Lecture 15: Mycology 2 Flashcards
What are the 3 most common systemic mycoses in the USA?
-Blastomycosis
-Histoplasmosis
-Coccidioidomycosis
Systemic fungal pathogens are primarily what type of pathogen?
True pathogens- that don’t require an immunocompromised host
Systemic fungal infections for Blastomycosis can dissipate to what organs?
-skin
-bone
-genitourinary tract
Systemic fungal infections for Histoplasmosis can dissipate to what organs?
-liver
-spleen
-lymph nodes
-bone marrow
Systemic fungal infections for Coccidioidomycosis can dissipate to what organs?
-CNS
-bone
Systemic fungal infections for Paracoccidioidomycosis can dissipate to what organs?
Mucosa of the mouth and nose
All systemic mycoses begin as
Pulmonary infections
-after spore production from the fungi found in the soil and feces of birds and bats. The spores become airborne.
When inhaled, spores cause a primary pulmonary infection
Blastomycosis
-transmission
-found in
-Geophilic transmission!- Canadian provinces that border the Great Lakes. Endemic to central & southeast USA
-Found in soil and decaying vegetation (fertilizers & dead animals)
Dead Animals= birds and bats???
Blastomycosis
Symptoms
-asymptomatic
-primary pulmonary blastomycosis
acute pulmonary disease = pleuritic chest pain, fever, chills, resembles bacterial pneumonia
chronic pneumonia = hemoptysis, fatigue, night sweats, resembles TB or lung cancer
Blastomycosis Dissemination
SKIN, BONE,GENITOURINARY TRACT
-cutaneous blastomycosis (begin as subcutaneous nodules that ulcerate) (results in irreversible wart-like scars)
-osteoarticular blastomycosis
-brain abscess = Immunocompromised
-genitourinary = men (painful urination, prostate affected)
Pathogenesis for blastomycosis
-dimorphic fungi
-conidia are phagocytosed but if they escape they transform to yeasts (greater-resistance)
being a yeast allows for dissemination via blood and lymphatic circulations an effective TH1 will prevent this dissemination but if TH1 lowers and TH2 increases dissemination will occur.
Diagnosis Blastomycosis
Treating blastomycosis mild to severe
-demonstrate thick-walled yeast with broad based attachment … confirm with culture
-treatment
Mild to moderate cases= itraconazole
Severe/disseminated cases= amphotericin B
Histoplasmosis
-transmission
-found in
Geophilic transmission: highly endemic to the Ohio-Mississippi river
Found in bird and bat remaining
Histoplasmosis symptoms
-acute vs. chronic
Acute pulmonary histoplasmosis
-asymptomatic
-flu-like symptoms
-self-limiting
chronic pulmonary histoplasmosis
-occurs in patients with underlying pulmonary disease (resembles TB, night sweats, fever)
Dissemination of Histoplasmosis
-acute vs. subacute
occurs more often in immunocompromised and CHILDREN
-acute presentation =
respiratory failure, shock, coagulopathy and multi-organ failure. fatal days to weeks (untreated)
-subacute = slower disease course
hepatosplenomegaly, thrombocytopenia, fever, weight loss are common. Can include meningitis, ulcers of oral mucosa, GI ulcers w/ bleeding. fatal days to months if left untreated
Histoplasmosis oral lesions
-tongue
-palate
-buccal mucosa
Pathogenesis Histoplasmosis
-dimorphic
-yeast live in and spread inside by a phagocyte. (The WBC does not inhibit this growth)
-cell-mediated is key (granuloma to contain the infection) yeast can escape and cause a relapse of diseases
Diagnosis Histoplasmosis
1st Staining: bone marrow, bronchial lávate fluid, sputum
2nd culture: ONLY WAY TO DEFINITIVELY DIAGNOSE
Treatment for histoplasmosis
Mild- supportive care
Moderate to severe pulmonary- Amphotericin B, then Itraconazole
Chronic pulmonary - Itraconazole
Disseminated histoplasmosis- Amphotericin B, then itraconazole (AIDS patients may require lifelong itraconazole)
VS. BLASTOMYCOSIS
Mild to moderate: itraconazole
Severe & disseminated patients: Amphotericin B
Coccidioidomycosis
-transmission
-found in
-geophilic transmission
-most common in late/summer/early fall when soil dries… during dry seasons
Coccidioidomycosis
-primary Coccidioidomycosis
-secondary Coccidioidomycosis
Primary
-most common
-asymptomatic in most cases
-Flu-like symptoms (fever, chills, night sweats, cough…)
Secondary
-chronic
-nodules, cavitary disease, or progressive pulmonary disease
Coccidioidomycosis dissemination and its risk factors
1% of secondary Coccidioidomycosis patients
Risk factors
-males
-3rd trimester pregoooo
-mortality exceeds 90% w/o treatment
-50% of dissemination ends in meningitis (however it can be multi-organ)
Pathogenesis for coccidioides
dimorphic fungus
-begins w/ inhalation of arthroconidia
-in bronchioles… form spherules
-spherules rupture and release endospore
-phagocytosis of endospore =acute pulmonary inflammation
If infection is not cleared = chronic inflammation (granuloma) “protective immunity follows infection”
Diagnosis for Coccidioidomycosis
-Clincial specimen (preferred)
-morphological differences in spherules allow differentiation b/w the two pathogens.
-IgM and IgG = ELISA
Treatment for coccidioidomycosis
-patients w/ no risk factors for dissemination
-patients w/ risk factors for dissemination
-secondary Coccidioidomycosis
W/o risk:
-asymptomatic air self-limiting
W/ risk
-Amphotericin B, then Intraconzole
secondary Coccidioidomycosis
-chronic cavitary disease = itraconazole
-meningeal = fluconazole
