Microbiology - Fungal Infections

Question 1

How are fungal infections classified?

Answer 1

1. Yeasts Vs Moulds = dimorphism (yeast during infection, mould in nature)
2. Superficial (skin, hair, nails) Vs Deep-seated (systemic)

Question 2

What are some superficial infection-causing fungi?

Answer 2

• Tinea
• Pityriasis

Question 3

How are superficial fungal infections diagnosed?

Answer 3

• Wood Lamp

Question 4

What are some features of a Tinea infection and what treatment do they need?

Answer 4

• Dermatophyte (e.g. Tricophyton rubrum: ringworm + athlete’s foot)

Tx: Topical antifungals (except Tinea Capitis + unguium = Oral)

Question 5

What are some features of a Pityriasis infection and what treatment do they need?

Answer 5

• Malassezia globosa/furfur
• Seborrhoeic dermatitis
• T. versicolor (depigmentation in those with darker skin)

Tx: Antifungal shampoos + topical azoles

Question 6

What are some deep seated infection-causing fungi?

Answer 6

• Candida
• Aspergillus
• Cryptococcus

Question 7

How are deep-seated fungal infections diagnosed?

Answer 7

• Clinical details
• Lab results
• Imaging

Question 8

What are some features of a candida infection, how is it diagnosed and treated?

Answer 8

Deep seated in immunocompromised

Dx:
- Culture
- Mannan
- Abs
- +ve β-D-glucan
- -ve Galactomannan

Tx:
- Candida albicans = fluconazole
- Invasive disease = Amphotericin-B

Question 9

What are some featuers of aspergillus, how is it diagnosed + treated?

Answer 9

Spectrum from allergy to invasion
(ABPA, Invasive Aspergillosis, Aspergilloma)

Dx:
- ELISA
- PCR
- +ve β-Glucan test
- +ve Galastomannan
- Grows on Czapek dox agar

Tx:
- Voriconazole

Question 10

What are some features of cryptococcus, how is it diagnosed + treated?

Answer 10

In immunocompromised (particularly HIV)
- Px: Meningitis with insidious onset in HIV
- A/w: birds (pigeons)

Dx:
- Cryptococcal antigen in serum/CSF
- India ink staining

Tx:
- 3/52 amphotericin B +/- flucytosine