Primary Systemic Mycoses Flashcards
3 categories of primary systemic mycosis?
1) coccidioidomycosis
2) histoplasmosis
3) blastomycosis
What do all primary systemic mycoses have in common?
- Generalized throughout the body and typically subclinical
- Restricted to a particular geographical area
- Initiated in the LUNGS
- NOT transmissible
Geographical area for coccidioidomycosis?
Southwest- semiarid regions
aka. San Joaquin Fever, Valley Fever
What was inhaled to cause coccidioidomycosis?
Coccidioides immitis spores (from dried up soil/dust)
Describe coccidioides immitis dimorphism
Cool temps (25C) - branching, septate hyphae --> arthrospores Body temp - spherules containing ENDOSPORES in tissues
Two phases of coccidioides immitis: one in soil one in infected tissues
1) Mycelial arthrospore-soil:
Fungi live in dry desert conditions for years –> grow during rainy season (not infectious) –> hyphae develop arthropsores when dry summer months come along (disseminate as arthrocondia) –> become airborne
2) Spherule endospore-infected tissues:
Inhaled arthrospore turns into thick-walled spherule containing endospores–> spherules eventually open and release –> proliferation of infxn.
Primary Pulmonary Coccidioidomycosis
- 60% asymptomatic
- 95% recover from symptomatic (mild flu-like symptoms starting roughly 2 wks. after inhalation)
- 5-8% progress to chronic (cavities and nodules in lungs)- due to failed immune response
Disseminated Coccidioidomycosis (mostly in immunocompromised)
- Less than 1% affected –> rapid, and fatal
- Spread beyond lungs –> lymph –> blood spread
- Present with dramatic sweats, dyspnea at rest, fever, weight loss
- Often skin, bones, joints, and CNS (meningitis)
- Can take weeks to 2 years
Diagnosis for Coccidioidomycosis
Micro: Spherules in sputum, exudate, tissues in KOH
Serology: Coccidioidin Ag to detect antibody to mycelial-phase proteins; serum IgM Ab with primary infections; IgG later
Elevated IgG serum Ab is marker of disseminated (extrapulmonary)
Treatment for Coccidioidomycosis
Fluconazole, Itraconazole, or Amph B
What is the most prevalent mycotic infection in humans and animals?
Histoplasmosis
What are the two varieties of histoplasmosis causing agents?
1) Histo. Capsulatum capsulatum
2) Histo. Capsulatum duboisii
Dimorphism of Histo
Ambient/Cool temps (25C) - branching, septate hyphae –> microcondia and TUBERCULATE (round) macrocondia
Body temp- small, narrow-based, ovoid, budding yeast
Where is Histo normally found?
Soils contaminated with bird dung- chicken coops, roosts, caves, etc.
Who is at high risk for Histo infection?
- Construction; bulldozing decaying buildings
- Smokers
- Children
- Immunocompromised
Acute forms of histoplasmosis
1) Acute asymptomatic pulmonary
2) Acute symptomatic pulmonary: Chest pain while inhaling, fever, cough, chills
Chronic Pulmonary Histoplasmosis
- Fever- may resemble symptoms of pulmonary TB (cough up blood)
- Excessive sweating
- Shortness of breath
- Cough
- Chest Pain
Disseminated Histoplasmosis
- Mouth sores
- Skin Lesions
- Headache
- Fever
Other: can have joint pain, rashes, ERYTHEMA NODOSUM
What is the infectious/inhaled version of Histo?
Microconidia in soil containing bird droppings
Pathogenesis of Histoplasmosis
- 90% inhibited through CMI
Microconidia is inhaled –> develop into yeast and replicate in alveolar MQ –> acute pulm. histo (self-limiting; some nodules heal with calcification) –> chronic pulm. histo (especially in men with emphysema)
**After lung development can take disseminating route to reticuloendothelial tissues and become granulomatous –>DEATH
Geographical area for Histoplasmosis
Central and eastern states, Ohio River Valley, and Mississippi River Valley… Indiana area-ish. and more south.
Because yeast form survive and thrive in MQ like TB, infected individuals will have a similar response in a Histo skin test.
FYI
What percent of the population would likely test positive for Histo ‘round these parts?
90% COMFORTING
Diagnosing Histoplasmosis
- Presence of fungus in sputum, lung tissue, blood, CSF, BM
- Ag test: Capsular Ag in blood, urine, CSF
- X-rays show lung abnormalities- hilar calcifications
Histoplasmosis Treatment
Itraconazole/Amph B
What is the cause of Blastomycosis?
Blastomyces dermatitidis
What immune defect can Blasto cause?
Chronic granulmatous disease
Dimorphism of Blastomyces dermatitidis
Cold- septate, UNBRANCHED, short conidiophores (unicellular)
Heat- Budding yeast cells- double contoured wall with a single bud on wide base
What percent of Blastomyces dermatitidis infections are asymptomatic?
50%
Acute Pulmonary mimic bacterial pneumonia (TB)
- Dry cough, fever –> weight loss, chest pain, persistent cough with thick sputum
- Muscle aches, night sweats, coughing up blood
- Incubation period: 3 weeks to several months
Infection can spread by blood to skin, bone, etc.
- SKIN infection appears as growing raised, bumpy lesions with ulcerating centers on distal extremities,
- Can spread to bones, prostate gland, testes, kidneys (rare)
What is the infectious form of Blastomyces dermatitidis?
Aerosolized conidial mold
Pathogenesis of Blastomycosis
Inhaled as conidia –> transform into yeast –> multiply and may disseminate through blood –> inflammatory responses (neutrophils, followed by MQ) –> GRANULOMA
Geographical area for Blastomycosis
Similar to Histo: South central states along Mississippi and Ohio River. Reaches further north. Sorta looks like bunny ears around Great Lakes. Great Lakes is a buzz … phrase.
Outbreak causing activities:
Recreational activities around river banks, collecting wood, being around organic debris/vegetation
Diagnosing Blastomycosis
- Look in sputum, pus, tissue exudates, urine, biopsies
- Thick-walled yeast cells- barely attached buds seen in microscope
- 2 weeks to culture
Treatment Blastomycosis
Itraconazole, Fluconazole, Amph B (more serious)
It appears as though the treatment for Primary Mycoses is/are:
Itraconazole is always a safe bet and Amph B for more serious. Sometime Fluconazole is thrown in.
