ppt

2. At the end of the lesson, students will be able to:
1. Discuss how fungi cause diseases
2. 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.  Growth on body surfaces.
 Invasion of the body.
 Allergic reactions.
 Toxins released after ingestion

4. 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. 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
PCR & other molecular
methods
Culture SDA(Sabourauds dextrose agar
medium is used)
Creamy colonies appear
SDA
Honey-combed like
thallus(cream colored to

6. 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

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.  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