1. Fungal diseases (Mycoses)

2. Learning Objectives
At the end of the lesson, students will be able to:
Discuss how fungi cause diseases
Compare and contrast superficial, cutaneous, subcutaneous, systemic and opportunistic mycoses in terms of characteristics/definition, example of diseases it may cause and its causative agent and laboratory diagnosis

3. How do fungi cause disease?
Growth on body surfaces.
Invasion of the body.
Allergic reactions.
Toxins released after ingestion

4. CLASSIFICATION OF FUNGAL INFECTIONS
Mycoses: fungal diseases.
Tend to be chronic because fungi grow slowly.
Fungal diseases are classified into 4 groups:
Superficial mycoses
Cutaneous mycoses
Subcutaneous mycoses
Deep (systemic) mycoses

5. Example & Causative Agent
Superficial
Cutaneous
Definition
Infection that do not involve a tissue response
Infections of the skin, hair & nails
Example & Causative Agent
Pityriasis: dermatitis characterized by redness of the skin and itching caused by Malassezia furfur
Onychomycoses (Tinea ungium) : nail infections caused by Candida albicans or a dermatophytes
Ringworm(Tinea capitis)
Athlete’s foot(Tinea pedis)
Jock itch(Tinea cruris)
Favus: destruction of the hair follicle caused by Trichophyton schonleini
Lab Diagnosis
Direct Microscopy: 10% KOH is used to digest the skin debris(bottle shaped budding yeast cells)
PCR & other molecular methods
Direct Microscopy: septate branched hyphae
Culture
SDA(Sabourauds dextrose agar medium is used)
Creamy colonies appear
SDA
Honey-combed like thallus(cream colored to yellow brown)

6. Example & Causative Agent
Subcutaneous
Systemic
Definition
Infections beneath the skin
Infections deep within the body
Example & Causative Agent
Sporotrichosis: chronic infection of the subcutaneous tissues and adjacent lymphatics characterized by nodular lesions(Sporothrix schenkii)
Histoplasmosis (Histoplasma capsulatum): Initial infection in lungs. Later spreads through blood to most organs.
Coccidiomycosis (Coccidioides immites): a dimorphic fungus. Resembles tuberculosis
Lab Diagnosis
Direct Microscopy: Tissue sections should be stained using
Grocott's methenamine silver (GMS)
Gram stain
Interpretation: Look for small narrow base budding yeast cells (2-5um).
Clinical material- Skin scrapings, sputum and bronchial washings, cerebrospinal fluid, pleural fluid and blood, bone marrow, urine and tissue biopsies from various visceral organs.
2. Direct Microscopy:
Skin scrapings should be examined using 10% KOH and Parker ink or calcofluor white mounts.
Exudates and body fluids should be centrifuged and the sediment examined using either 10% KOH and Parker ink or calcofluor white mounts.
Tissue sections should be stained using PAS digest, Grocott's methenamine silver (GMS) or Gram stain.
Culture
Sabouraud dextrose agar and Brain heart infusion agar supplemented with 5% sheep blood
SDA

7. FUNGAL DISEASES
Opportunistic mycoses: Caused by organisms that are generally harmless unless individual has weakened defenses:
AIDS and cancer patients
Individuals treated with broad spectrum antibiotics
Very old or very young individuals (newborns).
Examples:
Aspergillosis: Inhalation of Aspergillus spores.
Yeast Infections or Candidiasis: Caused mainly by Candida albicans. Part of normal mouth, esophagus, and vaginal flora.

8. Opportunistic Fungi Mycoses
Candidia albicans
a common unicelluar fungus which is part of the flora of the oral cavity, vagina, and gastrointestinal tract;
They become opportunist especially in immunocompromised people
Oral candidiasis (Oral thrush)
Classic thrush is characterised by a white, curd-like coating on the tongue or elsewhere in the oral cavity. Stomatitis due to Candida is often associated with painful infection of the lips - and corners of the mouth.

9. Genital or perigenital candidiasis ((vulvo vaginitis)
(vulvo)vaginitis due to Candida .
Contamination of the vagina with Candida stems from the endogenous endosaprophytic flora of the gastro- intestinal tract.
Diagnoses
in culture, it grows as blastospores, pseudohyphae, and septate hyphae
candidiasis the collective term for infection involving Candida
cutaneous
vaginal
systemic