Fungal Flashcards
(143 cards)
1
Q
What is Cryptococcus?
A
A systemic fungal infection affecting various mammals, most commonly cats
2
Q
Where is Cryptococcus considered an emerging pathogen?
A
In areas such as the Pacific Northwest of the U.S.
3
Q
Has zoonotic or direct animal-to-animal transmission of Cryptococcus been reported?
A
No
4
Q
What is the typical starting site of Cryptococcus infection?
A
Upper respiratory tract
5
Q
What are the two forms of Cryptococcus?
A
- Environmental form: Filamentous
- Host form: Encapsulated budding yeast
6
Q
What is the size range of Cryptococcus yeast cells?
A
3.5–7 µm in diameter; capsule up to 20 µm thick
7
Q
What environmental sources are associated with Cryptococcus?
A
- Pigeon droppings (C. neoformans complex)
- Eucalyptus/leaf litter (C. gattii complex)
8
Q
What species complex of Cryptococcus affects immunocompromised humans?
A
C. neoformans species complex
9
Q
What species complex of Cryptococcus affects immunocompetent individuals?
A
C. gattii species complex
10
Q
What are the serotypes of Cryptococcus?
A
- A
- B
- C
- D
- AD hybrid
11
Q
What is a key virulence factor of Cryptococcus?
A
Polysaccharide capsule
12
Q
What are the risk factors for Cryptococcus infection in humans?
A
HIV or other immunocompromised states
13
Q
What are common clinical signs of Cryptococcus in cats?
A
- Chronic sneezing
- Mucopurulent/hemorrhagic nasal discharge
- Nasal bridge swelling/ulcerated lesion
- Cutaneous/subcutaneous nodules
- Ocular signs
- Neurologic signs
14
Q
What are common clinical signs of Cryptococcus in dogs?
A
- Lethargy
- Weight loss
- Neurologic signs
- Nasal discharge
- Cutaneous lesions
- Lymphadenopathy
- GI signs
15
Q
What is the typical latency period for Cryptococcus infection?
A
2 months to 1 year
16
Q
What is the gold standard for diagnosing Cryptococcus?
A
Visualization of encapsulated budding yeast
17
Q
What does the CALAS test detect?
A
Polysaccharide capsule antigen
18
Q
What is the sensitivity of the CALAS test in cats?
A
95–100%
19
Q
What is the treatment strategy for Cryptococcus?
A
- Induction Phase: Amphotericin B ± 5-flucytosine or fluconazole
- Maintenance Phase: Azole monotherapy
20
Q
What is the recommended treatment duration for cats with Cryptococcus?
A
2–12 months (median ~4 months)
21
Q
What is the overall success rate for treating Cryptococcus in cats?
A
~75%
22
Q
What is a common false positive cause for serologic testing in cats?
A
Subclinical nasal colonization
23
Q
What are the key imaging findings in dogs with pulmonary cryptococcosis?
A
- Interstitial to alveolar patterns
- Nodular infiltrates
- Pleural effusion
24
Q
True or False: Cryptococcus can cause CNS involvement in both cats and dogs.
A
True
25
What is a potential concern when collecting CSF for Cryptococcus diagnosis?
Increased ICP and decompensation
26
What are the possible complications related to the treatment of Cryptococcus?
* Inflammatory response to fungal die-off
* Neurologic worsening in the first 4 days
27
Fill in the blank: Cryptococcus is most commonly found in _______.
pigeon droppings
28
What is the significance of maintaining the same lab for CALAS titers during treatment?
For consistency in results
29
What is the etiologic agent of Coccidioidomycosis?
Soil-borne dimorphic fungi of the genus Coccidioides
## Footnote
Coccidioidomycosis is a systemic fungal infection caused by these fungi.
30
What are arthroconidia?
Barrel-shaped spores that fragment from the hyphae of Coccidioides
## Footnote
Arthroconidia persist in soil and become aerosolized during soil disruption.
31
What happens after arthroconidia are inhaled?
They are phagocytosed by alveolar macrophages and transform into spherules
## Footnote
Each spherule matures to release hundreds of endospores.
32
In which regions is Coccidioides species endemic?
Semi-arid to arid regions at low elevations with hot summers
## Footnote
Endemic areas include Southwestern and Western USA, parts of Mexico, and Central and South America.
33
Which Coccidioides species are primarily found in California and New Mexico?
C. immitis
## Footnote
C. posadasii is found in New Mexico and widely elsewhere.
34
What are some risk factors for Coccidioidomycosis in dogs?
* Outdoor housing during the day
* Roaming over >1 acre of land
* Frequenting desert terrain
* Digging behaviors
* Travel/residence in endemic regions
## Footnote
Digging behaviors increase risk 6.7-fold.
35
What are common clinical signs of Coccidioidomycosis in dogs?
* Intermittent low-grade fever
* Lethargy
* Inappetence
* Weight loss
* Respiratory signs (harsh cough, tachypnea)
## Footnote
Dissemination signs include lameness, skin lesions, and neurologic signs.
36
What is the typical diagnostic approach for Coccidioidomycosis?
Based on clinical suspicion and diagnostics including:
* Cytology of aspirates or fluids
* Serology for antibodies
* Histopathology, biopsy, or fungal culture
## Footnote
Cytology typically detects spherules.
37
What are some laboratory findings in dogs with Coccidioidomycosis?
* Mild non-regenerative anemia
* Mild neutrophilia
* Hypoalbuminemia
* Hyperglobulinemia (~50%)
* Proteinuria (~60%)
## Footnote
Proteinuria is associated with immune complex glomerulonephritis.
38
What imaging findings are associated with Coccidioidomycosis?
* Hilar lymphadenopathy
* Mild/moderate interstitial infiltrates
* Possible alveolar or bronchointerstitial infiltrates
## Footnote
Thoracic radiographs may show these findings.
39
What is the recommended first-line antifungal medication for pulmonary Coccidioidomycosis?
Fluconazole
## Footnote
It has good CNS penetration.
40
What is the required treatment duration for Coccidioidomycosis?
At least 6 months, often 12+ months
## Footnote
Some dogs may require lifelong therapy.
41
What are high-risk human groups for Coccidioidomycosis?
* Construction and agricultural workers
* People with HIV/AIDS
* African-Americans and Filipinos
* Pregnant women in third trimester
## Footnote
Estimated human dissemination rate is ~0.5% of infected individuals.
42
True or False: Dogs can transmit Coccidioidomycosis directly to humans.
False
## Footnote
Direct transmission from dogs to humans has not been reported.
43
Fill in the blank: The hallmark of Coccidioidomycosis infection is the presence of _______.
spherules
## Footnote
Spherules are typically visible in cytologic evaluations.
44
What is the sensitivity of a urine cryptococcal antigen test for detecting Coccidioides?
<20%
## Footnote
This test is not recommended for Coccidioides detection.
45
What are some associated ocular signs of Coccidioidomycosis in dogs?
* Uveitis
* Chorioretinitis
* Endophthalmitis
## Footnote
These signs indicate possible dissemination of the infection.
46
What is the primary causative agent of Blastomycosis?
Blastomyces dermatitidis
## Footnote
Additionally, Blastomyces gilchristii can also cause the infection, while atypical cases may involve Blastomyces helicus.
47
What is the primary causative agent of Histoplasmosis?
Histoplasma capsulatum
## Footnote
Histoplasma has been reclassified into at least five phylogenetic species globally.
48
What are the two major cryptic species of Histoplasma identified in the U.S.?
* Histoplasma mississippiense
* Histoplasma ohiense
49
What type of fungi are Blastomyces and Histoplasma?
Thermodimorphic fungi
50
How do Blastomyces and Histoplasma exist in the environment?
As saprophytic molds in the environment at temperatures less than 30°C
## Footnote
They convert to pathogenic yeast forms in host tissue at temperatures greater than 30°C.
51
How do Blastomycosis and Histoplasmosis infections occur?
Through inhalation of aerosolized spores
52
What environmental conditions favor the growth of Blastomyces?
Moist, acidic, sandy soil rich in decaying vegetation, near waterways
53
What environmental conditions favor the growth of Histoplasma?
Nitrogen-rich soil contaminated with bird or bat droppings
54
Where is Blastomycosis endemic in the United States?
Eastern North America, particularly in the Great Lakes and St. Lawrence River regions
55
Where is Histoplasmosis endemic in the United States?
Throughout the Midwest, South, and Southeast
56
Which species is more commonly affected by Blastomycosis?
Dogs
57
Which species is more commonly affected by Histoplasmosis?
Cats
58
What age group is typically affected by Blastomycosis in dogs?
2–5 years
59
What is the mean age for cats affected by Histoplasmosis?
7 years
60
What lifestyle factor increases the risk of Blastomycosis in dogs?
Outdoor exposure near endemic areas
61
What immune response is involved in protective immunity against Blastomyces and Histoplasma?
* Innate immune recognition via mannose and β-glucan receptors
* Adaptive Th1/Th17 response
62
What are common clinical signs of Blastomycosis?
* Lethargy
* Fever
* Anorexia
* Weight loss
* Respiratory signs
63
What are common clinical signs of Histoplasmosis?
* Lethargy
* Fever
* Anorexia
* Weight loss
* Respiratory signs
64
What percentage of dogs with Histoplasmosis show gastrointestinal involvement?
~50%
65
What laboratory finding is common in both infections?
Peripheral lymphadenopathy
66
What is a common hematological finding in dogs and cats with these fungal infections?
Anemia (often non-regenerative)
67
What imaging technique is used to assess Blastomycosis in the thoracic region?
Thoracic Radiography
68
What is the best specimen type for diagnosing Blastomycosis?
Peripheral lymph node aspirates
69
What is the preferred first-line treatment for mild to moderate Blastomycosis and Histoplasmosis?
Itraconazole
70
What are the adverse effects of Itraconazole?
* Hepatotoxicity
* Ulcerative skin lesions
71
What test has high sensitivity for detecting Blastomyces and Histoplasma antigens?
Urine Antigen Testing
72
What is a limitation of fungal culture for diagnosing these infections?
Slow results (up to 30 days) and low sensitivity
73
What diagnostic imaging finding may mimic infiltrative neoplasia in abdominal ultrasound for Histoplasmosis?
Hepatomegaly with altered echogenicity
74
What is the sensitivity of the Blastomycosis Antigen EIA test in dogs using urine samples?
93%
75
What is the treatment dosage for Fluconazole in dogs and cats?
20 mg/kg PO SID
76
What is the recommended dosage of PO for cats in resistant or relapsing infections?
15 mg/kg once, then 7.5 mg/kg PO SID
## Footnote
Used as salvage therapy in resistant or relapsing infections
77
What is the dosage of Voriconazole for dogs?
5 mg/kg PO q12h
78
What is the dosage of Voriconazole for cats?
12.5 mg total dose q72h (not per kg)
79
What is the use of Amphotericin B in severe or life-threatening disease?
1–2 mg/kg IV on Mon/Wed/Fri for dogs; 0.5–1 mg/kg IV on Mon/Wed/Fri for cats
80
What is the preferred formulation of Amphotericin B?
Lipid/liposomal (less nephrotoxic)
81
What is the maximum cumulative dose of Amphotericin B for dogs?
≤24 mg/kg
82
What is the maximum cumulative dose of Amphotericin B for cats?
≤12 mg/kg
83
What are the indications for glucocorticoids in treatment?
Severe ocular, CNS, or respiratory involvement
84
What is the dosing range for Prednisolone?
0.25–1 mg/kg/day
85
What is the minimum treatment duration for blastomycosis?
6 months
86
What is a common complication that may occur at the start of treatment?
Initial worsening of clinical signs due to inflammatory response
87
What is the relapse rate for dogs treated for blastomycosis?
Approximately 20%
88
What is the relapse rate for cats and dogs treated for histoplasmosis?
20–40%
89
What are the criteria for safe discontinuation of antifungal therapy?
Minimum of six months of continuous antifungal treatment; at least one month beyond resolution of clinical signs and abnormalities
90
What is the urine antigen concentration threshold for dogs to consider discontinuation?
≤0.4 ng/mL on two consecutive rechecks
91
How often should physical examinations be conducted during treatment?
Every 1–3 months
92
What does a rising urine antigen concentration suggest?
Progression or relapse
93
What is the reported survival rate at hospital discharge?
87–90%
94
What negative prognostic indicator is common for both diseases?
CNS involvement
95
What urine antigen level at diagnosis in dogs with blastomycosis indicates 100% survival at 6 months?
< 5 ng/mL
96
What urine antigen level in dogs with blastomycosis indicates 59% survival at 6 months?
≥ 5 ng/mL
97
What is the recommendation for discontinuation of antifungal therapy in cats?
Continue until antigen is no longer detectable in urine
98
What is the maximum treatment duration for disseminated disease?
>1 year
99
What type of feeding tube may aid nutritional support and medication administration?
Esophagostomy or gastrostomy feeding tube
100
What is the genus of fungi that includes approximately 450 species and is divided into subgenera, sections, and series?
Aspergillus
## Footnote
Aspergillus is taxonomically divided into six subgenera, 27 sections, and 87 series.
101
What type of fungi are Aspergillus species?
Aerobic, saprophytic fungi
## Footnote
These fungi thrive in decaying organic matter.
102
What is the most common form of disease caused by Aspergillus in dogs and cats?
Fungal rhinosinusitis
## Footnote
Typically non-invasive and restricted to the nasal cavity and paranasal sinuses.
103
Which species is the most common causative agent of Sinonasal Aspergillosis in dogs?
Aspergillus fumigatus
## Footnote
It belongs to the subgenus Fumigati.
104
What is the median age at diagnosis for dogs with Sinonasal Aspergillosis?
5–7 years
## Footnote
Any age is possible.
105
Which breeds of dogs are overrepresented in cases of Sinonasal Aspergillosis?
* Golden Retrievers
* Labrador Retrievers
* German Shepherds
* Belgian Shepherds
* Rottweilers
* Malamutes
* Rough/Border Collies
* Bull Terriers
* Staffordshire Terriers
* Miniature Schnauzers
## Footnote
Dolichocephalic large breeds are particularly at risk.
106
What are the common breeds of cats affected by Sinoorbital Aspergillosis?
* Persians
* Himalayans
* Exotics
* Scottish Shorthairs
* British Shorthairs
* Ragdolls
## Footnote
Brachycephalic purebreds are more susceptible.
107
What risk factor may be associated with Sinoorbital Aspergillosis in cats?
Diabetes mellitus
## Footnote
FIV and FeLV are usually negative.
108
What describes the initial infection process of Aspergillus in the sinonasal cavity?
Inhaled conidia germinate, forming hyphal plaques
## Footnote
This occurs in areas of optimal temperature and humidity.
109
True or False: In dogs and most cats, the infection caused by Aspergillus is typically invasive.
False
## Footnote
The infection is usually non-invasive, with hyphae remaining superficial.
110
Which immune cells recognize pathogen-associated molecular patterns (PAMPs) on Aspergillus?
Dendritic cells and pattern recognition receptors (PRRs)
## Footnote
C-type lectin receptors and Toll-like receptors are examples of PRRs.
111
In dogs with Sinonasal Aspergillosis, what type of immune response is predominantly observed?
Th1 responses with upregulated IL-10
## Footnote
IL-10 may limit tissue damage but impair fungal clearance.
112
What are the typical findings on CT for Sinonasal Aspergillosis?
* Cavitated lysis of nasal turbinates
* Soft tissue opacity in nasal cavity or sinuses
* Mucosal thickening
* Lysis of the cribriform plate, palatine, orbital, or frontal bones
* Lymphadenopathy
## Footnote
These findings help in diagnosing the condition.
113
What is the gold standard for monitoring treatment response in Sinonasal Aspergillosis?
Repeat endoscopic examination
## Footnote
Recommended 2–4 weeks after treatment.
114
What is the mechanism of action for azole antifungals used in treatment?
Inhibition of 14-α-demethylase
## Footnote
This enzyme is essential for ergosterol synthesis, disrupting fungal cell membranes.
115
What is the recurrence rate for Sinonasal Aspergillosis post-treatment with 1–2% enilconazole?
11%
## Footnote
Recurrence can occur 2–36 months post-treatment.
116
What is the prognosis for feline Sinoorbital Aspergillosis?
Guarded to poor
## Footnote
Prolonged systemic antifungal therapy for ≥6 months is required.
117
Which antifungal is considered the empiric drug of choice for systemic therapy in cats?
Posaconazole
## Footnote
It is well tolerated and has rare hepatotoxicity.
118
What is the effect of ital debridement and enucleation on outcomes?
Do not improve outcomes
## Footnote
This indicates that these procedures are not beneficial in improving patient outcomes.
119
Which Aspergillus species are resistant to standard antifungals?
Many cryptic Aspergillus species
## Footnote
These species are intrinsically resistant, making treatment challenging.
120
What is recommended for antifungal susceptibility?
Antifungal susceptibility testing is recommended
## Footnote
This testing helps determine the effectiveness of antifungal drugs against specific strains.
121
What is the empiric drug of choice for systemic therapy in cats?
Posaconazole
## Footnote
Posaconazole is well tolerated and has rare hepatotoxicity.
122
Which drug is often combined with posaconazole in systemic therapy for cats?
Terbinafine
## Footnote
This combination is used to enhance antifungal efficacy.
123
Why is itraconazole not recommended for systemic therapy in cats?
High MICs for A. felis
## Footnote
This means that itraconazole is less effective against this specific species.
124
What should be avoided due to severe adverse effects in systemic therapy?
Voriconazole
## Footnote
Adverse effects include blindness, paraplegia, and anorexia.
125
When is Amphotericin B considered effective?
In combination with posaconazole ± terbinafine
## Footnote
Not recommended for empiric use due to MIC variability.
126
What type of drug is Caspofungin?
An echinocandin
## Footnote
Echinocandins inhibit β-1,3-D-glucan synthesis.
127
What is advisable to ensure MICs are achieved when using posaconazole?
Therapeutic drug monitoring of posaconazole levels
## Footnote
This monitoring helps to maintain effective drug concentrations.
128
What are disseminated opportunistic fungal infections in dogs often caused by?
Aspergillus, Penicillium, Rasamsonia, Paecilomyces, Scopulariopsis
## Footnote
These infections are uncommon and considered rare in cats, often severe and challenging to treat.
129
Which phyla do most medically relevant fungi belong to?
Ascomycota, Basidiomycota
## Footnote
Ascomycota includes Aspergillus, Candida, and dimorphic fungi like Histoplasma, Blastomyces, and Coccidioides.
130
What is the most common cause of disseminated invasive aspergillosis?
Aspergillus deflectus, A. terreus, A. fumigatus, A. niger
## Footnote
These differ from sinonasal or sino-orbital forms where A. fumigatus and A. felis predominate.
131
What are common sites affected by disseminated invasive aspergillosis?
* Brain
* Eyes
* Vertebrae
* Intervertebral discs
* Kidneys
* Liver
* Spleen
* Lymph nodes
* Lungs
* Long bones
* Pancreas
## Footnote
These sites are frequently involved in cases of disseminated invasive aspergillosis.
132
What are the primary routes of infection for disseminated invasive aspergillosis?
Inhalation of conidia, cutaneous routes, gastrointestinal routes
## Footnote
Inhalation is the most common route.
133
What traits contribute to the virulence of aspergillus pathogens?
* Thermotolerance (survival at >37°C)
* Tissue invasion via lipase and phospholipase secretion
* Immune evasion and use of host tissue as a nutrient source
## Footnote
These traits help aspergillus species thrive in host environments.
134
Which dog breeds are predisposed to disseminated invasive aspergillosis?
German Shepherd Dogs, Rhodesian Ridgebacks
## Footnote
These breeds have suspected immunodeficiencies increasing their risk.
135
What immune response is induced by the recognition of aspergillus?
Th1 response (↑ IL-12, IL-18, TNF-α, IFN-γ)
## Footnote
Th2-dominant responses are associated with progressive disease.
136
What are some clinical signs of disseminated invasive aspergillosis in dogs?
* Lethargy
* Anorexia
* Polyuria/polydipsia (renal)
* Altered mentation (neurologic)
* Cough (respiratory)
* Uveitis (ophthalmic)
## Footnote
Signs vary depending on the affected organ system.
137
What are common CBC findings in dogs with disseminated invasive aspergillosis?
* Neutrophilia
* Normocytic, normochromic, nonregenerative anemia
* Monocytosis (in some)
## Footnote
These findings help in the diagnosis process.
138
What is the gold standard for diagnosing disseminated invasive aspergillosis?
Isolation of a fungal pathogen from a normally sterile site
## Footnote
This can be achieved through fungal culture and cytologic/histopathologic identification.
139
How is the Galactomannan Antigen EIA used in diagnosis?
Detects galactomannan in urine and serum
## Footnote
Sensitivity is ~92% in serum and specificity is ~93% for disseminated invasive aspergillosis.
140
What are the microscopic features of Aspergillus hyphae?
Thin-walled, septate, branching, ~5 μm diameter
## Footnote
These features are critical for identification in cytology and histopathology.
141
What is the prognosis for dogs diagnosed with disseminated invasive aspergillosis?
Grave in most cases due to delayed diagnosis, extensive dissemination, concurrent immunosuppression
## Footnote
Approximately 66% of dogs were euthanized within one week of diagnosis.
142
True or False: Disseminated Aspergillus infections in dogs are zoonotic.
False
## Footnote
Dogs do not shed infectious spores.
143
Fill in the blank: Disseminated invasive aspergillosis is primarily treated with _______.
Systemic antifungals (e.g., Posaconazole, Voriconazole, Itraconazole)
## Footnote
Susceptibility testing can guide the choice of antifungal therapy.
