The document provides information on medical mycology and characteristics of fungi. It discusses that fungi are studied in mycology and have characteristics such as hyphae, yeasts, dimorphism, and spores. It then summarizes several medically important fungi that can cause diseases, including dermatophytes that cause cutaneous mycoses, dimorphic fungi that cause systemic mycoses, and opportunistic fungi like Candida and Aspergillus. The document emphasizes the importance of understanding fungi and the diseases they can cause in humans.

1. MEDICAL
MYCOLOGY
Phan Chia Wei (PhD)
Department of Pharmaceutical Life Sciences
Faculty of Pharmacy
phancw@um.edu.my

2. Armillaria solidipes
Mirror mirror on the wall, who’s the largest of them all?

5. The international acceptance of the recognition of the macroscopic organisms of Earth as Fauna,
Flora, and Funga paves the way for substantial changes in educational and agricultural policies,
amongst others. This will facilitate the incorporation of mycology in matters of national interest, such
as conservation, habitat protection, species protection, and education.

6. Pathogenic Eukaryotes
• The study of fungi is called mycology
• Fungi are in the Fungi kingdom. Fungi are chemo-
heterotrophs and acquire food by absorption.
• With the exception of yeasts, fungi are multicellular.
• Most reproduce with sexual and asexual spores.

7. Characteristics of
Fungi
• Vegetative structure- fungal colonies;
composed of the cells involved in
catabolism and growth
• Thallus – body of a mold and fleshy
fungi
• Long filaments of cells joined together;
these filaments are called hyphae

8. Characteristics of
Fungi
• Septate hyphae → contained one nucleus
• Coenocytic hyphae → no septa
• Vegetative hypha → hypha that obtains
nutrients
• Reproductive or aerial hypha →
reproduction
• Hyphae grow to form a filamentous mass
called a mycelium, which is visible to the
unaided eye

9. a) Septate hyphae have cross walls, or septa, dividing the hyphae into
cell-like units. (b) Coenocytic hyphae lack septa. (c) Hyphae grow by
elongating at the tips.

10. Aerial and
vegetative hyphae
• A colony of Aspergillus niger
grown on a glucose agar plate,
showing both vegetative and
aerial hyphae.
• Aerial hyphae, showing
reproductive spores.

11. Characteristics of Fungi
• Yeast- non-filamentous, unicellular fungi that
are typically spherical or oval.
• Budding- produce up to 24 daughter cells by
budding
• Pseudo-hypha- buds that fail to detach
themselves
• Candida albicans attaches to human
epithelial cells as a yeast but usually requires
pseudo-hyphae to invade deeper tissues

12. Characteristics of
Fungi
• Facultative anaerobic growth
• Saccharomyces species produce ethanol
in brewed beverages and carbon dioxide
for leavening bread dough
• Dimorphism-pathogenic species-two
forms of growth; as a mold or as a yeast
(Histoplasma capsulatum) -
histoplasmosis

13. Characteristic of
Fungi
• A micrograph of Saccharomyces
cerevisiae in various stages of budding.
• Candida albicans. Notice the spherical
chlamydoconidia (resting bodies
formed from hyphal cells) and the
smaller blastoconidia (asexual spores
produced by budding)

14. Fungal
Dimorphism
• Dimorphic fungi are fungi that can
switch between yeast and mold,
depending upon the environmental
conditions.
• Fungal dimorphism (Mucor indicus)

15. Medically Important Fungi
• Zygomycota
• conjugation fungi, saprophytic molds
• Rhizopus stolonifer
• Microsporidia
• obligate intracellular parasites; lacks
mitochondria
• chronic diarrhea and keratoconjunctivitis
most notably in AIDS patients
• Encephalitozoon in pet rabbit (eye)

17. Medically
Important Fungi
• Ascomycota
• sac fungi; Talaromyces;
Penicillium

18. Medically
Important Fungi
• Basidiomycota
• produce mushrooms

19. Fungal
Toxins
and
Allergies
• Mycotoxicoses (toxins)
• Allergies (to fungal spores)

20. Fungal Toxins and Allergies
• Mycotoxicosis
• Amanita mushrooms
• Toxins- amanitin and phalloidin (hepatoxins)
• Amanitin- inhibits cellular RNA synthesis
• Ergotism- caused by mold Claviceps – caused vascular and neurologic effects
• Aflatoxins- coumarin derivatives produced by Aspergillus flavus - liver damage and tumors

21. Antifungal drugs
• Antifungal drugs
• Amphotericin B- binds to
ergosterol and disrupts fungal cell
membranes
• Fluconazole- inhibits ergosterol
synthesis

22. Fungal Diseases
• Any fungal infection is called a mycosis
• Five groups according to the degree of tissue involvement and mode of
entry into the host:
1. Systemic
2. Subcutaneous
3. Cutaneous
4. Superficial
5. Opportunistic

23. Cutaneous &
Subcutaneous
Mycoses
Superficial and cutaneous mycoses
are among the most common of
all communicable diseases

24. • Tinea pedis (foot)
• Tinea unguium (nails)
• Tinea manuum (hand)
• Tinea cruris (groin)
• Tinea corporis (body)
• Tinea capitis (scalp)
• Tinea faciei (face)
• Tinea barbae (beard)
• Tinea imbricata (overlapping pattern)
• Tinea nigra (black)
• Tinea versicolor (various colors)
Malassezia furfur

25. Cutaneous & Subcutaneous
Mycoses
• Caused by fungi (dermatophytes)
• Infect superficial keratinized structures (skin, hair, and
nails)
• Three genera:
• Trichophyton
• Epidermophyton
• Microsporum

26. Cutaneous & Subcutaneous Mycoses
• Tinea versicolor- caused by Malassezia
furfur
• Hypopigmented area
• Fluconazole
• Azoles are synthetic antifungals
with broad-spectrum fungistatic
activity against fungi
• Azoles disrupt the synthesis of
ergosterol, which is the principal
sterol in fungal cell membranes

27. Cutaneous & Subcutaneous Mycoses
• Tinea pedis (athlete’s foot)
• Peeling and cracking of the skin in toe
webs
• Itraconazole and terbinafine
• Terbinafine (allylamine antifungal) has a
fungicidal effect by inhibiting the
enzyme squalene monooxygenase which
is involved in the synthesis of sterol in
fungi. This inhibits fungal ergosterol
biosynthesis by decreasing ergosterol
levels.

28. Cutaneous &
Subcutaneous Mycoses
• Subcutaneous mycoses
• Sporotrichosis (rose gardener’s disease) -
Sporothrix schenckii
• Dimorphic fungus
• Mold form in plants, yeast form in human
• Gardener and farmer
• Itraconazole

29. Cutaneous &
Subcutaneous Mycoses
• Budding yeast cells of Sporothrix
schenckii, stained black

30. Systemic Mycoses
• Coccidioidomycosis, histoplasmosis, blastomycosis, and
paracoccidioidomycosis
• Coccidioidomycosis (valley fever) is caused by Coccidioides posadasii or C
immitis.
• Inhalation of arthroconidia leads to a primary infection that is
asymptomatic in 60% of individuals
• The other 40% of individuals develop fever (valley fever)
• Itraconazole

32. Systemic Mycoses
• Chest radiograph of a patient with
coccidioidomycosis revealing enlarged
hilar lymph nodes and a cavity in the left
lung.

33. Systemic Mycoses
• Histoplasmosis- superficially resembles
tuberculosis
• Histoplasma capsulatum – dimorphic
• Limited geographic range in the United States
• Droppings from birds and bats
• Humans acquire the disease from airborne
conidia
• Amphotericin B or itraconazole.

34. Systemic Mycoses
• Yeast like Histoplasma
capsulatum
• In soil or artificial media, it forms
a filamentous mycelium carrying
reproductive conidia

35. Opportunistic Mycoses
• Yeast genus Candida are capable of causing candidiasis.
• They are members of the normal flora of the skin, mucous membranes, and
gastrointestinal tract
• C. albicans, C. parapsilosis, C. glabrata, C. tropicalis, C. guilliermondii, and C.
dubliniensis
• The widespread use of fluconazole has precipitated the emergence of more azole-
resistant species, such as C. krusei and C. lusitaniae.
• The risk factors associated with superficial candidiasis include AIDS, pregnancy, and
diabetes

36. Opportunistic Mycoses
• Yeast invasion of the vaginal mucosa leads to vulvovaginitis.
• Thrush can occur on the tongue, lips, gums, or palate.
• Candidal invasion of the nails and around the nail plate
causes onychomycosis.
• Topical nystatin or oral ketoconazole or fluconazole;
amphotericin B

39. Opportunistic Mycoses
• Cryptococcus neoformans and C.gattii
are environmental, basidiomycetous
yeasts.
• Yeast cells possess large
polysaccharide capsules
• Pigeon feces
• India Ink preparation

40. Opportunistic Mycoses
• Capsule
• Cryptococcus neoformans

41. • The yeasts may multiply and
disseminate to other parts of the
body but preferentially to the
central nervous system, causing
cryptococcal meningoencephalitis

42. Opportunistic Mycoses
• Aspergillosis
• Aspergillus species- exist only as molds; not dimorphic
• Septate hyphae that form V-shaped (dichotomous) branches
• Conidia of Aspergillus form radiating chains; Mucor and Rhizopus-
enclosed within sporangium
• Mucormycosis- diabetic patients- mold spores in the sinuses form
hyphae that invade blood vessels that supply the brain

43. Opportunistic
Mycoses
• Many people recovering from COVID-19
have of late been afflicted by black
fungus – or mucormycosis – disease.
• The fungus invades the sinus and makes
its way into the intraorbital and
intracranial regions. If its progression is
not checked early, 50-80% of patients
could die.

44. The end
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