Opportunistic Fungal Infections Flashcards
properties of Candida albicans
- alba = white
- dimorphic
- forms pseudohyphae and budding yeasts at 20 deg C
- germ tubes at 37 deg C
what does Candida albicans cause?
- systemic or superficial fungal infections
- causes oral and esophageal thrush in immunocompromised (neonates, steroids, diabetes, AIDS)
- vulvovaginitis (diabetes, use of antibiotics)
- diaper rash
- endocarditis (IV drug users)
- disseminated candidiasis (to any organ)
- chronic mucocutaneous candidiasis
Candida albicans–treatment
- topical azole for vaginal
- nystatin, fluconazole, or caspofungin for oral/esophageal
- fluconazole, caspofungin, or amphotericin B for systemic
properties of Aspergillus fumigatus
- septate hyphae that branch at 45 deg Acute Angle
- produces conidia in radiating chains at end of conidiophore
what can Aspergillus fumigatus cause?
- causes invasive asperillosis–especially immunocompromised and those with chronic granulomatous disease
- can cause aspergillomas in pre-existin lung cavities, especially after TB infection
- som species of Aspergillus produce Aflatoxins–associated with hepatocellular carcinoma
Allergic bronchopulmonary aspergillosis (ABPA)
- hypersensitivity response associated with asthma and cystic fibrosis
- may cause bronchiectasis and eosinophilia
properties of Cryptococcus neoformans
- 5-10 micrometers with narrow budding
- heavily encapsulated yeast
- not dimorphic
- culture on Sabourand agar
- highlighted with India Ink (clear halo) and mucicarmine (red inner capsule)
Cryptococcus neoformans:
where is it found
how is it acquired
- found in soil, pigeon droppings
- acquired thru inhalation with hematogenous dissemination to meninges
Cryptococcus neoformans–detection in lab
- latex agglutination test detects polysaccharide capsular antigen and is more specific
what does Cryptococcus neoformans cause?
- cryptococcosis
- cryptococcal meningitis
- cryptococcal encephalitis–soap bubble lesions in brain
- primarily in immunocompromised
properties of Mucor & Rhizopus spp.
- irregular, broad, nonseptate hyphae branching at wide angles
what does Mucor & Rhizopus spp. cause? How does it proliferate?
- Mucormycosis
- causes disease mostly in ketoacidotic diabetic and/or neutropenic patients (ie. leukemia)
- fungi proliferate in blood vessel walls, penetrate cribriform plate, and enters brain
- rhinocerebral, frontal lobe abscess
- cavernous sinus thrombosis
- headache, facial pain, black necrotic eschar on face
- may have cranial N involvement
Mucor & Rhizopus spp.–treatment
- surgical debridement
- amphotericin B
properties of Pneumocystis jirovecii
- yeast like fungus
- inhaled
- most infections are asymptomatic
- diffuse bilateral ground glass opacities on CXR/CT
- disc shaped yeast seen on methenamine silver stain of lung tissue
what does Pneumocystis jirovecii cause?
- causes Pneumocystis pneumonia (PCP)–a difuse interstitial pneumonia
what predisposes you to Pneumocystis jirovecii infection?
- immunosuppression like AIDS
Pneumocystis jirovecii–treatment/prophylaxis
- TMP-SMX
- pentamidine
- dapsone (prophylaxis only)
- atovaquone
when to start prophylaxis for possible Pneumocystic jirovecii infection?
- start prophylaxis when CD4+ count drops to < 200 cells/mm3 in HIV patients
properties of Sporothrix schenckii
- Sporotrichosis
- dimorphic
- cigar shaped budding yeast that grows in branching hyphae with rosettes of conidia
- lives on vegetation
what does Sporothrix schenckii cause?
- when spores are traumatically introduced into the skin, typically by a thorn (“rose gardener’s disease”), cause local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis)
- disseminated disease possible in immunocompromised host
Sporothrix schenckii–treatment
- itraconazole
- potassium iodide
- “Plant a rose in the pot.”
