opportunistic fungi (mycoses) Flashcards
3 yeasts and 2 molds that are opportunistic in immunocomprimised?
candida, cryptococcus, and pneumococcus = yeasts aspergillus and mucorales = molds
if germ tube +, infection is likely ____ and should be treated with _____
candida treat with azole
a patient with pulmonary symptoms and acute angle branching organisms
aspergillus
a yeast with a large capsule is most likely
cryptococcus
risk factors for fungal infection
• Immunodeficient • Transplants (bone marrow or organ) • Malignancy • ICU stay/major surgery • Parenteral nutrition • Very old and very young age
patient with DKA and facial ischemia
mucormycosis
candida albicans characteristics
o Dimorphic, Budding yeast with pseudohyphae (buds that don’t detach and form chains), true hyphae, and germ tubes ; can be a part of normal flora
o Germ tubes: No septum separating tube from yeast cell (Used to diagnose C. albicans from other Candida species)
o Pseudohyphae: Separate cells connected by sequential budding; always a septum (constriction) at branching points
o True hyphae: No septum at branch points (continuous cells). Have pores in septae, enabling transit of nutrients/enzymes.
candida albicans
candida albicans
risk factors for candida infection
antibiotics –> allow increased candida growth in gut
neutropenia –> systemic c. albicans infection
t cell suppression –> mucosal candida infection
total parenteral nutrition
central venous lines, surgery, chemotherapy, gastric acid suppression
what do you need to see to diagnosis candida?
budding yeast and pseudohyphae at 20 degrees C
germ tubes at 37 degrees C
treatment for candida?
azoles (fluconazole)
amphotericin B
clinical presentation of candida infection
in normal hosts: mucosal rashes (oral thrush, vaginitis, diaper rash)
in immunocompromised (especially AIDS or neutropenic): esophagitis (white plaque in throat) and pseudomembranous candidiasis (white plaque that wipes away; painful) –> thrush spreads down GI tract and blood stream to organs (heart, eyes, osteomyelitis, liver, spleen)
—can cause–>
endocarditis in IV drug users
septicemia due to indwelling catheters (e.g. subclavian catheter)
disseminated candidiasis
local infection is due to T-cell deficiency while systemic infection is due to neutropenia
cryptococcus characteristics
Yeast with capsular polysaccharide
- Spherical/oval, encapsulated
- India ink shows large capsules around budding yeast
- Transmission via inhalation of aerosolized fungi (lungs–> blood –> CNS)
- C. neoformans - soils; pigeon feces
- C gatii - eucalyptus tree
cryptococcus neoformans yeast
cryptococcus yeast
clinical presentation of cryptococcus/cryptococcosis
inhaled and spreads hematogenously to brain
—meningitis is most common (h/a, fatigue, lethargy, coma, memory loss over 2-4 weeks) = “soap bubble” lesions in brain
can also cause encephalitis
—pneumonia is 2nd most common (fever, chest pain, cough, and sputum)
—skin and bone infections
diagnosis of cryptococcus
india ink visualization
–> polysaccharide capsule with wide capsular halo (only fungus with a polysaccharide capsule); monomorphic
detect polysaccharide capsular antigen in CSF
culture > anigen > microscopy
cryptococcus treatment
fluconazole for mild (azole antifungal)
amphotericin B (systemic antifungal) with 5FC(flucystosine/antifungal) for severe
pneumocystis jirovecii characteristics
- The Most opportunistic infection in AIDs; also occurs with immunosuppression and chronic corticosteroids
- Unable to grow in culture; probably contracted via inhalation
yeast with lung preference
pneumocystis jirovecii
pneumocystosis
infection by pneumocystis jirovecii
pneumonia (cough, SOB, fever; not alot of sputum) with bilateral perihilar interstitial infiltrates
treatment of pneumocystis jiroveci/pneumocystosis
Treatment =TMP-SMX, pentamidine, or dapsone +/- corticosteroids if pO2 is
Prophylaxis = same; start when CD4
aspergillus characteristics
monomorphic mold
Hyphal characteristics = uniform in width with parallel contours, regular septae, progressive tree-like pattern, dichotomous branching(two equal parts), and acute angle branching
aspergillus mold
acute angle branching of aspergillus mold
where is aspergillus found?
tramission via inhalation of spores
found in hospital showerheads and water; soil water air
primary airborne fungus
3 diseases caused by aspergillus
allergic bronchopulmonary aspergillosis (ABPA) = asthma-like allergic reaction (type 1 IgE hypersensitivity) in airways that causes cough, hemoptysis, chest pain and sputum –> inflammation –> bronchiectasis
—-usually in patients with underlying asthma or CF
aspergilloma = preexisting fibrocavitary lung disease; seen in TB patients (or other granulomatous disease) –> “fungus ball” forms in pre-existing lung cavities
invasive aspergillosis = invasive infection of the lung; pulmonary infiltrates and fever/wheezing/hemoptysis in neutropenic patient; bronchial and parenchymal involvement
—usually in immunocompromised; disseminated via blood
infiltrate seen on radiograph and CT
how to treat ABPA (allergic bronchopulmonary aspergillosis)
corticosteroids + antifungal (itraconazole)
treatment for aspergilloma
surgical resection + antifungal
invasive aspergillosis treatment
voriconazole or lipid formulation of amphoB
early indication specific lab test for aspergillus
Serum galactomannan
cause of mucormycosis
infection due to mucorales fungi
(rhizopus, rhizomucor, mucor, absidia, cunninghamella)
molds with 90 degree branching
hyphae with NO septae
inhaled –> angioinvasive –> tissue infarction and necrosis
risk factors for mucormycoses
common in diabetics/DKA
neutropenia
aseptate and 90 degree branching
mucormycosis
presentation of mucormycosis
rhinocerebral infection (mucormycosis)
—-frontal lobe abscesses
—-paranasal swelling
—-hemorrhage from nose and eyes (black/purple lesions)
fungi also penetrate blood vessel walls –> results in infarction and necrosis
treatment for mucormycosis
- Control diabetes
- Surgical debridement
- amphoB
