

A

Trichophyton verrucosum

204
Q

Why is phaeohyphomycosis poorly responsive to medical therapy?

A

pigmented fungi are poorly responsive to medical therapy in part because melanin is a virulence factor

205
Q

T/F: Chlorhexidine as a monotherapy for dermatophytosis is poorly effective and is not recommended.

A

True - must be combined with miconazole

206
Q

Within tissues, what cells are most important in the defense against Candida spp.?

A

neutrophils – candida blastospores are phagocytized and destroyed by neutrophils

207
Q

DDx for Sporothrix on cytology

A

Histoplasma capsulatum, Cryptococcus spp., Candida spp., Leishmania infantum (less likely Toxoplasma gondii and Neospora caninum)

208
Q

T/F: Cytologic examination of affected tissues with coccidioidomycosis has high sensitivity.

A

False - organisms may be difficult to accurately identify

209
Q

T/F: Devon rex and Cornish rex cats are prone to high carriage rates of Malassezia yeasts.

A

False - only devon rex and sphynx cats, NOT Cornish rex

210
Q

Histopathologic findings with Histoplasmosis

A

pyogranulomatous or granulomatous inflammation with intralesional yeasts; lymphocytes and plasma cells may also be present; with chronicity, may see fibrosis or mineralization (dogs)

211
Q

What is the geographic distribution of Coccidioides?

A

Southwestern US, Mexico, parts of Central and South America (NE Brazil, Argentina, Paraguay, and Bolivia)

212
Q

Which is more sensitive and specific for diagnosis of Cryptococcosis: Antibody or Antigen ELISA?

A

Antigen – detects the cryptococcal polysaccharide capsular antigen

213
Q

What is the environmental niche for Cryptococcus neoformans?

A

weathered bird (especially pigeon) guano, can also be found in decaying plant matter

214
Q

How do Candida yeast adhere to and colonize mucosa?

A

ligand-receptor and/or hydrophobic interactions; ligands = afflutinin-like family and hyphal wall protein family, receptors on the mucosal epithelial cells = E-cadherin, fibrinogen, fibronectin, thrombin, collagen, laminin, and vitronectin-binding proteins

215
Q

Zoophilic dermatophytes that affect the cat and dog?

A

Microsporum canis

216
Q

What stain helps to highlight the capsule of Cryptococcus on biopsy?

A

Mayer mucicarmine – stains organism’s capsule RED

217
Q

Why is it not recommended to culture Blastomyces dermatitidis?

A

it grows as a mycelium in the laboratory and poses a risk to lab workers

218
Q

What is the only species of Malassezia that can utilize lipid fractions from Sabouraud’s dextrose agar for growth?

A

Malassezia pachydermatis

219
Q

Under what circumstances has candiadiasis been reported?

A

compromised host resistance (diabetes mellitus, HAC, neoplasia, viral infections, cytotoxic chemo, prolonged glucocorticoid tx), factors that alter superficial keratin barrier (maceration, chronic trauma, or burns), upset normal flora (prolonged broad spectrum antibiotic therapy)

220
Q

What type of immunity is required to clear dermatophytosis?

A

cell-mediated – also involved in developing resistance to reinfection

221
Q

T/F: Cats who are seropositive for FIV and/or FeLV are at increased risk for dermatophytosis.

A

False - seropositive status alone does not increase the risk

222
Q

Does hyalohyphomycosis occur more commonly in dogs or cats?

A

dogs

223
Q

Why are Malassezia lipid dependent?

A

lack fatty acid synthase gene - cannot synthesize long-chained (C14 or C16) fatty acids de novo

224
Q

Cytological characteristics of Candidiasis

A

Candida blastospores, pseudohyphae and true hyphae can be seen in specimens from ears, skin, urine, or other bodily fluids; small yeasts (3-6 um) and ovoid (blastospheres)

225
Q

T/F: It is not recommended to culture Sprothrix spp. due to human health risks.

A

False - culture is required for definitive diagnosis

226
Q

T/F: It is difficult to culture organsisms that cause Phaeohyphomycosis.

A

False - readily isolated on routine culture; further identification based on colony and conidial morphology and PCR and sequencing of ribosomal RNA genes

227
Q

Histopathologic findings with Blastomycosis

A

granulomatous or pyogranulomatous inflammation with intra-lesional budding yeasts; may also have multinucleated giant cells, fibroblasts, and large number of lymphocytes

228
Q

Treatment of choice for Zygomycosis

A

aggressive surgical resection followed by medical therapy with itraconazole for 2-3 months

229
Q

T/F: Candida will grow on blood agar.

A

True - grows on blood agar and Sabouraud’s dextrose agar

230
Q

What genera of fungi have been associated with hyalohyphomycosis?

A

Acremonium, Fusarium, Geotrichum, Paecilomyces, Pseudallescheria, Sagenomella, Scedosporium

231
Q

What type of immunity is required to clear histoplasma capsulatum infection?

A

Th1 immune response – production of IFN-gamma activates macrophages to destroy the fungus

232
Q

Is itraconazole better absorbed in a basic or acidic environment?

A

acidic (it is highly lipophilic and a weak base compound)

233
Q

Why is it not recommended to culture Histoplasma capsulatum?

A

it grows as a mycelium in the laboratory and poses a risk to lab workers

234
Q

What is a geophilic dermatophyte?

A

associated primarily with the decomposition of keratin of hair, feathers, and horn present in soil after the keratinized products have been shed from the host

235
Q

What stain helps to highlight the capsule of Cryptococcus on cytology?

A

India ink

236
Q

Why does Pythium insidiosum stain poorly with periodic acid Schiff stain?

A

lack of chitin in cell wall

237
Q

Major clinical signs of Coccidioidomycosis

A

cough, fever, inappetance, weight loss, tachypnea, lameness, subcutaneous masses or draining skin lesions, lymphadenopathy, neurologic signs, ocular lesions (uveitis, chorioretinitis, endophthalmitis), pericarditis

238
Q

What is the major defense mechanism against Candida spp.?

A

neutrophils and T-cell mediated immunity

239
Q

Histopathologic features of Malassezia dermatitis

A

hyperkeratosis, multifocal parakeratotic hyperkeratosis; characteristic budding, bottle-shaped yeasts and often cocci over an irregular spongiotic epidermal hyperplasia – extends to follicular infundibula (best place to find the yeast organisms)

240
Q

What is the difference between septate or coenocytic micelium?

A

septate micelium - divided into compartments separated by cross walls formed at right angles, each septa has pores and compartment has a single nucleus; Coenocytic mycelium are not compartmentalized

241
Q

Treatment of choice for Lagenidiosis

A

aggressive surgical resection of all infected tissues with wide margins followed by treatment with itraconazole and terbinafine

242
Q

How can different species of Malassezia be identified?

A

DNA sequencing (or mass spectrometry)

243
Q

Most common species of Cryptococcus to infect cats?

A

Cryptococcus gatii

244
Q

Where are the fungi located in a typical ringworm lesion?

A

central portion contains dead fungi, viable fungi at the periphery causes a red ring

245
Q

Treatment of choice for Candidiasis

A

correct underlying disease, keep dry and clean; topical antifungals (nystatin, azoles, amphotericin B, terbinafine) +/- oral antifungals (fluconazole - urine; ketoconazole or itraconazole)

246
Q

T/F: Histoplasmosis is rare in cats.

A

False - cats are as susceptible to histoplasmosis as dogs (second most common systemic fungal infection in cats)

247
Q

What breed(s) of cat(s) are prone to high carriage rates of Malassezia yeasts

A

Devon rex and sphynx cats

248
Q

Why is it not recommended to culture Coccidioides?

A

culture is a health hazard to lab employees

249
Q

Why are there no susceptibility tests currently available for Malassezia?

A

Malassezia pachydermatis does not exhibit sufficient growth in the standard defined (and lipid-free) RPMI 1640 medium to permit the reference method use for susceptibility

250
Q

Why is medical therapy for pythiosis typically unrewarding?

A

ergosterol is generally lacking in the oomycete cell membrane (and ergosterol is the target for most antifungal drugs)

251
Q

What breeds are at increased risk of Malassezia dermatitis?

A

West Highland white terriers, English setters, shih tzus, basset hounds, American cocker spaniels, boxers, dachshunds, poodles, and Australian silky terriers

252
Q

Mode of transmission of Coccidioides?

A

inhalation of arthroconidia from the environment; rarely cutaneous inoculation

253
Q

Causative organism of Sporotrichosis

A

Sporothrix schenckii complex - Sporothrix globosa, S. brasiliensis, S. schenckii, S. albicans, S. luriei

254
Q

Cytological characteristics of Sporotrichosis

A

pyogranulomatous inflammation; cats: large #s of round to cigar-shaped yeasts intracellularly within neutrophils or macrophages and extracellularly; 4-6 um in diameter and can exhibit single bud with a narrow base

255
Q

What stain highlights the hyphae of pythiosis?

A

Gomori’s methenamine silver (GMS) – do NOT stain well with periodic acid Schiff stain

256
Q

DDX for Rhinosporidiosis

A

Nasal neoplasia, cryptococcosis, sinonasal aspergillosis, nasal mites (Pneumonyssoides caninum), foreign bodies

257
Q

T/F: Dogs are at greater risk of blastomycosis compared to humans

A

True - 10X higher risk for dogs

258
Q

Treatment of choice for hyalohyphomycosis

A

Discontinuation of immunosuppressive therapy, systemic antifungals - itraconazole, amphotericin B, voricoanzole, posaconazole

259
Q

T/F: Cats infected with cryptococcus are systemically unwell.

A

False - cryptococcosis is usually a chronic infection in cats and animals are usually otherwise well but may have mild lethargy and inappetance

260
Q

T/F: Absorption of both ketoconazole and itraconazole is enhanced by giving with food.

A

True

261
Q

What are the different types of mycetomas?

A

Actinomycotic mycetomas (Actinomyces spp or Nocardia spp), Dermatophytic mycetomas, Eumycotic mycetomas (non-dermatophyte fungi)

262
Q

What is the first line treatment of Malassezia dermatitis in cats?

A

itraconazole

263
Q

_____ are an interconnected network of hyphae that develops as hyphae grow.

A

Micelium

264
Q

Adverse events reported with griseofulvin?

A

teratogenic, bone marrow suppression (cats)

265
Q

What are the virulence factors of Blastomyces?

A

cell surface glycoprotein = BAD-1 (adhesin that binds to host cell receptors on macrophages); other cell wall compoments such as alpha-1,3-glucan

266
Q

What are the stages of dermatophyte infection?

A

1) Adherence of arthroconidia to corneocytes (2-6 hours afer exposure); 2) Fungal conidial germination and penetration into stratum corneum (4-6, maybe 24 hours); 3) Dermatophyte invasion of keratinized structures (7 days)

267
Q

What is the preferred specimen for culture of Pythium insidiosum?

A

small pieces of fresh, nonmacerated tissue –> cultured on vegetable extract agar supplemented with streptomycin and ampicillin –> mycelial growth observed within 12-24 hours

268
Q

Does phaeohyphomycosis occur more commonly in dogs or cats?

A

cats

269
Q

The blastomyces cell wall antigen test cross reacts with what other organism?

A

histoplasma (false positives may occur when an animal has histoplasmosis)

270
Q

Yeasts with narrow-based budding

A

Sporothrix, Cryptococcus, Candida

271
Q

What are the important traits that distinguish oomycetes from fungi?

A

production of motile, flagellate zoospores that act as infective elements in wet environments; oomycete cell membrane generally lacks ergosterol or chitin - have cellulose and beta-glucan

272
Q

What creates the color change with dermatophytes in DTM?

A

dermatophytes preferentially use the protein in the medium as they begin to grow –> produce alkaline metabolites that cause the medium to turn red

273
Q

When does the color change in a DTM plate occur with saprophytic fungi?

A

Long after appearance of the colonies; saprophytic fungi metabolize the carbohydrates first –> produce acidic metabolites that do not change the color of the medium
After the CHO source has been depleted, saprophytes use the proteins and produce a red color change

274
Q

What is the only saprophytic fungi that produces a red color change in DTM at the same time the colonies appear?

A

Scopulariopsis brevicaulis – tan to light brown, smooth or mealy colony

275
Q

What 4 species of dermatophytes have some strains that fluoresce with the Wood’s lamp?

A

“Distorted CATS” -

  1. Microsporum distortum
  2. Microsporum canis
  3. Microsporum audouinii
  4. Trichophyton schoenleini
276
Q

Gross appearance of Microsporum canis on Sabouraud’s dextrose agar

A
  • Flat
  • Spreading
  • White to cream colored surface
  • Cottony with radial grooves
  • Reverse pigment is golden yellow to brownish yellow
277
Q

Microscopic appearance of Microsporum canis from a fungal culture

A

Macroconidia are spindle-shaped
>6 cells
Thick-walled
Terminal knob

278
Q

Gross appearance of Microsporum gypseum on Sabouraud’s dextrose agar

A
  • Flat
  • Spreading
  • Suede-like to granular
  • Deep cream to twany-buff to pale cinnamon colored red surface
  • Reverse pigment is yellow-brown often with a central darker brown spot
279
Q

Microscopic appearance of Microsporum gypseum from a fungal culture

A

Ellipsoidal, thin-walled
4-6 celled macroconidia

280
Q

What are the most common causes of dermatophytosis in the horse?

A

Trichophyton equinum #1
T. mentagrophytes
T. verrucosum
M. equinum
M. gypseum

281
Q

What are the growth requirements for the most common species of dermatophytes in the horse?

A

Trichophyton equinum - needs niacin added to Sabouraud’s dextrose agar

282
Q

What are the components of Dermatophyte Test Medium

A
  • Sabouraud’s dextrose agar
  • Cycloheximide
  • Gentamicin
  • Chlortetracycline
  • Phenol red
283
Q

What are the components of Enhanced sporulation agar/rapid sporulating media

A
  • Dextrose agar
  • Petones
  • Chloramphenicol
  • Gentamicin
  • Cycloheximide
  • Bromothymol
284
Q

What are the growth requirements for the most common species of dermatophytes in cattle?

A

Trichophyton verrucosum – needs thiamine +/- inositol added to Sabouraud’s dextrose agar

285
Q

What is in PMS Fungal/TZANCK Stain

A

Toluidine blue and basic fuschin in 30% ethyl alcohol

286
Q

Are fungi gram positive or gram negative?

A

gram positive

287
Q

What species of dermatophyte is thought to be the most common in pigs?

A

Nannizzia nana – zoophilic and geophilic

288
Q

Appearance of Nannizzia nana on fungal culture on Sabouraud’s dextrose agar

A
  • flat
  • white to cream colored
  • suede-like to powdery surface
  • brownish-orange reverse pigment
289
Q

Appearance of Nannizzia nana on cytology from fungal cultures

A

Macroconidia are ovoid to pyriform with 1-3 cells

290
Q

Appearance of Trichophyton equinum on fungal culture on Sabouraud’s dextrose agar

A
  • Flat
  • white to cream colored
  • suede to powdery
  • brownish-orange reverse pigment
291
Q

Appearance of Trichophyton equinum on cytology from fungal cultures

A

Abundant microconidia
Rare clavate, smooth, thin-walled macroconidia

292
Q

Appearance of Trichophyton mentagrophytes on fungal culture on Sabouraud’s dextrose agar

A
  • flat
  • white to cream colored
  • powdery to granular surface
  • red-brown submerged peripheral fringe and reverse pigment
293
Q

Appearance of Trichophyton mentagrophytes on cytology from fungal culture

A
  • numerous single-celled microconidia –> often in dense clusters
  • microconidia are hyaline, smooth-walled and are predominantly spherical to subspherical
  • spherical chlamydoconidia
  • spiral hyphae
  • smooth, thin-walled, clavate shaped, muticelled macroconidia
294
Q

Appearance of Trichophyton verrucosum on fungal culture on Sabouraud’s dextrose agar

A
  • glabrous, heaped, folded white colony
  • no reverse color
295
Q

Appearance of Trichophyton verrucosum on cytology from fungal culture

A
  • clavate to pyriform microconidia
  • macroconidia are rare, “rat-tail” or “string-bean” shaped
296
Q

How are dermatophytosis and trichomycosis nodularis different?

A

dermatophytosis - fungal infection of hair shaft (intrafollicular) and stratum corneum
trichomycosis nodularis - fungal infection of hair shaft (extra-follicular)

297
Q
A

Microsporum canis

298
Q
A

Microsporum canis

299
Q
A

Microsporum gypseum

300
Q
A

Microsporum gypseum

301
Q
A

Trichophyton mentagrophytes

302
Q
A

Trichophyton mentagrophytes

303
Q
A

Vet Derm Review (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions