Flashcards in Fungal and Immunocompromised Pneumonia Deck (72):
What are the types of fungal infections?
-superficial and cutaneous mycoses
-subcutaneous (skin, lymphatics, subQ tissue)
What causes endemic mycoses?
Notes about dimorphic fungi
-most common etiologic agents of pulmonary infection by fungi
-infection results from inhalation of spores that mold forms in soil
What does 'dimorphic' mean?
-grow as yeast in human tissue and as mold at room temp
What happens with spores of dimorphic fungi are inhaled?
they differentiate into yeasts or spherules. Most are self-limited but all can cause pneumonia and disseminate
What are some dimorphic fungi?
Where is Histoplasma capsulatum endemic?
Mississippi and Ohio River
Where does Histoplasma capsulatum grow?
soil and bird droppings
How does Histoplasma capsulatum infection present?
-mostly asymptomatic pulmonary infection
-but can have fever, chills, cough, chest pain
In AIDS, Histoplasma capsulatum can disseminate. What organs are typically affected?
-Skin (rash, nodules)
Tissue biopsy of positive Histoplasma capsulatum will show what?
oval yeast cells within macrophages
How else can Histoplasma capsulatum be diagnosed?
-Urinary antigen (good for AIDS patients)
How does Histoplasma capsulatum show on CXR?
What are two possible skin manifestations of Histoplasma capsulatum infection?
Note about skin rashes in Histoplasma capsulatum
seen in disseminated Histo (rash is rare, but common in AIDS/immunocompromised)
What is erythema nodosum?
tender nodules that present on extensor surfaces (tibia and ulna skin). Result from delayed hypersensitivity response to fungal antigen and is an indicatory of poor prognosis (not specific to histo but also seen in coccidioides and TB)
Aka desert bumps
Where is Blastomyces dermatitidis endemic?
Ohio/Mississippi River Valley, Missouri, and Arkansas River basins (grows in moist soil)
How does Blastomyces dermatitidis present?
asymptomatic respiratory illness, 50% will have cough, chest pain, sputum, fever/night sweats
most resolve spontaneously
Disseminated Blastomyces dermatitidis results in what?
ulcerated granulomatous lesions of the skin (70%), bone (33%), GI tract (25%), and CNS (10%). Seen in both immunocompetent and compromised patients
What does tissue biopsy of Blastomyces dermatitidis show?
thick-walled yeast cells with **single broad-based bud**
How is Blastomyces dermatitidis diagnosed?
-CXR (lobar consolidation)
How is Histoplasma capsulate treated?
Ampho B for severe and Itra otherwise
How is Blastomyces dermatitidis treated?
Ampho B for severe and Itra otherwise
Where is Coccidioides immitis endemic?
Southwest and Latin America
Describe the pathogenesis of Coccidioides immitis
In the lungs, large spherules form and filled with endospores. Upon rupture, endospores are released and differentiate into new spherules
How does Coccidioides immitis present?
-mild flu-like illness with fever and cough ('valley fever') in 10%
How common is dissemination in Coccidioides immitis?
1% (to bone, meninges, and skin)
What ethnicities are at increased risk for dissemination of Coccidioides immitis?
-AA, Filipinos, and women in 3rd trimester
____ is common with Coccidioides immitis
How is Coccidioides immitis treated?
-Ampho for persistent lung lesions or disseminated
-Fluconazole for meningitis
Where is Paracoccidioides brasiliensis endemic?
rural latin america, especially brazil
How does Paracoccidioides brasiliensis present?
mild respiratory infection which can disseminate and develop oral, nasal, and facial nodular ulcerated lesions and submandibular LAD
How is Paracoccidioides brasiliensis diagnosed?
-tissue biopsy shows yeast cells with multiple buds (aka pilot well configuration)
Treatment of Paracoccidioides brasiliensis?
-several months of Itra
-Ampho for severe
Where is Aspergillus fumigatus found and how does it exist?
worldwide in a mold with ACUTE branching septate hyphae that grows on decaying vegetation producing chains of conidia
Features of Aspergillus fumigatus infection.
-fungus ball formed within cavities of lungs (can produce hemptysis)
-allergic infection of bronchi that produces asthmatic symptoms and high IgE titer
-invasive PNA with hemorrhage, infarction, and necrosis
What patient population is especially at risk for invasive PNA form of Aspergillus fumigatus?
those with hematologic malignancies and neutropenia
How does Aspergillus fumigatus present upon CT?
Can have single or multiple nodules with cavitation and a a ’halo’ sign which are areas of focal hemorrhage around a lesion
How is Aspergillus fumigatus treated?
-**Voriconazole** for invasive disease (ampho B and echinocandins alternatives if not well-tolerated)
-remove fungus balls
What is the treatment for ABPA?
steroids and antifungals
Opportunistic infections caused by bread mold fungi (Mucor, Rhizomes, Cunninghamella, Lichtheimia)
What are some risk factors for Mucormycosis?
How is Mucormycosis transmitted?
airbourne spores that invade tissue and blood in those with reduced host defenses
How does Mucormycosis present?
-invasive rhinocerebral sinusitis
-frontal lobe abscesses
How does invasive rhinocerebral sinusitis occur?
originates in the paranasal sinuses and spreads to the orbit, hard palate, and brain and carries a high mortality rate
How is Mucormycosis diagnosed?
tissue biopsy with nonseptate broad hyphae with frequent RIGHT ANGLE branching; spores in a sporangium
How is Mucormycosis treated?
treat underlying disorder + Ampho and surgical removal of necrotic tissue
How does Pneumocystis jiroveci exist?
Pneumocystis jiroveci is the most common cause of ___ in immunocompromised patients
Pathogenesis of Pneumocystis jiroveci (PCP)
cysts in alveoli produce inflammation, resulting in frothy exudate that block oxygen exchange (organism does not invade lung tissue)
How is Pneumocystis jiroveci cleared?
CD4 T cells recruit monocytes and macrophages which clear the organism (thus, AIDS is a major risk factor)
How does Pneumocystis jiroveci present?
-Dry cough, progressive dyspnea
CXR of PCP
How is PCP diagnosed?
-Cysts in lung biopsy or from bronchoscopy fluids
-fluorescent AB staining
-PCR on RT specimens
How are cysts identified from PCP?
methenamine silver, Giemsa stain
How is PCP treated?
-Cotrimoxazole (Bactrim) (1st line)
2nd line options for PCP
Prophylaxis for AIDS patients with CD4 count below 200?
Bactrim, Dapsone, or Atovaquone
How does Cryptoococcus neoformans exist?
yeast in soil and PIGEON droppings that has the appearance of oval budding yeast with a wide polysaccharide capsule
What disease does Cryptoococcus neoformans cause?
meningitis in immunocompromised (especially in AIDS)
PNA in immunocompromised AND competent persons
How does Cryptoococcus neoformans induced PNA present in immunocompetent persons?
asymptomatic or mild respiratory symptoms
How does Cryptoococcus neoformans induced PNA present in immunocompromised persons?
fever, chest pain, dyspnea, cough, and hemoptysis
T or F. CMV is a herpes virus
How does CMV exist in the body?
enters latent state primarily in monocytes and can be reactivated when cell-meidtaed immunity is decreased
What patients is CMV commonly reactivated?
-renal and stem cell transplant recipients
What does activation of CMV in AIDS patients cause?
colitis and retinitis (typically NOT pneumonitis)
Two buzz words with CMV
ground glass appearance and inclusion bodies on H&E
What causes Nocardiosis?
Describe Nocardia asteroides
gram+ aerobe found in soil with thin branching filaments
In immunocompromised patients, Nocardia asteroides can disseminate and has a predilection for ____
brain tissue (can cause brain abscesses)
How is Nocardiosis diagnosed?
gram stain/acid-fast stain; culture