2Learning Outcome Able to define terms use in mycology Can describe basic characteristic of fungiAble to discuss fungal reproductionAble to describe mycosesAble to discuss laboratory examination for fungal infection.
4Definitions Mycologists--scientists who study fungi Mycology--scientific discipline dealing with fungiMycoses--diseases caused in animals by fungiMykos = mycete = fungus
5I. FUNGIDiverse group of heterotrophs.Many are ecologically important saprophytes (consume dead and decaying matter)Others are parasites.Most are multicellular, but yeasts are unicellular.Most are aerobes or facultative anaerobes.Cell walls are made up of chitin (polysaccharide).Over 100,000 fungal species identified. Only about 100 are human or animal pathogens.Most human fungal infections are nosocomial and/or occur in immunocompromised individuals (opportunistic infections).Fungal diseases in plants cause over 1 billion dollars/year in losses.
6Characteristic of fungi Vegetative HyphaComposed of cells involved in catabolism and growth.Reproductive Hypha (aerial)Composed of cells involved in reproduction (produce spores).
7General knowledge of the fungi Both sexual and asexual spore may be producedStore their food as glycogen (plant; starch)Fungi are heterotrophic organisms, lack of chlorophyll (plant; autotrophic)
8General knowledge of the fungi Yeast : unicellular, 370CBudding Yeast – may produce a pseudohypaFission yeastMold : multicellular, hyphae, 250CDimorphic fungi (thermally dimorphic fungi) : mold phase & yeast phase
9Yeasts Facultative Anaerobes Fermentation : ethanol and CO2 Non-filamentous unicellular fungiSpherical or ovalReproduction:a) by fission, orb). By budding
10Yeast Reproduction FISSION “even” reproduction, nucleus divides forming two identical cells, like bacteriaBUDDING“uneven” reproduction, parent cell’s nucleus divides and migrates to form a bud and then breaks away
13General knowledge of the fungi Eukaryotic microorganismsRigid cell walls: chitin, glucans, mannansPlasma membranes: ergosterolLysine synthesis by L- amino adipic acid (AAA) pathway and other organisms synthesize lysine by diaminopimelic acid (DAP) pathway
14Fungal Structure Thallus-”body” Mycelium – Molds & fleshy fungi have these structuresLong filaments of cells (hyphae):Septate hyphae (cross wall) :most fungiAseptate hyphae (coenocytic ) :no cross wall, continous mass with many nuclei .Mycelium –Abundance growth of aerial hyphae resulting a mass can be observed with unaided ayes
17Fungal Classification Four groups of true fungiZygomycetes (common bread mold—Rhizopus)Basidiomycetes (puffballs & common mushrooms)Ascomycetes (Dutch elm disease/rye smut)Deuteromycetes (fungi imperfection)
18Classification ( con’t) : First three groups is based on their method of sexual reproduction4th group, the Deuteromycetes, have NO sexual reproduction
19Fungi-Taxonomic classification SEXUAL SPORE CLASSZygospore ZygomycetesBasidiospore BasidiomycetesAscospore AscomycetesNone/Unknown---- Deuteromycetes(“Fungi Imperfecti”)
20Zygomycetes Asexual phase—Sporangium—bread mold (Rhizopus stolonifer) Sexual phase--- sporgangium ---shotgun fungus (lives on dung) it shoots its sporgangium explosively towards light or fly pathogen (Entomophthora muscae—--these types of fungi have been used as agents for biological control of insects
21Basidiomycetes Basidiospore Examples: boletes, puffballs,smuts, stinkhorns and tooth fungi
22Ascomycetes Asexual phase- Sexual phase (morels, lichens ) Conidiospores (Penicillium and Aspergillus)budding yeastSexual phase (morels, lichens )
23Life Cycle Fungal reproduce by 2 way Asexual Sexual Hyphae fragmentationAsexual sporesConidiosphoreArthroconidiaBlastoconidiasporangiospore
24Reproduction of Fungi 1. Sexual reproduction --Sexual spores 2. Asexual reproduction--Asexual spores3. Parasexual reproduction--Genetic exchange
25Life cycleConidiosphoreSpore that is not enclosed in sac
26Life cycle Athroconidia Form fragmentation of hypae into single thick cells.
27Life cycle Blastoconidia Buds coming from parents cells Chlamydoconium a variant which spore form by thickening and enlargement within hypae
28Life cycle Sporangiospore Spore form inside sporangium (sac) at the end of sporangiophore
34Conidial Fungus reproduces by means of asexual spores called conidia Conidia vary greatly in shape, size and colorMost of the common household molds & mildews are conidial fungi
35Asexual spores ( cont) Another type of Conidiophore: Blastospores A bud coming off the parent cellCandida albicans
36ChlamydosporeFormed within hyphaThick-walled sporeCandida albicans
37ChlamydosporesThe chlamydospore is a method of producing a substantial resting spore very quicklyNutrient is shunted from adjacent cells into a preferred cell and it swells up, converts nutrient materials to oil droplets for efficient storage, then rounds off with a thick, often roughened outer wall for protection
38Asexual spores Sporangiospores Hundreds formed within a sac (sporangium) at the end of an aerial hyphaRhizopus spp.Mucor sppAbsidia spp
43Sexual spores Have three stages Plasmogamy- a haploid nucleus of donor cellsKaryogamy- the (+) and (-) nuclei fuse to form a diploid zygoteMeiosis – the diploid nucleus give rise to haploid nuclei (sexual spores) genetic recombinant
48ZygomycosisDisease caused by fungi that are classifiable as ZygomycetesMucormycosis : Order MucoralesEntomophthoromycosis : Order Entomophthorales
49Zygomycosis (cn’t)Presents as a spectrum of diseases, depending on the portal of entry and the predisposing risk factors of the patient:Rhinocerebral zygomycosisPulmonary zygomycosisGastrointestinal zygomycosisCutaneous zygomycosisDisseminated zygomycosis
50Material from the periorbital tissue of a woman with poorly controlled diabetes mellitus with facial and periorbital swelling due to zygomycosis (see right picture) is stained with periodic acid-Schiff stain (X 560). The material demonstrates the classic appearance of irregularly shaped broad hyphae with right-angle branching (arrow).
51Laboratory to diagnosis of fungal infection Specimen collection and transportSpecimen processingDirect examinationSelection and inoculation of culture mediaIdentification
52LABORATORY DIAGNOSIS OF MYCOSES Direct microscopic examinationCultureSerology
53Specimen collection and transport must be material from the actual infection sitemust be carefully the contaminationmust be established for the best chance of recovery of causative microorganisms (optimal times)
54Specimen collection and transport ( con’t) must be obtained to perform the culture or other techniques request (sufficient quantity)must be used to ensure optimal recovery of microorganismsobtain cultures before the treatmentthe culture container must be properly labeled
55Specimen processing specimen should be examined as soon as possible direct examination :KOH mountCalcofluor whiteIndia inkculture media
56Selection and inoculation of culture media Culture media for recovery of fungi from clinical specimens. PDA, Corn Starch AgarThe recovery rate may be somewhat enhanced by using a variety of isolation media, considerations of cost, storage, incubator space and technologist time.
57Initial observations in the study of fungus isolates 1.Appearance of the growth2. Rate of growth3. Colony pigmentation4. Growth on media containing antifungal agents5.Dimorphic fungi
58Initial observations in the study of fungus isolates 1.Appearance of the growth- surface and reverse surface of colony were observed- delicate or hairlike hyphae2. Rate of growth- saprophytes : 3-5 days- dimorphic fungi : 10 days or more- dermatophytes : 14 days or more
59Initial observations in the study of fungus isolates 3. Colony pigmentation4. Growth on media containing antifungal agents- most strains of the dimorphic fungi can grow- most strains of the rapidly growing saprobes areinhibited5. Dimorphic growth- mold form (the environmental and infective form) ;ambient or room temperature (22-25 OC)- yeast form (invasive form) ;near body temperature (30-35 OC)
60Preparation of mounts for study The tease mountScotch tape preparationThe microslide culture technique( slide culture )
61Terms useful in the examination of fungi hypha and pseudohyphaemyceliumseptate or aseptate (or coenocytic) hyphaevegetative myceliumaerial myceliumreproductive mycelium