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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case Microbiology.

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Presentation on theme: "Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case Microbiology."— Presentation transcript:

1 Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation prepared by Christine L. Case Microbiology B.E Pruitt & Jane J. Stein AN INTRODUCTION EIGHTH EDITION TORTORA FUNKE CASE Eukaryotic Pathogens: Fungi

2 Eukaryotic Pathogens: Fungi What types of eukaryotic organisms are pathogenic, and how do they differ from bacteria? Fungi Classification Hyphae and multicellularity Cell walls: sepatate or coenocytic hyphae Spores: sexual or asexual Unicellular Yeasts Three-Four Major Medically Impt. Groups Zygomycetes: Conjugation Molds Ascomyctes: Sac Fungi Basidomycetes: Club Fungi Fungal Diseases: Mycoses Aspergillosis, histoplasmosis, candidiasis, etc Better Adaptation to Hostile Environments Eukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

3 The Fungi Eukaryotic Aerobic or facultatively anaerobic Chemoheterotrophic Most are decomposers Mildly acidophilic, acid tolerant More osmotically tolerant than bacteria Mycology is the study of fungi

4 Fungi Table 12.1

5 Molds consist of hyphae; a mass of hyphae is a mycelium. Molds Figure hypha Mycelium

6 Key Characteristics: Cell Walls, Spore Types Sometimes hyphal cells are dikaryotic (Aseptate)

7 Types of Spores: Asexual or Sexual Conidiospores (asex.) Ascospores (sexual) Basidospores (sexual) Zygomycota Zygomycota Ascomycota Basidiomycota Ascomycota, Basidiomycota Sporangiospores (asex.) Zygospores (sexual) Sexual spores arise from meiosis Asexual spores arise from mitosis

8 Unicellular fungi, ovid Fission yeasts divide symmetrically Budding yeasts divide asymmetrically Mycoses: Candidiasis (local and systemic) from Candida albicans Beneficial: Saccharomyces cerevesiae/baker’s yeast Yeasts : Single-celled Fungi Figure 12.3

9 Pathogenic dimorphic fungi are yeastlike at 37°C and moldlike at 25°C Dimorphism Figure 12.4

10 Eukaryotic Pathogens: Fungi What types of eukaryotic organisms are pathogenic, and how do they differ from bacteria? Fungi Classification Hyphae and multicellularity Cell walls: sepatate or coenocytic hyphae Spores: sexual or asexual Unicellular Yeasts Three-Four Major Medically Impt. Groups Zygomycetes: Conjugation Molds Ascomyctes: Sac Fungi Basidomycetes: Club Fungi Fungal Diseases: Mycoses Aspergillosis, histoplasmosis, candidiasis, etc Better Adaptation to Hostile Environments Eukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

11 Zygomycete Life Cycle: Conjugation Molds Figure 12.6 Coenocytic hyphae. Produces sporangiospores and zygospores E.g. Rhizopus/black bread mold

12 Ascomycete Life Cycle: The Sac Fungi Septate hyphae. Produces ascospores or conidiospores Systemic mycoses: Aspergillosis, histoplasmosis, penicilliasis Cutaneous mycoses: Microsporum/Trichophyton (jock itch, athlete’s foot, ringworm)

13 Basidiomycete Life Cycle: Club Fungi Figure 12.8 Septate hyphae. Produces basidiospores and sometimes conidiospores. Cryptococcus neoformans (systematic mycosis) Toxic Mushrooms (Amanita)

14 Lichens: Ascomycete with unicellular algae or cyanobacteria Figure 12.10

15 Eukaryotic Pathogens: Fungi What types of eukaryotic organisms are pathogenic, and how do they differ from bacteria? Fungi Classification Hyphae and multicellularity Cell walls: sepatate or coenocytic hyphae Spores: sexual or asexual Unicellular Yeasts Three-Four Major Medically Impt. Groups Zygomycetes: Conjugation Molds Ascomyctes: Sac Fungi Basidomycetes: Club Fungi Fungal Diseases: Mycoses Aspergillosis, histoplasmosis, candidiasis, etc Better Adaptation to Hostile Environments Eukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

16 Aspergillosis (Aspergillus mold) respiratory or systemic Most commonly seen in immunocompromised patients May start in lungs as fungus ball or in sinuses Can become systemic (esp. in AIDS); endocarditis (valves) Bronchiectasis (scarring of bronchioles) Prefers aerobic environment Asthmatics may be allergic to mold spores Found in dead and decomposing plant material in nature Treated with amphotericin B; allergics with prednisone Ascomycete

17 Candidiasis caused by Candida albicans yeast Vaginitis (“vaginal yeast infection”) Thrush Systemic candidiasis, often in AIDS patients Treated with antifungals like nystatin Ascomycete

18 Histoplasmosis (Histoplasma capsulatum) Dimorphic: both yeast-like and mold-like Mild respiratory infection Acquired from airborne spores often in bird and bat feces Mostly immunocompromised patients; AIDS Often not treated, otherwise with amphotericin B Ascomycete

19 Pneumocystis pneumonia (Pneumocystis jurovecii) Yeast-like and protozoan-like Hard to culture and classify Pathogenic in immunosuppressed individuals (e.g. AIDS) Forms cysts in the lungs that rupture to release more cells Causes pneumonia Human-based organism only In its own group: Deuteromycota

20 Skin mycoses Tinea pedis (athlete’s foot) Tinea corporis or capitis (ringworm) Tinea cruris (jock itch) Usually caused by Trichophyton, Microsporum, or Epidermophyton Microsporum Epidermophyton All are ascomycetes

21 Eukaryotic Pathogens: Fungi What types of eukaryotic organisms are pathogenic, and how do they differ from bacteria? Fungi Classification Hyphae and multicellularity Cell walls: sepatate or coenocytic hyphae Spores: sexual or asexual Unicellular Yeasts Three-Four Major Medically Impt. Groups Zygomycetes: Conjugation Molds Ascomyctes: Sac Fungi Basidomycetes: Club Fungi Fungal Diseases: Mycoses Aspergillosis, histoplasmosis, candidiasis, etc Better Adaptation to Hostile Environments Eukaryotic pathogens are mostly parasitic and are difficult to target selectively with drugs since their cells are so similar to human cells.

22 Fungi vs Bacteria Sugar or salt tolerance More tolerant of high osmotic environments Less tolerant of high osmotic envir. (grows more easily on jams and jellies) Acid tolerance More tolerant of acidic environments Less tolerant of acidic environments (can culture on Sabourad agar) Moisture toleranceTolerant of low moisture environments Requiring higher moisture environments (can grow on shoe leather!) Nitrogen requirementsRequire less nitrogen Require more nitrogen Carbohydrate produceProduces indigestible carbohydrates Most carbohydrates produced are digestible Can digest plant carbohydrates Can’t digest some plant carbos. (Mycosterols), genatmycin


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