1. PHARMACEUTICAL MICROBIOLOGY I PHT 226
Dr. Rasheeda Hamid Abdalla
Assistant Professor

2. GENERAL PROPERTIES
OF FUNGI

3. OBJECTIES Fungal Infection Pathogenic Fungi Characteristic structures
Habitat and Nutrition
Modes of Fungal Growth
Sporulation

4. Fungi
The fungi are a diverse group of saprophytic and parasitic eukaryotic organisms
Fungi can be distinguished from other infectious organisms such as bacteria or viruses because they are eukaryotes (they have membrane –enclosed nucleus).

5. Kingdom:Mycota
-Of the some 100,000 fungal species only about 100 have pathogenic potential to humans
Human fungal diseases (Mycoses)
are classified by the location or in the body where the infection occurs:

6. Fungal Infection
Cutaneous : when the infection limited to the epidermis
Subcutaneous when the infection penetrates significantly beneath the skin
Systemic when the infection is deep within the body or disseminated to internal organs

7. Fungal Infection Systemic mycoses can be divided into:
Caused by true pathogenic fungi capable of infecting healthy individuals
Opportunistic ,infecting primarily individuals who have predisposing conditions such as
-immunodeficiency or
-debilitating diseases (diabetes ,leukemia , etc.)

8. Fungi produce and secrete a variety of unusual metabolic products, some of which when ingested, are highly toxic to humans and animals . Thus fungi can cause poisoning as well as infections
Fungal spores are important as human allergenic agents

9. Pathogenic Fungi 1-True pathogen: A-cutaneous infective agents
Epidermophyton species
Microsporum species
Trichophyton species
B-Subcutaneous infective agents
Actinomadura madurae
Cladosporium
Madurella grisea
Phialophora
Sporothrix schenckii

10. Pathogenic Fungi C-Systemic infective agents Blastomyces dermatitidis
Coccidioides immitis
Histoplasma capsulatum
Paracoccidioides brasiliensis

11. Pathogenic Fungi 2-Opportunistic pathogens Absidia corymbifera
Aspergillus fumigatus
Candida albicans
Cryptococcus neoformans
Pneumocystis jirovecii

12. Categorization of fungi
Categorization of fungi depend on:
Characteristic structures
Habitats
Mode of growth
Reproduction

13. Characteristic structures
Cell wall and membrane components:
It composed largely of chitin, a polymer of N- acetylglucosamine, rather than peptidoglycan which is the characteristic component of bacterial cell walls
Fungi are therefore unaffected by antibiotics (penicillin) that inhibit peptidoglycan synthesis

14. Characteristic structures
The fungal membrane contains ergosterol rather than the cholesterol found in mammalian membranes.
These chemical characteristics are useful in targeting chemotherapeutic agent against fungal infections.

15. Mechanism of Action of Antifungal
Amphotericin B and Nystatin bind to ergosterol present in cell membranes of fungal cells .there they form pores that disrupt membrane function , resulting in cell death.
The imidazole antifungal drugs (clotrimazole, ketoconazole , miconazole)
and triazole antifungal agents (fluconazole and itraconazole)interact with C-14α-demethylase to block demethylation of lanosterol to ergosterol
Ergosterol is a vital component of the cell membrane of fungi ,and disruption in it is biosynthesis result in cell death.

16. Habitat and Nutrition
All fungi are heterotrophs (they require some performed organic carbon source for growth)
They depend upon transport of soluble nutrients across their cell membranes
-To obtain these soluble nutrients ,fungi secrete degradative enzymes (for example, cellulose, proteases, nucleases ,etc) into their immediate environment .

17. -This ability that enables fungi to live saprophytically on organic waste
The natural habitat of almost all fungi is soil or water containing decaying organic matter

18. Fungal Growth Most fungi exist in one or two basic morphologic forms:
Filamentous mold
Unicellular yeast
However, some fungi are dimorphic (that is ,they switch between these two forms in response to environmental conditions)

19. Filamentous (mold-like) fungi
The vegetative body , or thallus , of the mold –like fungi is typically a mass of threads with many branches, resembling a cotton ball
This mass is called a mycelium , which grows by branching and tip elongation.

20. The thread called hyphae ,are actually tubular cells that ,in some fungi , are partitioned into segments (septate), whereas in other fungi the hyphae are uninterrupted by cross-wall (non-septate) even in septate fungi

22. Yeast- like fungi
These fungi exist as population of single ,unconnected, spheroid cells
They are some ten times larger than typical bacterial cell
yeast-like fungi reproduce by budding
Some fungal species ,especially those that cause systemic mycoses ,are dimorphic ,being usually yeast-like in one environment and mold –like in another.
Example of conditions that affect the choice of morphology are temperature and carbon dioxide levels

24. Sporulation
Sporulation is the principal means by which fungi reproduce and spread through the environment
Fungal spores are metabolically dormant , protected cells , released by mycelium in enormous numbers
They can be borne by air or water to new sites , where they germinate and establish colonies
Spores can be generated either asexually or sexually

25. THANKS