Infectious diseases: Pathology - Fungal infections

Question 1

Five infectious syndromes seen with candida albicans

Answer 1

1. Benign commensal
2. Superficial mucosal infections (oral, vaginal, oesophageal)
3. Superficial cutaneous infections (intertrigo, nappy rash, balanitis, folliculitis, paronychia, onychomycosis)
4. Chronic mucocutaneous (e.g. in T cell defects, endocrinopathy)
5. Invasive/disseminated

Question 2

Eight types of infection seen with disseminated candida infection. What are two complications of disseminated candidiasis?

Answer 2

1. Myocardial abscess
2. Endocarditis
3. Cerebral abscess
4. Meningitis
5. Renal abscess
6. Hepatic abscess
7. Endophthalmitis
8. Pneumonia

Complications:
1. Shock
2. DIC

Question 3

In what groups of patients does disseminated candidiasis commonly occur?

Answer 3

Neutropenic patients

Question 4

Five virulence factors of Candida albicans

Answer 4

1. Phenotype switching: adapts to changes in host environment
2. Adhesins: also involved in intracellular signalling
3. Enzymes: including aspartyl proteinases and catalases
4. Adenosine secretion: blocks neutrophil degranulation
5. Biofilm formation

Question 5

What is the most common cause of fungal endocarditis?

Answer 5

Candida albicans

Question 6

What three endocrinopathies predispose to chronic mucocutaneous candidiasis?

Answer 6

1. Hypoparathyroidism
2. Hypothyroidism
3. Hypoadrenalism

Question 7

What kind of organism is Cryptococcus neoformans?

Answer 7

Encapsulated yeast

Question 8

What infective syndromes are caused by Cryptococcus neoforms in immunocompetent vs immunodeficient hosts?

Answer 8

Immunocompetent host: causes meningoencephalitis
Immunodeficient host (especially those on high-dose steroids): opportunistic infection

Question 9

Three virulence factors of Cryptococcus neoformans

Answer 9

1. Capsule
2. Melanin production
3. Enzymes

Question 10

What kind of organism is Aspergillus fumigatus?

Answer 10

Ubiquitous mold

Question 11

What infective syndromes are caused by Aspergillus fumigatus in immunocompetent vs immunodeficient hosts?

Answer 11

Immunocompetent host: allergic bronchopulmonary aspergillosis
Immunodeficient host (especially in neutropenia, corticosteroids): severe sinusitis, pneumonia

Question 12

Which fungal organism produces aflatoxin? What illness does this cause?

Answer 12

Aspergillus species that grows on peanuts produces aflatoxin
Aflatoxin is carcinogenic and causes HCC

Question 13

Four virulence factors of Aspergillus fumigatus

Answer 13

1. Adhesins
2. Antioxidants
3. Enzymes
4. Toxins

Question 14

What organisms cause mucormycosis?

Answer 14

Bread mold fungi (Mucor, Rhizopus, Absidia, Cunninghamella)

Question 15

List five predisposing conditions for mucormycosis

Answer 15

1. Neutropenia
2. Corticosteroids
3. Diabetes mellitus
4. Iron overload
5. Breakdown of cutaneous borders in burns, surgical wounds, trauma

Question 16

What kind of organism of Pneumocystis jirovecii? What infective syndrome does it cause?

Answer 16

Fungus, often first opportunistic infection in HIV-1
Causes diffuse and dense pneumonia