Infectious Dz - Fungal Flashcards
Where is blastomycosis distributed?
On the eastern half of the US, especially in the Mississippi, Ohio, and Saint-Lawrence River values
What type of fungi is Blastomyces dermatitidis?
Dimorphic
In what form is Blastomyces dermatitidis in the host?
yeast
In what form does Blastomyces dermatitidis exist in the soil as?
a fungal hyphae
What form of Blastomyces dermatitidis is infective?
only the fungal form
By what route does Blastomyces dermatitidis infection occur?
Inhalation (most common) and direct inoculation
What is the incubation time of Blastomyces dermatitidis?
Long incubation - 1-3 months
Where does Blastomyces dermatitidis propagate and how does it get there?
Via hematogenous spread it propagates to the skin, eyes, lymph nodes, bone, and CNS
What is the ‘poster dog’ for blastomycosis?
Young (2-4 years) and large hunting breeds
What are the risk factors for blastomycosis in dogs?
living near water and proximity to excavated or disturbed soil
Is blastomycosis found in cats?
It is very rare
What are the PE findings associated with blastomycosis?
Non-specific signs of fever, anorexia, and weight loss Respiratory signs are common Ocular manifestations - uveitis Granulomas Draining lesions Lameness
What will you find on CBC in a patient with blastomycosis? Chemistry?
CBC - inflammatory leukogram
Chemistry (from most to least common)- Low albumin, high globulin, and hypercalcemia
What will you find on cytology in patients with blastomycosis?
Broad-based budding yeast and pyogranulomatous inflammation with concurrent presence of neutrophils with activated macrophages, lymphocytes, and plasma cels
What will you see on rads in a patient with Blastomycosis?
Variable lung pattern - classically diffuse miliary to nodular
Tracheobronchial enlargement in 25% of cases
Osteolysis with periosteal reaction in bones
What does serology detect for in a suspected Blasto case?
antibodies
What is the gold standard diagnostic test for blastomycosis?
Galactomannan cell wall test
What is the Galactomannan cell wall test?
It is an antigen test with very high sensitivity. Urine is more sensitive than serum
There is some cross-reactivity with Histoplasma so a cytology will need to be done to confirm
What diagnostic test is not recommended for blastomycosis?
Culture - because it reverts to the fungal form and there is a potential danger for lab personnel
How is blastomycosis treated?
Triazoles - Itraconazole is the drug of choice but Fluconazole may have similar efficacy and Fluconazole and voriconazole achieve better CNS/ocular penetration than itraconazole
Amphotericin B may be warranted in more aggressive/extensive disease
Glucocorticoids for decreasing pulmonary inflammation associated with the fungal die off - avoid high doses
When is surgery indicate to treat blastomycosis?
If there is severe panuveitis that requires enucleation
Is blastomycosis treatment long or short term? When do you know when to stop treatment?
Long term
Use Galactomannan assay results to determine presence of fungi
What is the prognosis of blastomycosis?
Variable cure rates - 50-75%
Relapses are common within 2 years
What are the negative prognostic factors of blastomycosis?
CNS involvement, severity of lung disease, and high band count on CBC
What are the differentials to be considered with blastomycosis?
Neoplasia, other systemic mycoses, and systemic protozoal infections
Where is histoplasmosis distributed?
Similar to blasto - north of the equator and in the eastern US in the Ohio and Mississippi river valleys
What causes histoplasmosis?
Histoplasma capsulatum
What type of fungus is histoplasmosis?
Dimorphic
How does histoplasmosis infection occur?
It is inhaled or ingested by the host from avian and/or bat guano
Where does Histoplasma capsulatum replicate/dissemiate?
In macrophages
What age of dogs does histoplasmosis commonly occur in?
young patients (median age is 3 years)
What physical/clinical findings are associated with histoplasmosis in dogs?
GI signs are seen in 50-60% of cases, respiratory signs in 10% of cases, and can have ocular, skin, and CNS signs
How does histoplasmosis present in cats?
Often non-specific signs - respiratory (40%), ocular manifestations, lymphadenopathy, skin involvement, bone marrow involvement
What disease is co-infected with histoplasmosis in cats in 28% of cases?
FeLV
How is histoplasmosis diagnosed?
minimum database, imaging, cytology, and galactomannan test
What will you find on CBC in patients with histoplasmosis? Chemistry?
CBC - non-regenerative anemia +/- other cytopenias, high/low WBC counts
Chemistry - increased liver values, low albumin, high globulin
How does histoplasmosis look on thoracic rads?
Classic diffuse interstitial miliary to nodular pattern
Tracheobronchial lymphadenopathy
How does histoplasmosis look on abdominal rads?
Hepato/splenomegaly
Thickened intestinal wall with disruption of layering
How will the skeletal system look on radiographs in patients with histoplasmosis?
osteolysis with periosteal reaction
How can you get samples for cytology in histoplasmosis cases?
Impression smears, fine needles aspirates, lung washes, and rectal scraping
What will histoplasmosis look like on cytology?
Granulomatous/pyogranulomatous inflammation
Can you find Histoplasma in blood?
yes - in 20% of dogs and cats
Is serology recommended for diagnosis of histoplasmosis?
No - it has poor sensitivity/specificity
How is histoplasmosis treated?
Azoles - Itraconazole is the azole of choice
In severe disseminated cases - Amphotericin B
Glucocorticoids - to decrease pulmonary inflammatory reaction associated with fungal die off
What is the prognosis of histoplasmosis?
Good to poor prognosis based on the location
What are the positive prognostic factors for histoplasmosis?
presence of diarrhea
What are the negative prognostic factors for histoplasmosis?
need for oxygen supplementation, icterus, and abdominal organomegaly
Is histoplasmosis treatment short or long term? When do you know when to stop therapy?
Long term - 6-12 months
End based on clinical signs, resolution of radiographic signs, and negative urine galactomannan antigen test
What are the differentials for histoplasmosis?
Other systemic mycoses, IBD, and cancer
Where is Coccidioidomycosis?
Coccidioides immitis is distributed on the Southwestern US
Coccidioides posadasii is in South America, Mexico, and part of the west coast
What type of fungi is Coccidioides?
a dimorphic
What does Coccidioides exist as in the environment?
a mycelium
How does Coccidioides infection occur?
Inhalation of Arthroconidia
What form is Coccidioides in the host?
spherules
What is the typical signalment of coccidioidomycosis in the dog?
Younger, active large breed dogs
What are the risk factors for coccidioidomycosis?
Being housed outdoors, walks in the desert, roaming large areas, and living in an endemic area
What is the most common systemic signs in patients with coccidioidomycosis?
fever
What other physical and clinical findings are associated with coccidioidomycosis?
Respiratory signs, bone involvement, CNS, skin, and repro involvement
Pericardial effusion and right sided heart failure
How is coccidioidomycosis diagnosed?
Cytology or serology
How do you acquire samples for a coccidioidomycosis cytology?
FNA, lung wash, pericardial fluid
What will you see on cytology in a patient with coccidioidomycosis?
Pyogranulomatous inflammation
What is the specificity and sensitivity of serology for coccidioidomycosis diagnosis?
Specific but not very sensitive
How is coccidioidomycosis treated medically?
Azoles - fluconazole or itraconazole
In refractory/severe cases - Amphotericin B, Posaconazole or Voriconazole
How is coccidioidomycosis treated surgically?
Limb amputation, enucleation, and pericardectomy
What is the prognosis for coccidioidomycosis?
Guarded to good
Is treatment for coccidioidomycosis short or long term? When do you know when to stop?
long term - > 6 months
Length of therapy is based on resolution of lesions and serology of less than 1:2
What are the prognostic factors for coccidioidomycosis?
CNS involvement is associated with worse prognosis
What are the differentials for coccidioidomycosis?
Other systemic mycoses, IBD, and cancer
What type of fungi is Cryptococcus?
dimorphic
What are the two main species that cause cryptococcus?
C. neoformans and C. gattii
Who does C. neoformans infect?
immunocompromised dogs and people
Who does C. gatti infect?
immunocompetent animals - mostly cats and humans
Where is Cryptococcus distributed?
worldwide - more common on the west coast
True or False: Cryptococcosis is the second most common systemic mycoses found in cats
False - it is the MOST common
What age cats typically get Cryptococcosis?
young age - 4-6 years
What is infection of Cryptococcus assocaited with?
Plant material (C. gattii) or pigeon guano (C. neoformans)
How do cats become infected with Cryptococcus?
Mainly by inhalation of organisms
Can also occur by direct inoculation
How does Cryptococcus spread?
Hematogenous spread - CNS, eyes, skin, lymph nodes, and the abdomen
Local - Bone, brain, and eyes
How do cats with Cryptococcosis present?
Respiratory (upper is more common) - sneezing, stertor, and discharge
CNS - altered mentation, CN deficits, and seizures
Ocular - unresponsive pupils, retinal hemorrhage/detachment, and Chorioretinitis/optic neuritis
Bone - osteomyelitis and facial swelling (ROMAN NOSE)
Subcutaneous masses
What is the signalment for a dog with Cryptococcosis?
Young/middle aged, active large breed dogs
What is the main difference between Cryptococcosis in dogs vs cats?
Dogs are more likely to have systemic signs such as weight loss, fever, and inappetance
What is the most common finding in dogs with Cryptococcosis?
Neurologic signs
How is Cryptococcosis diagnosed?
minimum database, imaging, cytology, culture, and serology
Where do you get samples for cytology in patients with Cryptococcosis?
Exudate, CSF, and aspirates
What will you find on cytology in patients with Cryptococcosis?
Thick-walled organisms - polysaccharide capsule and narrow-based budding
What can you get samples from for culture of Cryptococcosis?
Tissue, urine, CSF, and blood
What are the benefits to culturing for Cryptococcosis?
It grows as a yeast so it is safer for personnel, allows for species ID, and you can determine antifungal sensitivity
What antigen detection test is done for diagnosis of Cryptococcosis?
Latex agglutination test
What does the Latex agglutination test test for?
capsular antigen with serum or cerebrospinal fluid
What is the sensitivity and specificity for the latex agglutination test?
It is very sensitive and specific
When are Latex agglutination false negatives common?
Dogs and patients with localized disease
How is Cryptococcosis treated?
Fluconazole and Amphotericin B + 5-flucytosine
Is the length of treatment for Cryptococcosis long or short? How do you know when to stop treatment?
Treatment is long term - 2-12 months
Treatment is ceased based on resolution of lesions and antigen titers
When should surgery be considered in Cryptococcosis cases?
IF there are large granulomas present
What is the prognosis for Cryptococcosis in cats?
Generally good (60-75% cure rate)
What forms of Cryptococcosis in cats have a poorer prognosis?
CNS cases
What is the prognosis for Cryptococcosis in dogs?
It is more guarded given underlying dysfunction
30-50% success rate
What are the most common clinical signs of Cryptococcosis in cats?
Ulcerative cutaneous lesions and uveitis chorioretinitis
What differentials should be considered for Cryptococcosis?
Other systemic mycoses - i.e. sporotrichosis
What is the etiologic agent of disseminated aspergillosis?
Aspergillus terreus
Who is at risk to develop disseminated aspergillosis?
German shepherds, females, and young/middle age dogs
How does Aspergillosis infection occur?
inhalation of conida
Is Aspergillosus dimorphic?
no - it produces hyphae not yeast
What organs are affected by disseminated aspergillosis?
Bones, spleen, lymph nodes, and kidneys
How do patients with disseminated aspergillosis often present?
Lethargy, lameness, and ataxia
How is disseminated aspergillosis diagnosed?
Minimum database, imaging, fungal culture, cytology, and ELISA
What will you find on minimum database in disseminated aspergillosis patients?
CBC - anemia with leukocytosis
Chemistry - Low albumin/high globulin, azotemia
UA - hyphae occasionally found
What will you find in patients with disseminated aspergillosis on imaging?
Osteolytic lesions, diskospondilitis, and lymph node enlargement
What is the positive incidence rate of urine culture? Blood or CSF culture?
Urine - >50%
Blood or CSF - 30%
Where should you get samples for cytology for disseminated aspergillosis?
urine, aspirates, and airway washes
Is serology dependable for disseminated aspergillosis diagnosis?
No - it is not useful
What test is very good for disseminated aspergillosis infection?
Aspergillus galactomannan antigen ELISA - serum or urine
How is disseminated aspergillosis treated?
Azoles - fluconazole resistance, possible response with posaconazole
Combination therapy is often necessary - Amphotericin B and Terbinafine
What is the prognosis for disseminated aspergillosis?
Poor diagnosis due to systemic immune dysfunction
Survival is less than 40% 1 week post-diagnosis
What are the differentials for disseminated aspergillosis?
other deep mycoses and neoplasia
