Mycology Part 2 Flashcards
1
Q
What is Coccidioidomycosis?
A
- Caused by: Coccidioides immitis
- C. posadasii - in TX, NM, AZ
- Causes disease in animals and humans that can be inapparent to disseminated and fatal
- Marked variation in susceptibility between animals
2
Q
What is the geographic distribution of Coccidioidomycosis?
A
- Endemic areas in the US
- Southwest: CA (San Jaoquin valley, southern desert counties) Neveda, Utah, AZ, NM, TX
- Cases reported in other states too
- Outside US
3
Q
What are the characteristics of Coccidioides immitis?
A
- a dimorphic fungus
- Grows in the mycelial phase in culture and soil
- Grows in the yeast phase in the tissue of an infected animal
- has not yet been grown in the yeast phase in culture
4
Q
What is the prevalence of Coccidioidomycosis?
A
- Most individuals living in endemic areas are exposed to the agent
5
Q
What is the pathogenesis of Coccidioidomycosis?
A
- Inhalation of arthrospores which are formed in soil causes primarily a pulmonary disease
- Dogs sniffing at rodent burrows
- Wind and dust storms
- Adhesins, urease, chitinase
- Granulomas (may resemble tuberculosis) form in the pulmonary tissue and adjacent lymph nodes
- May disseminate to liver, spleen, kidneys, and bones
- Sub-cutaneous abscesses may develop with draining sinus tracts in rare cases
- Yeast-like organism in tissues
- Spherules - 10-80 microns, some up to 200 microns
- Spherules contain few to several hundred endospores - 2-5 microns in diameter (RBC)
- mature spherules rupture and release endospores, which infect adjacent tissues or spread to other body parts
6
Q
What are the clinical manifestation of Coccidioidomycosis?
A
- Severe disease
- dogs, humans, primates
- In cattle, swine, sheep, horses and cats, localized in the thoracic lymph nodes and/or lungs
7
Q
What are the clinical manifestations of Coccidioidomycosis in dogs?
A
- Primarily respiratory problems due to inhalation of spores (tracking and digging/sniffing rodents burrows)
- Listlessness, poor appetite, intermittent diarrhea, cough, weight loss, lameness, enlarged joints, skin lesions
8
Q
How is Coccidioidomycosis clinically diagnosed?
A
- X-ray
- Clinical signs
- Demonstration of the agent
- Serology - Precipitation test
- Intradermal Sensitivity Test - CMI - Coccidioidin
- Fluorescent Antibody test on tissue biopsy
9
Q
How is Coccidioidomycosis Diagnosed in the Laboratory?
A
- Direct examination
- spherules in wet mounts of urine, exudates, pleural or peritoneal fluids
- Cultural examination
- DTM, Sabouraud, and Mycobiotic
- Only grows in mycelial phase in culture
- Fluffy white mycelium in 2-4 weeks
-
Arthrospores (alternating and barrel-shaped) become airborne very easily
- Formalize culture before doing tease mount
- attempt culture only in a safety glove box
10
Q
What is the Epidemiology of Coccidioidomycosis?
A
- Survive in hot weather with little or no rainfall
- Windy weather and blowing dust spreads with spores
11
Q
What is the treatment for Coccidioidomycosis?
A
- Ketoconazole, Fluconazole, and triazole
- Amphotericin B
- Very toxic, monitor kidney function closely
- No vaccine
12
Q
What is Histoplasmosis?
A
- Caused by: Histoplasma capsulatum
- Primarily in pulmonary tissue or intestinal tract
- disseminated form involves spleen and liver
- Yeast cells in circulating monocytes and neutrophils
- Dogs are more susceptible than other animals
13
Q
What are the general characteristics of Histoplasma capsulatum?
A
- Dimorphic fungus
- At 25C and in the environment in the mycelial phase
- At 37C and in the animal body, the yeast phase
14
Q
What is the Geographic Distribution of Histoplasmosis?
A
- Worldwide
- Very prevalent in OH, MS, MI river valleys
- Endemic in Southeast Kansas
15
Q
What is the prevalence of Histoplasmosis?
A
- Is the most frequently diagnosed systemic fungal disease
- Many in endemic areas are infected and sensitized
- few contract disease
16
Q
What is the Pathogenesis of Histoplasmosis?
A
- Inhalation of spores (Conidia)
- Development of granulomas in the lungs
- spread to other tissues of the body
- Enlarged spleen, lymph nodes, and liver
- Monocytes and neutrophils are infected
- Adhesins for adherence to host cells
19
Q
How is Histoplasmosis diagnosed in the laboratory?
A
- Direct examination
- Look for yeast cells in biopsy material
- Look for yeast cells in feces
- Tissue impression smears of liver, spleen, lung
- Culture:
- On Mycobiotic
- At 25C Mycelial phase
- at 37C Yeast phase
- Blood sample or buffy coat
- Tease Mount only after formalizing the culture
- Conidia with cocklebur appearance - in the mycelial phase
- On Mycobiotic
26
Q
What are the Clinical Manifestation of Blastomycosis?
A
- Eye lesions
- Enlarged Thoracic lymph nodes
- lymphadenopathy
- Bone and skin lesions may develop
- In disseminated disease, lesions throughout the body
- Granulomatous and suppurative
- Signs:
- Cough and dyspnea
- Skin furuncles (small abscesses) large abscesses, and may ulcer
27
Q
How is Blastomycosis Diagnosed?
A
- Clinical:
- Respiratory disease, differentiate from Nocardiosis and Actinomycosis
- Blastomycin skin test
- Precipitin test
- Laboratory:
- Direct Examination:
- Large budding (Figure 8) yeast cells in exudate or tissue
- Yeast cells are thick-walled and 5-30 microns in diameter
- Not capsulated
- Cultural Examination:
- Mycobiotic Agar
- Grow Slow (10-14 days)
- Hold for 30 days before discarding as negative
- Mycelial phase 25C
- Characteristic conidia, 3-4 microns in diameter, smooth
- Non-pathogenic fungi may have similar appearance, but do not convert to yeast phase at 37 C
- Yeast phase at 37 C on blood agar
- Direct Examination:
