INTRODUCTION TO MYCOLOGY Human pathogens
Cause spoilage of certain foods
Case Study
Used in the production of bread, cheese, wine and
an 18yo/male went to his doctor due to a 1-week beer.
history of pruritus on his back and occasionally on his chest.
He noted some “white” patches on his skin. This started after
getting himself to a swimming party in a public pool.
Furthermore, he admitted that he is a “sweaty’ type of person
especially during summer. And that he was “sickly” these past
few weeks. No other co-morbidities noted, rest of his medical
histories were U/R.
On PE, there were hypopigmented finely scaly
macules and patches on his back and chest. No other
significant lesions were noted in other parts of his body. Other
Organ systems were Normal.
Tinea
versicolor- Malassezia furfur
General Characteristics
Eukaryotic cells
Lack chlorophyll 🡪 does not photosynthesize.
Obligate aerobes or facultative anaerobes
Heterotrophs
Require a preformed organic source of carbon
🡪ENERGY.
Natural habitat: Environment
- Exception: Candida albicans (normal human
flora)
Principal Decomposers
Differs from other eukaryotes: CHITIN in their Cell
walls.
Fungal Morphology
Cell wall – chitin; surrounds the cell membrane.
- carbohydrates and protein.
- potent antigens
Cell membrane – bilayered
- contains ERGOSTEROL.
Capsule – polysaccharide coating surrounds the cell
wall. Protection against phagocytosis
- stained with India ink stain.
Hypha – Basic Structural unit
Mycelium – Aggregates of Hypha
Grow in warm, humid, damp, low saline 2 Forms of hypha
environments.
1. Septate hypha – with crosswalks/partitions
2. Aseptate Hypha – continuous
- Ex: Zygomycetes, Rizous, Mucor
Parts of Fungi
2 phases/types
A. MOLD phase – cottony mycelial mass
- grows on Room Temperature Reproduction of Fungi
- occurs in filaments/ hyphae.
SEXUALLY or ASEXUALLY
- Sexual Reproduction – Fungi Imperfecti
- Asexual Reproduction – Perfect Fungi
Asexual Reproduction
Through BUDDING/FRAGMENTATION/FISSION
B. YEAST Phase – creamy colonies resembling
Undergoes MITOSIS
bacterial colonies
Spores are asexually produced from mycelium.
- grows at 37C
Asexual Spores
- consist with solitary cells produce by budding
1. Sporangiospores – enclosed in Sporangium
(Ex. Rhizopus sp., Mucor sp)
2. Conidiospores – at the end of the hyphae
(Ex. Aspergillus, Penicillum)
3. Chlamydiospore – in between hyphae (Ex.
Candida sp)
4. Arthrospores – fragmentation of hyphae (Ex.
Trichosporon)
5. Blastospores – budding (Ex. Candida
albicans)
2 forms
1. Monomorphic – Mold / yeast
2. Dimorphic – capable of 2 growths: Mold to Yeast/
Yeast to Mold
Sexual
Reproduction
Involves mating/sexual cycle (fusion of 2 hyphae
with their nuclei)
Undergoes MEIOSIS
2 mating systems:
- HETEROTHALLIC – requires other
(vid)
individual thallus
- HOMOTHALLIC – have the ability to self- 3. Periodic Acid Shiff – in fungi, Magenta
fertile color
Uses Specialized spore-forming structures for 4. Lactophenol cotton blue – blue discoloration
reproduction: of CW
1. Ascospores – they are enclosed in Ascus/asci
2. Zygospores – fusion of 2 gametes / haploid
nuclei (ex. Zygomycetes)
3. Oospore - forms when an oogonium (female
gamete) is fertilized by an antheridial (male
gamete) nucleus (ex. Oomycota)
4. Basidiospore – enclosed in a club-shaped
Basidium (ex. Basidiomycetes)
B. Culture
1. Saboraud Dextrose Agar – General isolation
2. Mycosel/Mycobiotic - SDA +
Cycloheximide and chloramphenicol
3. Cornmeal Agar -studying mycelium or
pseudomycelium formation, and for the
study of Candida species.
4. Birdseed agar - used for selective isolation
and differentiation of Cryptococcus
neoformans from other.Cryptococcus and
other yeasts
Clinical Diseases 5. Cottonseed agar – used to convert
Blastomyces mold to yeast phase.
C. Biochemical Test
1. Germ Tube test - outgrowth produced by
spores of spore- releasing fungi during
germination.
- sample is suspended in a serum then
examined under microscopy for the presence
of Germ Tube
Mode of Infection
Inhalation of spores or inoculation by trauma into the
skin/ direct contact / too much or unnecessary taking
antibiotic. 2. Urease Test - Cryptococcus neoformans,
Coccidioides immitis, Histoplasma
Laboratory diagnosis capsulatum, Sporothrix schenckii,
A. Microscopic Trichosporon, Aspergillus.
3. Hair Perforation Test – use to differentiates
1. KOH mount (10%) – dissolves keratin Dermatophytes.
2. Staining – India Ink, methenamine silver, Urease Test
calcofluor white
Hair Baiting Test Tinea versicolor- Malassezia furfur
Antifungal Therapy
Polyenes – binds to Ergosterol; Amphotericin B
Azoles – inhibits conversion of lanosterol to
ergosterol; Miconazole.
Allylamines – inhibits epoxidase; Terbinafine.
Echinocandins – inhibits glucan formation;
Caspofungin
Classification
Based on Route of Acquisition
Based on Virulence
Based on Site
BASED ON ACQUISITION
EXOGENEOUS ROUTE- airborne, cutaneous
(trauma/direc inoculation)
ENDOGENUS ROUTE- colonization by normal
flora
- reactivation of previous infection
BASED ON VIRULENCE
PRIMARY INFECTION – direct
infection/establishment of pathogen
OPPORTUNISTIC - causes diseases in
immunocompromised/ weakened immune system
BASED ON SITES
SUPERFICIAL MYCOSES
CUTANEOUS MYCOSES
SUBCUTANEOUS MYCOSES
DEEP/SYSTEMIC MYCOSES
SUPERFICIAL MYCOSES
Affects the superficial layer of the skin
Confined to the Striatum corneum
Does not illicit inflammation
CUTANEOUS MYCOSES SUBCUTANEOUS MYCOSES
involve the integument and its appendages, including infects the subcutaneous tissues usually at the point
hair and nails (stratum corneum or deeper layers of of traumatic inoculation
the epidermis) inflammatory response develops in the subcutaneous
Can illicit inflammation tissue frequently with extension into the epidermis
DERMATOPHYTOSIS
Sporotrichosis- Sporothrix
Dermatophytes: Trichophyton, Microsporum,
Epidermophyton
Tinea corporis- Trichophyton
DEEP/SYSTEMIC MYCOSES
Involves organ systems
Routes: Respiratory Tract, Digestive Tract,
Circulatory system
Histoplasma capsulatum
