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
