Clinical Mycology Lec 1.pdf

Lecture (1) Clinical Mycology INTRODUCTION TO MYCOLOGY Dr.Wifag Rabih Objectives To know about important, characteristics of fungi. To know various classifications. To know the medical importance of fungi. To know the treatment of fungal disease. Mycology oMedical Mycology is the study of fungus...

Lecture (1) Clinical Mycology INTRODUCTION TO MYCOLOGY Dr.Wifag Rabih Objectives To know about important, characteristics of fungi. To know various classifications. To know the medical importance of fungi. To know the treatment of fungal disease. Mycology oMedical Mycology is the study of fungus organisms that cause disease in humans. oMyco = fungus logy = study ◦ What is fungi? Fungi are a group of simple organisms that have no Chlorophyll Lack of Chlorophyll profoundly affects the lifestyle of fungi. Not dependent on light Some kinds of fungi live on land and other types of fungi live in water environments What is a fungus? Firstly, One of the original kingdoms; on a par with animals and plants. Fungi are NOT plants. Eukaryotic (nuclear membranes, organelles). Larger, and more complex than bacteria. Has a cell wall composed of (CHITIN). Reproduce by spores. a sexually and sexually in many species. Widespread in nature. Most species are harmless, some are used as food, recycling of dead organic matter, and drug industry. Fungi absorb their food, rather than ingesting it. 1. Fungi grow better at a pH of 5, which is too acidic for most bacteria. 2. Almost all molds are aerobic, most yeasts are facultative anaerobes. 3. Fungi are resistant to high osmotic pressure. 4. Fungi can grow with very low moisture. 5. Fungi require less nitrogen than bacteria to grow. 6. Fungi can break down complex carbohydrates (wood, paper), that most bacteria cannot. Classification of fungi By morphology 1/Yeasts ◦ Single-celled ◦ Elongate, to form chains of cells (pseudohyphae) ◦ Reproduce a sexually by budding to form daughter cells or blastospores. Classification of fungi 2/ Molds, (moulds) ◦ Multicellular ◦ Fungi are made up of filaments that are stacked together from end to end. ◦ Form tubular structures called (hyphae) which may have cross walls (septate) or lack cross walls (a septate). Many hyphae form a mycelium. Reproduce sexually by spore and hyphae. Classification of fungi 3/ Dimorphic fungi. Fungi behaving as yeasts or molds ◦ Grow as mold at room temperature(Producing infectious spores). ◦ Grow as yeast at elevated temperature - the form found in the body. ◦ Includes several systemic pathogens. fungal disease A- Mycosis ( Fungal infection) 1. Superficial mycosis-(outer layer skin& hair) 2. Cutaneous mycoses.(deeper in epidermis) 3. Subcutaneous mycoses. (dermis, subcutaneous tissue) 4. Systemic mycoses. (Primary in the lung or spread to another organ) 5.Opportunistic mycoses. B- Fungal Allergies Allergy occurs in fungal spores particularly those of Aspergillus fungus. Example: bronchial asthma. C- Mycotoxicosis Fungal Toxins released after ingestion (mushrooms) e.g.: alpha toxins. fungal infections * Few are pathogenic * Diseases are not life-threatening except in immunocompromised patients or several allergic. Common fungal diseases cause: - Discomfort e.g. Candidiasis - Disfigurement e.g. Dermatophyte - Disability e.g. Mycetoma Antifungals Some are fungistatic, while others are fungicidal Structure of fungal cell Antifungals Polyene antibiotic The polyene antibiotics bind with sterols in the fungal cell membrane, principally ergosterol. This causes the cell's contents to leak out and the cell to die. Animal cells contain cholesterol instead of ergosterol so they are much less susceptible. Nystatin: first antibiotic against fungi. Like many other antimycotics and antibiotics, nystatin is of bacterial origin. It was isolated from Streptomyces noursei. Amphotericin B, Natamycin, Rimocidin, Filipin and Pimaricin. Antifungals Imidazole and triazole The imidazole and triazole groups of antifungal drugs inhibit the enzyme cytochrome P450 14α-demethylase. This enzyme converts lanosterol to ergosterol and is required in fungal cell membrane synthesis. These drugs also block steroid synthesis in humans. The triazoles are newer, and are less toxic and more effective: Fluconazole , Itraconazole , Ravuconazole. Imidazoles:Miconazole ,Ketoconazole,Clotrimazole, Bifonazole. Antifungals Allylamines Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis: Terbinafine - marketed as Lamisil, Amorolfine, and Naftifine. Echinocandin Echinocandins inhibit the synthesis of glucan in the cell wall, probably via the enzyme 1,3-β glucan synthase: Anidulafungin , Caspofungin, Micafungin. Antifungals Flucytosine is an anti-metabolite. Griseofulvin binds to polymerized microtubules and inhibits fungal mitosis; It is derived from the mold Penicillium griseofulvin Antifungals References Tortora, G. J., B. R. Funke, and C.L. Case. Microbiology, An Introduction, (7th edition). Benjamin Cummings, San Francisco,. Patrick R.M., Michael A. P.,& Ken S. Medical Micrbiology, (5th.ed.) Mosby ISBN13:97803230033039 http://en.wikipedia.org/wiki/Antifungal http://www.lamisil.com/ http://www.tinactin.com/ http://en.wikipedia.org/wiki/Griseofulvin http://www.journals.uchicago.edu/CID/journal/issues/v30n4/990666/990666.text.html?erFrom=4860378516935905751Guest http://www.mycology.adelaide.edu.au/downloads/antifungals.pdf#search=%22antifungal%20drugs %22 http://en.wikipedia.org/wiki/Nystatin http://inventors.about.com/library/inventors/blnystatin. THANK YOU