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