Mycology

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Mycology

  1. 1. MYCOLOGY FUNDAMENTALS, DIAGNOSIS AND TREATMENT Dr. Maria Ellery Mendez FPAMS,FPAAM,DPASMAP
  2. 2. <ul><li>General Characteristics: </li></ul><ul><li>> heterotrophs </li></ul><ul><li>> thallopytes </li></ul><ul><li>> chemotrophic organism </li></ul><ul><li>> all are obligate aerobes, some are </li></ul><ul><li>facultative anaerobes </li></ul><ul><li>> all fungi are gram (+) </li></ul><ul><li>> natural habitat is the environment </li></ul>Introduction
  3. 3. Difference between fungi & bacteria Features Fungi Bacteria Nucleus eukaryotic prokaryotic Mitochondria present absent Endoplasmic reticulum present absent Cell membrane sterols cholesterol Cell wall chitin peptidoglycan Spores For reproduction endospores for survival Replication Binary fission/budding Binary fission Ribosomes 80 S 70 S
  4. 4. <ul><li>While all molds are described as aerobic, many </li></ul><ul><li>yeasts are able to grow facultatively </li></ul><ul><li>a. Under anaerobic condition, glucose can be converted </li></ul><ul><li>to alcohol and CO2 via the </li></ul><ul><li>Embden-Meyerhoff pathway </li></ul><ul><li>b. Under aerobic condition, glucose can be oxidized </li></ul><ul><li>completely to CO2 & H2O by some yeast via the </li></ul><ul><li>Citric Acid Cycle </li></ul>
  5. 5. Morphologic Forms of Fungi <ul><li>A. Yeast </li></ul><ul><li>- grow as single cells </li></ul><ul><li>- round to oval in shape </li></ul><ul><li>- are reproduced asexually by the </li></ul><ul><li>process termed as </li></ul><ul><li>1. fission formation </li></ul><ul><li>2. blastoconidia formation (budding) </li></ul>
  6. 6. <ul><li>- grow as long filaments </li></ul><ul><li>1. hyphae </li></ul><ul><li>2. mycelium (mat) </li></ul><ul><li>- mass of hyphae </li></ul><ul><li>a. vegetative </li></ul><ul><li>b. aerial </li></ul><ul><li>The vegetative body or thallus of the mold-like fungi is typically a mass of thread with many branches </li></ul>B. Molds
  7. 7. I. SEXUAL II. ASEXUAL III. PARASEXUAL a. zygospores a.sporangiospores e.g. H.capsulatum Ajellomyces capsulatum b. ascospores b. chlamydospores c.basidiospores c. arthrospores d. blastospores
  8. 8. Reproduction * The sexual (perfect, meiotic ) state is referred to as teleomorph * The asexual (imperfect, mitotic) state of a fungus is termed as anamorph * Many fungi can have both states, especially Ascomycota > Most have either one or the other
  9. 9. <ul><li>> can exist in 2 forms: </li></ul><ul><li>a . tissue phase </li></ul><ul><li>b. mycelial or filamentous phase </li></ul><ul><li>I. Fungal allergies </li></ul><ul><li>II. Mycotoxicosis </li></ul><ul><li>- potent toxins produced </li></ul><ul><li>a. phalloidin c. ergotism </li></ul><ul><li>b. Amanitin d. Aflatoxin </li></ul><ul><li>III. Fungal Infections </li></ul>DIMORPHIC FUNGI FUNGAL DISEASES
  10. 10. LABORATORY DIANOSIS
  11. 11. <ul><li>1.Direct Microscopic examination </li></ul><ul><li>a) Wet preparation </li></ul><ul><li>- uses KOH or NaOH as clearing agent </li></ul><ul><li>b) Calcofluor white stain </li></ul><ul><li>- shows fungal elements in exudats & small skin scales </li></ul><ul><li>under fluorescent microscope </li></ul><ul><li>c) Nigrosin or India Ink </li></ul><ul><li>d) Wright stain or Giemsa stain </li></ul><ul><li>2. Culture </li></ul><ul><li>- slow growers </li></ul><ul><li>- Medium </li></ul><ul><li>Sabouraud Dextrose Agar, Potato Dextros Agar, Blood agar </li></ul><ul><li>Corn Meal Agar </li></ul><ul><li>-IDENTIFICATION OF FUNGUS </li></ul><ul><li>a. Macroscopic examination </li></ul><ul><li>- study the mycotic colony, mycelium & the pigment produced </li></ul><ul><li>b. Microscopic examination </li></ul><ul><li>- uses a drop of LPCB </li></ul><ul><li>-observe the size,shape,septation & color of spores </li></ul>
  12. 12. <ul><li>• IDENTIFICATION OF YEAST CULTURES </li></ul><ul><li>- is based on morphologic characteristics & biochemical tests </li></ul><ul><li>• IDENTIFICATION OF FILAMENTOUS FUNGAL CULTURES </li></ul><ul><li>- uses an immunologic method called exoantigen test </li></ul><ul><li>* antigen extracted are immunodiffused </li></ul><ul><li>against known antisera </li></ul><ul><li>3. Histologic stains </li></ul><ul><li>a. Periodic Acid Shift </li></ul><ul><li>b. Gomori Methenemine Silver Stain </li></ul><ul><li>c. Calcofluor white </li></ul><ul><li>d. Fluorescent Antibody Stain </li></ul><ul><li>- for rapid diagnosis of fungal; cell wall </li></ul>
  13. 13. <ul><li>4. DNA probe test </li></ul><ul><li>- identify colonies growing in culture at an earlier </li></ul><ul><li>stage of growth </li></ul><ul><li>- available for coccidioides, histoplasmas, blastomyces, </li></ul><ul><li>cryptococcus </li></ul><ul><li>5. Immunologic </li></ul><ul><li>- for detection of antigen or antibody </li></ul><ul><li>- complement-fixation ,Agglutination,Precipitin test </li></ul><ul><li>- useful only for systemic & opportunistic mycoses </li></ul><ul><li>* C-F is freq. used in suspected cases of </li></ul><ul><li>coccidiodomycoses, blastomycoses, histoplasmosis </li></ul><ul><li>6. Wood’s light </li></ul><ul><li>-use in determining the prognosis of the patient </li></ul><ul><li>-e.g. T.capitis-yellowish green in color </li></ul><ul><li>P. versicolor-golden yellow </li></ul>
  14. 14. ANTIFUNGAL AGENTS <ul><li>- MOA: combines sterol in cell membrane causing disruption </li></ul><ul><li>& leakage of the cytoplasmic contents </li></ul><ul><li>- E.g.: a. Amphotericin B b. Nystatin </li></ul><ul><li>-MOA: blocks the microsomal P450 dependent demethylation </li></ul><ul><li>of lanosterol </li></ul><ul><li>-E.g. a. Clotrimazole & Miconazole </li></ul><ul><li>b. Ketoconazole </li></ul><ul><li>c. Fluconazole </li></ul><ul><li>- Terbinafine (Lamisil) </li></ul><ul><li>- MOA: inhibits squalene epoxidation </li></ul><ul><li>- higher cure rates for onychomycosis </li></ul>I. POLYENES II. IMIDAZOLE III. ALLYLAMINES
  15. 15. <ul><li>IV. POLYOXIN COMPOUNDS </li></ul><ul><li>- inhibit nucleic acid synthesis </li></ul><ul><li>-inhibitor of chitin synthetase </li></ul><ul><li>a. Flucytosine </li></ul><ul><li>- MOA: deaminate to 5-flurouracil,which inhibit DNA synthesis </li></ul><ul><li>- active only on yeast </li></ul><ul><li>- S/E: neutropenia & jaundice </li></ul><ul><li>b. Griseofulvin </li></ul><ul><li>- MOA: inhibit microtuble assembly </li></ul><ul><li>V. OTHER TOPICAL AGENTS </li></ul><ul><li>- whitfield’s ointment, tolnaftate,ciclopirox,halprogin & naftifine </li></ul><ul><li>• Flucytosine + Amphotericin B Synergistic </li></ul><ul><li>• Ketoconazole + Amphotericin B Antagonistic </li></ul>
  16. 16. SUPERFICIAL MYCOSES
  17. 17. <ul><li>- infection is limited to the dead cell layer of the skin & hair shaft </li></ul><ul><li>- skin  outermost layers of the stratum corneum </li></ul><ul><li>hair  involves the cuticle </li></ul><ul><li>- cellular immune response is not involved </li></ul><ul><li>I. SKIN </li></ul><ul><li>- fungal infection of the stratum corneum epidermidis </li></ul><ul><li>A. Pityriasis versicolor (lipophilic fungi) </li></ul><ul><li>- Pityrosporum ovale & orbiculare are part of the </li></ul><ul><li>normal flora </li></ul><ul><li>- are found in areas of the body rich in sebaceous </li></ul><ul><li>gland </li></ul><ul><li>- lesions are described as scales giving a dry chalky </li></ul><ul><li>appearance </li></ul><ul><li>- etiologic agent: Malassezia furfur </li></ul><ul><li>- clinical diagnosis: spaghetti & meatball appearance </li></ul>
  18. 18. <ul><li>B. Tinea nigra </li></ul><ul><li>- found on palmar & plantar areas of the stratum corneum </li></ul><ul><li>- lesions are described as light to blackish macular areas </li></ul><ul><li>- etiologic agent: Exiophiala werneckii </li></ul><ul><li>- clinical diagnosis: septate hypahe & budding yeast cells </li></ul><ul><li>- a dematiaceous fungi producing melanin </li></ul><ul><li>II. HAIR </li></ul><ul><li>A. Black Piedra </li></ul><ul><li>- hard black nodules found along the hair shaft </li></ul><ul><li>- affects scalp hair </li></ul><ul><li>- etiologic agent: Piedraia hortae </li></ul><ul><li>- clinical diagnosis: asci & ascospores </li></ul><ul><li>B. White Piedra </li></ul><ul><li>- development of cream colored soft pasty growths along the </li></ul><ul><li>infected hair shaft </li></ul><ul><li>- affects the hair of the axilla, beard, moustache,pubic & scalp </li></ul><ul><li>- etiologic agent: Trichosporon beigli </li></ul><ul><li>- clinical diagnosis: sleeve-like colarette around the hair shaft </li></ul>
  19. 19. CUTANEOUS MYCOSES
  20. 20. <ul><li>These are fungal diseases that affects the skin, hair & nails. </li></ul><ul><li>They are generally restricted to the keratinized layers of the </li></ul><ul><li>integuments & its appendages. They are also referred to as: </li></ul><ul><li>1. Keratinophilic fungi </li></ul><ul><li>2. Dermatophytes – tinea , ringworm </li></ul><ul><li>May give rise to hypersensitive state known as </li></ul><ul><li>dermatophytid or “id” reaction </li></ul><ul><li>There are 3 genera which are distributed accdg. to its geographical </li></ul><ul><li>distribution or by the area of the body involved </li></ul><ul><li>A. TRICHOPHYTON (Arthroderma) </li></ul><ul><li>- infects the skin, hair & nails </li></ul><ul><li>- microconidia>macroconidia </li></ul><ul><li>a. T.mentagrophytes – grape-like clusters on terminal </li></ul><ul><li>branch </li></ul><ul><li>b. T. rubrum – teardrop shaped microconidia </li></ul><ul><li>c. T. tonsurans – clavate microconidia </li></ul><ul><li>d. T. schoenleinii ( favic chandelier) </li></ul><ul><li>- leads to the formation of scutula (crusts) around </li></ul><ul><li>the follicle </li></ul>
  21. 21. <ul><li>B. MICROSPORUM (Nannizia) </li></ul><ul><li>-infects skin & hair </li></ul><ul><li>- macroconidia>microconidia </li></ul><ul><li>a. M. canis – macroconidia have curved </li></ul><ul><li>or hooked spiny tips </li></ul><ul><li>b. M. gypseum –thinner walled macroconidia </li></ul><ul><li>c. M. audouinii – thick walled chlamydospores </li></ul><ul><li>- fluoresce under Wood’s lamp </li></ul><ul><li>C. EPIDERMOPHYTON </li></ul><ul><li>- invades skin & nails </li></ul><ul><li>- Fuseaux in banana bunch </li></ul><ul><li>- E. floccosum </li></ul>
  22. 22. <ul><li>Clinical Features: </li></ul><ul><li>1. T. pedis – infected with Trichophyton or </li></ul><ul><li>Epidermophyton </li></ul><ul><li>2. T. corporis – infected with microsporum, </li></ul><ul><li>Trichophyton & Epidermophyton </li></ul><ul><li>- fungal infection of the globorous skin </li></ul><ul><li>3. T. cruris – infected with Trichophyton & </li></ul><ul><li>Epidermophyton </li></ul><ul><li>4. T. barbae – infected with Trichophyton </li></ul><ul><li>5. T. capitis </li></ul><ul><li>a. Endothrix infection – Trichophyton sp. </li></ul><ul><li>(T. tonsurans) </li></ul><ul><li>b. Ectothrix infection – microsporum sp. </li></ul>
  23. 23. <ul><li>Types: </li></ul><ul><li>a. Epidemic (Anthropophilic) </li></ul><ul><li>-caused bu M.audouinii </li></ul><ul><li>-occurs in children & contagious </li></ul><ul><li>b. Nonepidemic (zoophilic) </li></ul><ul><li>- caused by T.mentagrophytes or M.canis </li></ul><ul><li>- occurs primarily in children </li></ul><ul><li>- transmitted by pets </li></ul><ul><li>- may induce a severe combined inflammatory & </li></ul><ul><li>hypersensitivity reaction called kerion </li></ul><ul><li>c. Black dot </li></ul><ul><li>- caused by T. tonsurans </li></ul><ul><li>- occurs in adults & is a chronic infection characterized </li></ul><ul><li>by hair breakage </li></ul><ul><li>d. Favus </li></ul>
  24. 24. THE END
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