opportunistic fungi (mycoses)

Question 1

3 yeasts and 2 molds that are opportunistic in immunocomprimised?

Answer 1

candida, cryptococcus, and pneumococcus = yeasts aspergillus and mucorales = molds

Question 2

if germ tube +, infection is likely ____ and should be treated with _____

Answer 2

candida treat with azole

Question 3

a patient with pulmonary symptoms and acute angle branching organisms

Answer 3

aspergillus

Question 4

a yeast with a large capsule is most likely

Answer 4

cryptococcus

Question 5

risk factors for fungal infection

Answer 5

• Immunodeficient • Transplants (bone marrow or organ) • Malignancy • ICU stay/major surgery • Parenteral nutrition • Very old and very young age

Question 6

patient with DKA and facial ischemia

Answer 6

mucormycosis

Question 7

candida albicans characteristics

Answer 7

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.

Question 8

Answer 8

candida albicans

Question 9

Answer 9

candida albicans

Question 10

risk factors for candida infection

Answer 10

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

Question 11

what do you need to see to diagnosis candida?

Answer 11

budding yeast and pseudohyphae at 20 degrees C

germ tubes at 37 degrees C

Question 12

treatment for candida?

Answer 12

azoles (fluconazole)

amphotericin B

Question 13

clinical presentation of candida infection

Answer 13

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

Question 14

cryptococcus characteristics

Answer 14

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

Question 15

Answer 15

cryptococcus neoformans yeast

Question 16

Answer 16

cryptococcus yeast

Question 17

clinical presentation of cryptococcus/cryptococcosis

Answer 17

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

Question 18

diagnosis of cryptococcus

Answer 18

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

Question 19

cryptococcus treatment

Answer 19

fluconazole for mild (azole antifungal)

amphotericin B (systemic antifungal) with 5FC(flucystosine/antifungal) for severe

Question 20

pneumocystis jirovecii characteristics

Answer 20

• 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

Question 21

Answer 21

pneumocystis jirovecii

Question 22

pneumocystosis

Answer 22

infection by pneumocystis jirovecii

pneumonia (cough, SOB, fever; not alot of sputum) with bilateral perihilar interstitial infiltrates

Question 23

treatment of pneumocystis jiroveci/pneumocystosis

Answer 23

Treatment =TMP-SMX, pentamidine, or dapsone +/- corticosteroids if pO2 is

Prophylaxis = same; start when CD4

Question 24

aspergillus characteristics

Answer 24

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

Question 25

Answer 25

aspergillus mold

Question 26

Answer 26

acute angle branching of aspergillus mold

Question 27

where is aspergillus found?

Answer 27

tramission via inhalation of spores

found in hospital showerheads and water; soil water air

primary airborne fungus

Question 28

3 diseases caused by aspergillus

Answer 28

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

Question 29

how to treat ABPA (allergic bronchopulmonary aspergillosis)

Answer 29

corticosteroids + antifungal (itraconazole)

Question 30

treatment for aspergilloma

Answer 30

surgical resection + antifungal

Question 31

invasive aspergillosis treatment

Answer 31

voriconazole or lipid formulation of amphoB

Question 32

early indication specific lab test for aspergillus

Answer 32

Serum galactomannan

Question 33

cause of mucormycosis

Answer 33

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

Question 34

risk factors for mucormycoses

Answer 34

common in diabetics/DKA

neutropenia

Question 35

Answer 35

aseptate and 90 degree branching

mucormycosis

Question 36

presentation of mucormycosis

Answer 36

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

Question 37

treatment for mucormycosis

Answer 37

• Control diabetes
• Surgical debridement
• amphoB