Opportunistic Fungal Infections

Question 1

cryptococcus neoformans, c. gatti epi

Answer 1

cause more life threatening infections than any other fungus

causes encephalitis

subsaharan africa and Latin america

neoformans- widely in nature, soil w/ bird droppings

gatti- trees

common in HIV

Question 2

cryptococcus neoformans, c. gatti pathogenesis

Answer 2

polysaccharide capsule is distinguishing feature- composed of GXM that are necessary for virulence- prevents phagocytosis

urease positive

inhalation of spores cannot be eliminated. uses phenol oxidases to produce melanin from dopamine. the melanin protects it from oxidative damage

can spread from lungs to CNS in compromised individuals via microcappilaries

Question 3

cryptococcus neoformans, c. gatti immunity

Answer 3

innate recepotrs TLR, CD14 recognize and activate cell mediated immunity Th1

Question 4

cryptococcus neoformans, c. gatti clinical features

Answer 4

chronic meningioencephalitis

slow onset

headache, stiff neck, body aches, respiratory symptoms

Question 5

cryptococcus neoformans, c. gatti diagnosis

Answer 5

presence of capsular Ag via plasma, urine CSF

CGB agar- turns blue

Question 6

cryptococcus neoformans, c. gatti treatment

Answer 6

flucytosine, amphtericin B, fluconazole, itraconzaole

Question 7

aspergillis epi

Answer 7

fumigatus and flavus- two major causes of disease

grow in mold form only (hyphae)- no dimorphism

easily airborne spores

inhalation causes disease in suppressed

fumigatus also can cause an allergic reaction

seen in hematopoietic stem cell transplants, organ transplants, chronic granulomatous disease, and HIV

Question 8

aspergillis pathology

Answer 8

inhaled and germ tubes emerge to colonize cavity lesions with hyphae

quick dessemination is observed without therapy

Question 9

aspergillis immunity

Answer 9

innate immune system critical- alveolar macrophages and neutrophils

Pentraxin 3, a soluble pattern recognition receptor, crucial

Th1 response important

Question 10

aspergillis clinical features

Answer 10

cough, fever, chest pain, SOB

Question 11

aspergillis diagnosis

Answer 11

biopsy

serum test

IgE Abs specific for aspergillis

Question 12

aspergillis Abs

Answer 12

voriconazole, amphotericin B

Question 13

mucor, rhizopus

Answer 13

grow in molds only, not dimorphic

however, grow in hyphae at right angles rather than Y shaped

spreads thru air

special population: diabetic ketoacidosis

Question 14

mucor, rhizopus pathology

Answer 14

similar to aspergillis

spores germinate into hyphae and invade tissue

Question 15

mucor, rhizopus immunity

Answer 15

need intact innate and adaptive systems, unknown else wise

Question 16

mucor, rhizopus presentation

Answer 16

similar to aspergillis

looks like bacterial sinusitis, headaches and fever in frontal or retroorbital regions

Question 17

mucor, rhizopus diagnosis/treatment

Answer 17

biopsy

surgical debridement and amphotericin B

Question 18

pneumocystis jiroveci epi

Answer 18

CANNOT BE CULTURED

exists as a cyst of sporozoites that rupture and grow into trophozoite forms

animals are not a resevoir

asymptomatic infections are common

similar to parasites- sensitive to antiparasitic drugs

no ergosterol in membrane

Question 19

pneumocystis jiroveci pathogenesis

Answer 19

loss of CD4 immunity leads to susceptibility

transmission via aerosols

inhaled cysts produce inflammation- causes plasma cells to produce “frothy exudate” that blocks O2 exchange and leads to pneumonia

Question 20

pneumocystis jiroveci immunity

Answer 20

CD4 cells critical

killing of cells done by alveolar macrophages via PRRs

over activation of immune CD8 cells can cause significant damage

Question 21

pneumocystis jiroveci symptoms

Answer 21

sudden onset fever, cough, dypnea, tachypnea,

x-ray = interstial pneumonia

Question 22

pneumocystis jiroveci risk factors

Answer 22

low CD4

Question 23

pneumocystis jiroveci diagnosis and treatment

Answer 23

stain w/ methanamine silver or fluorescent stain w/ Abs to diagnose

chemoprophylaxis in pts with CD4 deficits

trimethoprim-sulfamethoxazole is drug of choice

Question 24

mold in the environment

Answer 24

emerging evidence that mold in the house hold should be avoided

inhalation of spores or mycotoxins can cause immune mediated responses that are damaging

causes a hypersensitive rxn associated with Th2

symptoms: nasal stuffiness, eye irritation, wheezing, skin irritation

people with asthma or chronic lung disease more at risk

indoor environment w/ high levels of moisture = more mold and more spores. more common in lower SES