Micro Pulmonary fungal infections 1

Question 1

What are the major themes of systemic mycoses

Answer 1

environmental (spores/fungi in soil) - not person-to-person, inhaled into lungs, thermal dimorphism, range of severity

Question 2

What is the differential for systemic mycoses? What is the difference between the two?

Answer 2

TB

source for TB is foreign crowds, systemic mycoses is american dirt

Question 3

Coccidioides form

Answer 3

dimorphic: mold in soil, spherule in tissue (classic to coccidoides)

Question 4

What are the forms of coccidioides in the soil?

Answer 4

hyphae with alternating arthrospores and empty cells (arthrospores carried in the wind)

Question 5

Pathogenesis coccidioides

Answer 5

arthrospores are inhaled and change for to spherules in lung (thick, double-refractive wall that is filled iwth endospores), wall ruptures to release endospores and develop into new spherules, spreading by direct extension, while growth leads to granulomatous lesions

Question 6

What type of immunologic response is there to coccidioides?

Answer 6

CMI delayed hypersensitivity response (infection contained in granulomas in lung)

Question 7

What happens in a immunosuppressed patient with coccidioides?

Answer 7

disseminated infection by hematogenous spread, primarily seen in bones and meninges

Question 8

How is coccidioides diagnosed?

Answer 8

PPD with coccidioidin or spherulin (+ if exposed with cleared or contained infection and - if unexposed or DISSEMINATED infection)

Question 9

Contained coccidioides infection?

Answer 9

asymptomatic, +PPD, influenzealike illness (fever, cough), 50% have lung changes on X-ray, 10% develop erythema nodosum or arthralgias

Question 10

Erythema nodosum

Answer 10

sign of good strong immune response: “desert bumps” - red, tender nodules on exterior surfaces like lower legs, a delayed cell-mediated hypersensitivity to fungal antigens

Question 11

Disseminated coccidioides infection?

Answer 11

affects meninges, bone (osteomyelitis), and skin (nodules)

-disseminates MC in AA, Filipino, late-pregnancy

Question 12

Diagnostic feature of coccidioides

Answer 12

• spherules on microscopic exam!!!
• cultures of sabouraud’s agar (cultures are infectious!)
• serology for exposure, titers (spikes if disseminating)

Question 13

treatment of coccidioides

Answer 13

• none for mild disease
• persisting lung lesions or disseminated: amphotericin B or itraconazole
• meningitis: fluconazole

Question 14

endemic areas coccidioides

Answer 14

SW US

Question 15

histoplasma form

Answer 15

dimorphic: mold in soil, yeast in tissue

Question 16

what are the two asexual spores formed by histoplasma?

Answer 16

1. tuberculate macroconidia (grows in culture) - thick walls and fingerlike projections
2. microconidia (infectious form from environment) - smaller, thin, smooth-walled

Question 17

where is histoplasma endemic? mode of transmission?

Answer 17

ohio and mississippi river valleys - transmitted by soil and bird droppings (starlings and bat guano esp)

Question 18

histoplasma pathogenesis

Answer 18

spores are inhaled, engulfed by macrophages, survive endocytosis, replicate as yeasts in macrophages and spread through the body

Question 19

how does histoplasmosis survive endocytosis?

Answer 19

produces bicarbonate and ammonia, raising pH and inactivating hydrolytic enzymes

Question 20

how do healthy people’s immune response respond to histoplasmosis?

Answer 20

CMI forms granulomas, calcify, and contain infection (may see erythema nodosum)

Question 21

histoplasmosis in immunocompromised/immunosuppressed

Answer 21

pancytopenia and ulcerated lesions on tongue

Question 22

histoplasmosis exam

Answer 22

cavitary lung lesions that cause the “jug sound”, granulomas in liver and spleen, tongue lesions in disseminated disease

Question 23

labs for histoplasmosis

Answer 23

• tissue biopsy or bone marrow aspirate for oval yeast cells within macrophages
• cultures on sabouraud’s agar (25 tuberculate macroconidia, 37 yeast)

Question 24

treatment for histoplasmosis

Answer 24

if spreading, itraconazole
if disseminated, amphotericin B
if meningitis fluconazole

Question 25

blastomyces forms

Answer 25

dimorphic: mold form (hyphae with pear-saped conidia - infectious by inhalation)
yeast form (round with double refractive wall and single broad-based bud)

Question 26

where is blastomyces endemic

Answer 26

eastern north america and great lakes region (wet, rich soil)

Question 27

blastomyces pathogenesis

Answer 27

infection by inhalation of conidia, 50% asymptomatic, immunosuppression or preexisitng pulmonary disease predisposes to dissemination

Question 28

diagnosis of blastomyces

Answer 28

1. mild: nonspecific flulike
2. pneumonia: high fever, chills, cough with sputum, chest pain
3. chronic: looks like TB
4. fast severe: ARDS
   may also have skin lesions

Question 29

labs for blastomyces

Answer 29

tissue biopsy: thick-walled yeast cells with single, broad-based buds
culture: hyphae with small pear-shaped conidia

Question 30

treatment of blastomyces

Answer 30

itraconazole
severe: amphotericin B
surgical excision of loci sometimes necessary

Question 31

paracoccidioides forms

Answer 31

mold form: thin, septate hyphae

yeast form: thick walled with multiple budes

Question 32

paracoccidioides endemic

Answer 32

latin america

Question 33

paracoccidioides also known as

Answer 33

south american blastomycosis (paracoccidioides BRASILiensis)

Question 34

paracoccidioides pathogenesis

Answer 34

spores inhaled, early lesions in lung, asymptomatic common, more severe = oral mucous membrane lesions, lymph node enlargement

Question 35

paracoccidioides disease

Answer 35

1. juvenile type/acute form: RARE
   - peds/immunosuppressed, more severe with skin lesions, fever, malaise, weight loss, lymphadenopathy and hepatosplenomegaly
2. chronic adult form: MC
   - less severe, long latency (30 yr), pulmonary symptoms, oral and skin lesions

Question 36

labs for paracoccidioides

Answer 36

pus or tissue samples: yeast cells with multiple buds

• culture is 2-4 weeks
• serologic testing: significant antibody titers correlate with active disease

Question 37

treatment of paracoccidioides

Answer 37

oral itraconazole for 6 months

Question 38

how does paracoccidioides differ from the other systemic mycoses?

Answer 38

more opportunistic - not seen in US (latin america)