Intro to clinical mycology

Question 1

Fungal diseases

Answer 1

Many fungal pathogens can rapidly form bio films in the human body: non-renewing surfaces, cavities
Bio films are organised microbial communities that are innately resistant to antimicrobial’s and host immune mechanisms
They are a major source of disseminated infections
Bio film infections can’t be treated with antimicrobials alone.

Question 2

How do we classify fungi/fungal diseases?

Answer 2

1. Superficial mycoses - Trichophyton spp. and other dermatophytes, Candida spp. Malassezia spp.
2. Subcutaneous mycoses - sporotrichosis phaeohyphomycosis
3. Deep mycoses caused by opportunistic pathogens - aspergillosis, candidosis, pneumocytosis
4. Systemic mycoses caused by opportunistic infections - aspergillosis, candidosis
5. Systemic mycoses caused by primary pathogens - blastomycoses, histoplasmosis,

Question 3

1. Superficial mycoses

Answer 3

Tinea corporis, Tinea cruris, Tinea pedis, Onychomycosis
Seborrhoeic dermatitis, dandruff
Candida colonization: C. albicans in mouth and intestine, C. parapsilosis in shoulder
Candida vulvovaginitis (women of child bearing age)
Acute oral candidosis
Chronic oral candidosis
Cutaneous candidosis

Question 4

2. Subcutaneous mycoses

Answer 4

Subcutaneous zygomycosis: causes

• Basidiobolomycosis - found in decaying plants, fruit bats, animal faeces
• Rhinofacial conidiobolomycosis - found in tropical rain forests, in rotting veg

Question 5

3. Deep mycoses caused by opportunistic pathogens

Answer 5

Fungal sinusitis
Fungal ball
chronic pulmonary aspergillosis

Question 6

4. Systemic mycoses caused by opportunistic infections

Answer 6

Candida:
- Most common systemic mycosis, incidence increasing
- Mortality 40%
- C. albicans most common species
- Almost always seen in patients with risk factors: CVC, GI surgery, immunosuppression, malignancy (esp. haematological)
Involvement of other organs:
- Arthritis,Osteomyltis, Endocarditis, Meningitis, Renal tract, Eye
Early treatment of candidaemia critical to good outcome
Aspergillus spp:
Cause a number of types of disease -
- Allergic bronchopulmonary aspergillosis, Chronic pulmonary aspergillosis, Aspergilloma, Invasive aspergillosis (pulmonary), Rhino sinusitis, Burns infections
Invasive aspergillosis in severely immunocompromised patients
Musicologists
Risk factors: diabetes, severe immunosuppression,
prolonged neutropaenia, trauma, iron overload
• Disease: rhino cerebral, pulmonary, cutaneous,
gastrointestinal, CNS

Question 7

5. Systemic mycoses caused by primary pathogens

Answer 7

Dimorphic endemic pathogens
- Coccidioides immitis/posadasii
- Histoplasma capsulatum
- Blastomyces dermatidis
- Paracoccidioides brasiliensis
Exist in mold form in the environment (soil) but grow as a yeast at body temperature (37°C)
Acquired through contact with nature via inhalation
Clinical outcome depends on the immune status of the host

Question 8

Antifungals vs Antibacterials

Answer 8

Agents available:
• Azoles	
• Polyenes
• Echinocandins
• Terbenafine
• Flucytocine
• Miscellaneous