Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as well as their dangers, such as toxicity or infection

1. Mohamed Abdullatif Abdurahman
B.Pharm, MMM

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Fungi as Infectious Agents
• Fungi are non-motile eukaryote, widely
distributed in air, dust, fomites and normal flora.
• They have a cell wall composed of complex
carbohydrates such as chitin with glucans and
mannose-proteins.
• Ergosterol is the dominant fungal membrane
sterol.
• Grow as single cells (yeasts) or multi-septate,
branching filamentous cells (hyphae).
• Fungi are relatively nonpathogenic and humans
are relatively resistant.

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5. Structure
1. Hyphae : filamentous cells
of molds
• Septae
• Nonseptate or aseptate
• Dematiaceous (dark
colored) or hyaline
(colorless).
• Mycelia
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6. 2. Yeasts
• These are single-celled fungi,
generally round to oval shaped.
• They reproduce by budding
(blastoconidia).
3. Pseudohyphae :
• Hyphae with sausagelike
constrictions at septations.
• Formed by some yeasts when
they elongate but remain attached
to each other (Candida albicans). 6

7. 4. Thermally dimorphic fungi:
• These are fungi exist in the
from a yeast or yeast-like in
human and filamentous form
in environment (temperature,
nutrient)
• They include the major
pathogens: Blastomyces,
Histoplasma, Coccidioides,
Sporothrix and
Paracoccidioides.
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9. Fungal reproduction
• They reproduce by sexual or asexual
spores.
• Spores morphology may be used in
identification.
Asexual reproduction
• Conidia are asexual spores of filamentous
fungi (molds)
• Blastoconidia are the new yeast ‘‘buds’’
• Arthroconidia are conidia formed by
laying down joints in hyphae followed by
fragmentation of the hyphal strand
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10. • Chlamydoconidium is a thick-
walled spore formed by
rounding and enlargement
within a hyphal segment
• Sporangiospore formed within a
sporangium, or sac, at the end
of an aerial hypha called a
sporangiophore.
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11. Sexual reproduction.
• In this process, opposite
mating types come together
and fuse.
• A visible fruiting body often
results and it is the location of
the haploid spores.
• The most recognized fruiting
body from which spores are
produced is the mushroom.
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13. Fungal nutrition
• Fungi usually grow better in an environment with a
pH5.
• Almost all molds are aerobic. Most yeasts are
facultative anaerobes.
• Most fungi are more resistant to osmotic pressure than
bacteria.
• Fungi can grow on substances with a very low
moisture content, generally too low to support the
growth of bacteria.
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14. • Fungi require preformed organic compounds derived
from their environment.
1. Saprobes: live on dead organic material. Some are
opportunistic.
2. Commensal colonizers: generally live in harmony on
humans, deriving their nutrition from compounds on
body surfaces. Some are opportunistic.
3. Pathogens: infect the healthy but cause more severe
disease in the compromised hosts. The damage to living
cells provides nutrition. Most of these are also
environmental saprobes.
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15. Fungal disease
1. Fungal allergies : due to spores and volatile fungal
metabolites (sick building syndrome and farmer’s
lung).
2. Mycotoxicoses : ingestion of fungal-contaminated
foods (e.g., ergot-contaminated bread or aflatoxin
contaminated peanuts).
3. Fungal infections (mycoses)
– True pathogens: Systemic, Subcutaneous, Cutaneous, and
Superficial Mycoses
– Opportunistic mycoses: Increasing prevalence due to
increased use of antibiotics, corticosteroids, and cytotoxic
drugs.
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Pathogenesis of the Fungi
• Portal of entry
– Cutaneous and superficial – contamination of skin
surface
– Subcutaneous - inoculated skin; trauma
– Systemic mycoses – respiratory portal; inhaled
spores
• Virulence factors – thermal dimorphism, toxin
production, capsules and adhesion factors,
hydrolytic enzymes, inflammatory stimulants

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Diagnosis of Mycotic Infections
1. Clinical manifestations
2. Microscopic examination
3. Histologic staining
4. Serologic testing
5. Cultures for fungi
6. Fungal antigen detection
7. DNA probes

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Control of Mycotic Infections
• Immunization is not usually effective.
• Control involves intravenous, oral and
topical antifungal.
• In some cases surgical removal of damaged
tissues
• Prevention limited to masks and protective
clothing to reduce contact with spores

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23. Concept question?
• The human infection caused by fungi is
called:
A.Mycotoxicosis
B.Mycoses
C.Fungal allergies
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