Fungus infections:
Category Comment
Organisms type eukaryotic organisms
Environment type aerobes & facultative Never strict
anaerobes anaerobes.
Place living Soil, water & air (Most of Except Candida
fungus) albicans which is
part of human normal
flora
Uses of Fungus 1- Fermentation (bread,
wine, soya sauce)
2- Producing antibiotics
(Penicillin)
3- Medicinal Mushrooms
Fungus harms 1-cause human disease
(Mycosis)
2-cause damage to food&
fabric
3- plant diseases (major
cause)
Fungul organisms 1- Molds e.g. Aspergillus Molds are:
2- Yeast Multicellular
3- Dimorphic fungi Has Long filament (hyphae)
e.g. Histoplasma Mass of hyphae (mycelium)
Dimorphic fungi can be:
1-Yeast at 37 C (in living
organism)
2- Molds at 25 C
Reproduction Asexual spores A: Blastoconidia and
pseudohyphae(Candida).
B: Chlamydospores
(Candida).
C: Arthrospores
(Coccidiodes).
D: Sporangia and
sporangiospores (Mucor).
E:Microconidia
(Aspergillus).
F: Microconidia and
macroconidia
(Microsporum).
Morphological forms 1.hyphae: individual thread
(septate or nonsepetate)
2. Mycelium: A mat
of thin, tangled
threads
3. yeast form (budding)
4. pseudo mycelium
Fungus diseases Most are not A risk factor is the level of
communicability communicable hand-hygiene of healthcare
except Dermatophyte workers.
infections
(ringworm) and Vaginal candidiasis: male
Candidiasis partners are mostly
asymptomatic – Exact
reservoir unknown but
considered to be human to
human via droplet aerosol.
LABORATORY Direct microscopic
DIAGNOSIS examination
Culture of the
organism
DNA probe tests
Serologic tests.
Treatment Antifungal: different
classes.
Surgery: sometimes
necessary.
Modification of risk
factors.
Clean environment.
Fungi structure components:
Definite nucleus enclosed by a nuclear
membrane (contains
DNA & RNA)
Ribosome similar to humans
Fungal cell membrane
Fungal cell wall Consist primarily of:
Chitin: not peptidoglycan
It is a polysaccharide (long
chains of N-
acetylglucosamine)
And contains other
polysaccharides:
β-glucan: long polymer of d-
glucose and it is the site of
action of the antifungal drug
caspofungin
Ergosterol Functions:
1. Protects cytoplasm
2. Regulates the intake &
secretion of nutrients
3. Facilitates capsule and cell
wall synthesis
Fungi are insensitive to certain antibiotics:
Penicillins
Cephalosporins
Because it inhibit peptidoglycan synthesis
Classification of medical mycoses:
cutaneous subcutaneous systemic opportunistic
Other name Dermatophytoses Sporotrichosis
(tinea, ringworm)
Type& Chronic 1.Caused by fungi (in Caused spores 1.
cause of infections soil and vegetation) of dimorphic fungi Cryptococcus
infection that have neoformans
2. caused by spores of their mold forms in 2. Candida spp
mold the soil 3.
Aspergillus spp
Require a
compromised host li
(cancer, organ
transplantation,
surgery, and AIDS)
to cause infection
Occurrence Warm& humid 1.introduced Introduced to internal
area areas of the body into organs by inhalation
subcutaneous of spores
tissue
through trauma.
2. introduced into the
skin by a thorn
Terminology According
to the
affected
body part
Tinea + site of
infection
Appearance Ringworm: Causes a local
inflamed circular pustule or ulcer
border containing with nodules
papules and along the
vesicles draining
surrounding a lymphatics.
clear area of
relatively normal
skin.
Tinea: Red, scaly,
rash, with central
clearing &
migrating
margins
Examples of 1. Tinea Corporis 1.
diseases (body) Histoplasmosis
2. Tinea capitus:
(scalp & hair)
3. Tinea cruris 2. lung infections:
(perineum) asymptomatic and
self-limited
4. Tinea pedis
(athletes foot)
5. Tinea ungium
(nail)
6. Tinea barbae(
beard&
moustache)
Disease name causes Symptomps/ comments Treatmen
appearance
Tinea Malassezia Appear as occurs more frequently in Treatmen
Versicolor furfur hypopigmented hot, humid weather topical m
areas and have a tendency to
recur
skin discoloration
Tinea Nigra Cladosporium brownish spot It infect the
werneckii caused by keratinized layers
(in soil the melanin-like of the skin.
and transfer pigment in the hyphae.
during injury)
opportunistic Candida Blood cultures Infection
mycoses albicans. grew budding yeasts Inside
(a member of the that formed germ the eye
enters normal flora tubes.
through a break in way of diagnosis
the skin) or test:
Appear like budding -Germ tube test (3h at
cells 37°C)
Observation: hyphae
emerging from a yeast-like
structure
- Gram stain
Appear like Pseudohyphae:
Chains of elongated
budding cells
or
budding cells (Spherical to
oval)
Mucosal Predisposing White adherent
infections factors: patches on buccal
Obesity mucosa or vagina.
DM
Use of steroids
Used of
Antimicrobials
Chemotherapy
HIV
immunosuppressant
Cutaneous - yeast (fungus) Erythematous
candida intertrigo Candida plaques with Occurrences area in
- fine erosions & (intertriginous areas):
satellite Axilla, inguinal
nodules folds,
inflammamary area,
web space of
toes/fingers
Aspergillosis Aspergillus fever, cough, difficulty Risk factor:
Fumigatus breathing Defect in neutrophil •
Most neutropenia due to •
frequently cytotoxic
involves the
lungs and chemotherapy •
paranasal
sinuses. systemic •
corticosteroids
Can spread from the
lungs to the brain,
kidneys, liver, heart,
and bones
How can discover the candida albicans ?
- cultivated on Sabouraud Dextrose Agar (SDA) - 72 hours at 37°C
- additional cultivation 24 hours at room temperature
Appearance of candida:
Cream to white, flat or domed with a dry or waxy surface
