Mycology - 01 Intro to Mycology

• MYCOLOGY INTRODUCTION TO MYCOLOGY • • OUTLINE • • • Terminologies General Characteristics of Fungi o Prokaryote and Eukaryote o Characteristics of Fungi o Basic Forms o Reproduction o Medically Important Fungi Classification of Fungi o Fungi Classification o Clinical Purposes of Identification of Species • TERMINOLOGIES • • • • • • • • • • • • • • • • • • • • • • • Aerial – mycelium, hyphal units above the colony agar interface Anthropophilic – a fungus (dermatophyte) that preferentially grows on man rather than other animals or the soil. Arthroconidium – a thallic conidium released by either the splitting of a double septum or by the fragmentation or lysis of a dysjunctor cell. pl. arthroconidia Ascocarp – a fruiting body containing asci and ascospores Ascomycetes – a group of fungi that reproduce sexually by the endogenous formation of ascospores in an ascus. Ascospore – a haploid spore produced within an ascus following karyogamy and meiosis Ascus – a sac-like cell containing ascospores. Asci are characteristic of Ascomycetes. Pl. asci Aseptate – lacking septa often pertaining to the hyphae seen in zygomycetes Basidium – a cell that gives rise to a basidiospore. Basidia are characteristic of the Basidiomyc etes Basidiomycetes – a group of fungi that reproduce sexually by the exogenous formation of basidiospores from a basidium Basidiospore – a haploid spore produced on a basidium following karyogamy and meiosis Blastocatenate – a chain of conidia having the youngest cell at the tip Blastoconidium – an asexual conidium that forms by a blowing out or budding process. Pl. blastoconidia Base – junction of a bud and the mother cell of a yeast Bud – a type of asexual reproduction commonly found in yeasts Capsule – hyaline mucopolysaccharide covering around the body of certain yeasts (Cryptococcus, Rhodotorula) Catenulate – conidia arranged in chains Clavate – club-shaped Cleistothecium – an enclosed ascocarp containing randomly dispersed asci. Pl. cleistothecia Collarette – a remnant of a cell wall present at the tip of a phialide, or around a sporangiophore Columella – a sterile dome-like structure at the tip of a sporangiophore or within a sporangium. Chlamydospore – thick-walled resistant resting spore, esp in Histoplasma capsulatum Coenocytic – without septa • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Columella – a sterile invagination of a sporangium (Zygomycetes) Conidiogenous cell – cell that gives rise to a conidium Conidium – reproductive propagule produced in the absence of nuclear recombination, representing anamorphic or asexual reproduction Conidiophore– specialized hypha that gives rise to, or bears a conidium Dermatophyte – infection of hair, skin and nails caused by fungi other than dermatophytes Dematiaceous – fungus having brown or black melanotic pigment in the cell wall Dichotomous – type of branching of hyphae that is repetitious without pattern, branches are approximately equal in size and the stem from which they originated Dimorphic – having two forms Deuteromycetes – an artificial subdivision to accommodate those fungi where only the asexual state is known Dichotomous – a type of hyphal branching into two equal forks Dysgonic – a slow growing variant Echinulate – covered with delicate spines Ectothrix – forming a sheath of arthroconidia on the outside of a hair shaft. Cuticle of the hair is destroyed. Endothrix – arthroconidia formed inside a hair shaft. Cuticle of the hair remains intact Floccose – fluffy or cottony Fruiting body – reproductive structures of fungi (spores) Fungemia – presence of fungi in the blood Germ tube – initial hypha from a sprouting conidia, spore or yeast Heterothallic – a fungus that requires mating between two compatible strains for sexual reproduction to occur Hilum – a scar at the base of a conidium Holoblastic – a mode of blastic conidium ontogeny in which all the cell wall layers of the conidiogenous cell are involved in conidium development Holothallic – amode of thallic conidium ontogeny in which all the cell wall layers of the conidiogenous cell are involved in conidium development Homothallic – a fungus capable of sexual reproduction on a single thallus Hyaline/Hyalo – colourless Hypha – a single/vegetative filament of a fungus. Pl. Hyphae Intercalary – formed within a hyphal unit Macroconidium – the larger of two different types of conidia produced by a fungus in the same manner Microconidium – smaller of two types of conidia produced in the same manner by the same fungus Mycelium – mass of hyphae making up a fungus colony Metula – a sterile cell below the phialides of some Aspergillus and Penicillium species. Pl. Metulae Microconidium – the smaller of two different types of conidia produced by a fungus in the same manner Niger – black Nonseptate – without septa Pectinate – like the teeth of a comb Phaeo – darkly pigmented • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Pseudohypha – fragile string of cells that result from the budding of blastoconidia that have remained attached to each other Pellicle – a film-like or skin-like surgace growth Penicillus – the brush-like conidiophore of Penicillium. Pl. Penicilli Phialide – a specialized conidiogenous cell that produces conidia in basipetal succession without increasing in length Pleomorphic – having more than one form Pseudohyphae - a string of elongated blastoconidia formed in some yeasts that resemble a hypha-like filament Pyriform – pear-shaped Racquet hyphae – a hypha composed of a number of cells swollen at one end resembling a tennis racquet Rhizoid – root like structure. Used in the ID of some Zygomycetes Septum – a cross wall in a hypha. Pl. septa Spinulose/Spinose – covered in small spines Sporangiophore – specialized hypha that gives rise to a sporangium Sporangiospore – an asexual spore produced within a sporangium; reproductive unit formed in a sporangium Sporangium – a sac-like structure producing asexual spores endogenously by cytoplasmic cleavage. Spore – a reproductive propagule formed by either meiosis or mitosis. However, if by asexual means, cleavage of cytoplasm is usually involved. Stellate – star-shaped Sterigma – a small pointed structure upon which a basiospore forms. Pl. sterigmata Stolon – a running hypha from which rhizoids and sporangiospores arise Septum – a cross wall Teleomorph – sexual state of a fungus Terminal – formed at the end of a structure Tuberculate – spines or finger-like projections on macroconidia (Histoplasma capsulatum); wart like structures Thallic – a mode of conidial ontogeny where a conidium is formed from a pre-existing hyphal segment or cell Toruloid – having swellings at intervals Uniserate – phialides arising directly from a vesicle as in Aspergillus Verrucose – having many warts Vesicle – swollen or bladder-like cell Yeast – unicellular fungus, usually round or ovoid, that reproduces by budding Zoophilic – infecting lower animals rather than man Zygospores – a thick-walled sexual spore formed by the fusion of two similar gametangia; characteristic of the Zygomycetes GENERAL CHARACTERISTICS OF FUNGI • • Mycology- is the study of fungi. Mycotic Infections/Fungal Infections o Infection to the human body ▪ Fungus can cause allergic reactions-respiratory problems. ▪ Growth of a fungus on or in the body • Superficial mycoses- Tinea pedis- Athlete’s foot PROKARYOTE AND EUKARYOTES Nuclear Body Cell Division Cell Wall Cytoplasmic Membrane Cellular Organelles Site of Energy Production Site of Protein Synthesis Prokaryote Not bound by a membrane Binary Fission Eubacteria- with peptidoglycan Eukaryote Membrane Bound Cytoplasmic Membrane Free Ribosome Mitochondria Mitosis Animals/Protozoa – without Plants/Fungi/Algae – with cell wall (Cellulose or Chitin) Phospholipid bilayer Phospholipid bilayer without carbohydrate with carbohydrate and and sterol sterol Absent Present Rough ER CHARACTERISTICS OF FUNGI • • • • • • Eukaryotic Obligate or facultative aerobes achrolophyllous Environmental saprobe/saphrophytic spore-bearing, heterotrophic-absorb nutrients through the environment chemotrophic organisms that produce extracellular enzymes a FUNGAL MORPHOLOGY • • Cell membrane-sterols Cell wall o well defined o Chitin ▪ b1-4 n-acetyal glucosamine o b-glucans ▪ b1-3 glucose o cellulose in some ▪ b1-4 glucose BASIC FORMS Characteristics YEAST Cell structure unicellular spherical 3-5 micra Bacteria-like colony Reproduction MOLDS multicellular Filamentous 2-10 micra (mycelia – group of hyphae Aerial (extend above the surface) or vegetative spores Budding (blastoconidium – lysis-mitosis) Disease causing Opportunistic in Opportunistic in type immunocompromised debilitated & patients immunosuppressed patients Benefits Used in food Production of cheese; preparation antimicrobial (penicillin) Lab Test Biochem Microscopic MYCELIUM • • • Blastoconidia/blastospores- formed thru Budding – small outgrowth of hyphae pinches off • Formation of spores o Chlamydoconidia/chlamydospores According to pigmentation ▪ Hyaline ▪ Dematiaceous/Phaeoid Two Parts of Mycelium o Mass of branching intertwined hyphae/moulds ▪ Thallus/Vegetative • Favic chandelier • Nodular • Raquet hyphae • Spiral • anthler o Aerial/Fruiting bodies REPRODUCTION ASEXUAL REPRODUCTION • • • • • Conidiospores: produced at the tips of specialized hyphae o Conidia ▪ 2Types: Microconidia and Macroconidia Mycelium - mass of intertwined hyphae accumulating during active growth Types o According to presence/absence of cross-walls ▪ Septate ▪ Aseptate o • • Spores with mitotically derived nuclei Fragmentation . Budding Formation of spores Sporangiospores: produced in sporangia (sac-like structures) located on a sporangiophore. o Phialoconidia o Annelloconidia o Sporangiospore o Arthroconidia-fragmentation of hyphae • Basidiospores - sac-like -club shaped SEXUAL REPRODUCTION • • • • Spores meiotically derived nuclei Homothallic Heterothallic Ascospores - ascus (sac-like) MEDICALLY IMPORTANT FUNGI • • • Zygospores - identical cells • • Oospores - non-identical cells • • Medically important fungi are in four phyla: o Ascomycota o Basidiomycota o Mycorales o Deuteromycota Ascomycota - Sexual reproduction in a sack called an ascus with the production of ascopspores.( Aspergillus, Blastomyces dermatidis, Histoplasma capsulatum) o Ascomycota: (35000) ▪ septate mycelium ▪ simple septa ▪ monokaryotic, haploid mycelium ▪ production of complex sporocarps ▪ often dominant asexual reproduction Basidiomycota -Sexual reproduction in a sack called a basidium with the production of basidiospores. (Cryptococcus neoformans) o Basidiomycota: (22500) ▪ septate mycelium ▪ clamp connections ▪ complex dolipore septa ▪ dikaryotic, haploid mycelium ▪ production of complex sporocarps Mucorales (Zygomycota) - sexual reproduction by gametes and asexual reproduction with the formation of zygospores.( Rhizopus, Mucor) o Zygomycota: (1000) ▪ generally coenocytic mycelium ▪ no sporocarp production Deuteromycota (Fungi Imperfecti \Mitosporic Fungi) no recognizable form of sexual reproduction. Includes most pathogenic fungi ( Sporothrix, Coccidioides immitis, Candida, Pneumocystis). o o CLASSIFICATION OF FUNGI FUNGI CLASSIFICATION GEOPHILIC • • • • Usually recovered from soil but occasionally infect humans and animals Inflammatory lesion that may heal spontaneously Respond well to therapy Examples are Microsporum cookie, Microsporum fulvum, Microsporum nanum and Microsporum gypseum ZOOPHILIC • • • • Found primarily in animals and cause marked inflammatory reactions in humans who have contacted with cats, dogs, cattles or other animals. This is followed by rapid termination of the infection Inflammatory lesion that may heal spontaneously Respond well to therapy Examples are Microsporum canis, Microsporum equinum, Microsporum gallinae and Trichophyton mentagrophytes • • ANTHROPOPHILIC • • • Organisms that infect human Chronic infection and difficult to cure Examples are Microsporum audouinii, Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton tonsurans and Epidermophyton floccosum CLINICAL PURPOSES OF IDENTIFICATION OF SPECIES • • To determine possible source of infection Prognostic value SUPPLEMENTAL NOTES • • • • • • • • • Mycology - study of fungi, their relationship with each other, and other organism, and the unique biochemistry that set them apart from their groups of organisms There are serval fungi that can cause diseases (fungal diseases) Until the 1800s, it was assumed that fungi were simply a different kind of plant Mushrooms are eaten, used as medicines, used for the hallucinogenic agent Many Greek philosophers and naturalist considered fungi but assumed them as plants By mid-1800s, the microscope was invented an scientists began to examine the inner workings of fungi Microscopes reveal that fungi have distinct features separate from plant and animal cells The term mycology as coined in 1836 in a paper by MJ Berkeley when fungi were beginning to eb recognized as their own unique kingdom General Characteristics of Fungi o Eukaryotic and all are gram positive o Heterotrophs - they obtain nutritional requirements from organic material o Obligate or facultative aerobes ▪ Obligate - require oxygen for growth ▪ Facultative - may or may not require oxygen o Achlorophyllous - do not possess chlorophyll • Thallophytes - rootlike structure to obtain nutrition Classification of Fungi ▪ Saprobe/saprophytic - they live in dead/decaying environment ▪ Parasitic - obtain nutrition by living on another organism and absorb nutrients from their host ▪ Symbiotic - live having interdependent relations association with other species which both are mutually benefitted o Spore-bearing, heterotrophic -- absorb nutrients through the environment o Chemotrophic organisms that produce extracellular enzymes o Fungi are yeasts (moist) and/or molds (filamentous) o Dimorphic - Displays both yeast and mold form o They are thermally dimorphic when dependent on temperature o Polymorphic - have more than one form or stage Fungi are one of the most important organisms in the planet that plays a vital role in the biosphere and has a great economic importance on account of their both benefits and harmful effetcs Beneficial uses of fungi o Use as food (mushroom) o For food production (yeast for baking, cheese, etc) o Fermentation of alcoholic drinks (beer) o Tobacco and rubber manufacturing o For waste disposal (decomposition) o Used for products of antibiotics (penicillin) and immunosuppressive drugs (cyclosporin) o Used as biocontrol agents (involved in exploiting insects, small worms; help in controlling tests Harmful effects of fungi o Attacks all materials especially wood o Spoilage of stored food o Destroys crops o Spontaneous combustion of stacks of hay and peat Characteristics YEAST Cell structure unicellular spherical 3-5 micra Bacteria-like colony (round or oval shape) Reproduction MOLDS multicellular Filamentous 2-10 micra (mycelia – group of hyphae) Aerial (extend above the surface) or vegetative spores asexually by fission or Budding (blastoconidium – lysis-mitosis) Disease causing Opportunistic in Opportunistic in type immunocompromised debilitated & patients immunosuppressed patients Benefits Used in food Production of cheese; preparation antimicrobial (penicillin) Lab Test Biochem Microscopic • Fungal Structures o Cell Wall ▪ Rigid structure - 80-90% carbohydrates (chitin, mannan, glucan) ▪ Activate compliment leading to inflammation ▪ Surface components mediate attachment to host cells ▪ Release antigens that elicit antibodfy response ▪ Some contain melanin pigment (dematiaceous fungi) • Impart brown/black color • Diagnostic and associated with virulence o Capsule or Slime Layer ▪ Mainly polysaccharides ▪ Cause cells to adhere and clump together ▪ May influence the growth of fungi ▪ Usually outermost covering o Cell membrane ▪ Bilayered composed of phospholipids and sterols ▪ Function: • Protects the cytoplasm • Regulates intake and secretion of solutes • Facilitate synthesis of cell wall & capsular materials o o • • • Mycelium o Group of hyphae o May have its own nucleus, septum (if septated), vacuoles o Mass of intertwined hyphae accumulating during active growth o Types ▪ Presence or absence of cross walls • Aseptate/coenocytic - absence of cross walls • Septate - presence of cross walls ▪ Presence or absence of pigmentation • Hyaline - colorless • Dematiaceous - pigmentation • Pigment can be associated with virulence Hyaline dematiaceous Before aerial part shows up, embedded are vegetative part that starts to grow Rhizoids - rootlike structure, spreads within the bread and after several days the aerial hyphae will start to grow out o Reproductive structures are found in basidium Yeasts reproduce asexually by budding (Blastospore and Chlamydospore) Dimorphic fungi o Changing their morphology from mold to yeast phase or from yeast to mold depending on growth condition o Yeast - (parasitic or pathogenic) ▪ Form usually seen in tissue, exudates, of cultured in an incubator at 37C o Mycelium (saprophytic or mold form) ▪ Form observe in nature or when cultured at 25C • Kingdom Fungi o Phyla ▪ Chytridiomycota • Form motile spores called zoospores • Meiosis occurs in resting sporangium ▪ Glomeromycota • Forms spores containing hundred of nuclei; no known sexual reproduction ▪ Zygomycota • Form asexual spores called sporangiospores • Meiosis occurs in zygospore • They produce sexually when the environmental conditions become unfavorable • To reproduce sexually, two opposing mating strains must fuse or conjugate thereby sharing genetic content and creating zygospore • The resulting diploid zygospores remain dormant and protected by thick coat until environmental conditions have improved • When conditions become favorable, zygospores undergo meiosis to produce haploid spores which will eventually grow into a new organism • Ex. Common bread mold (Rhizopus stolonifera) - rapidly propagate on the surfaces of bread, fruits, and vegetable, most terrestrial in habitat • Some may become parasites of plants, insects, and some animals while other have symbiotic relationships with plants • Have thallus of cynocytic • Nucleus are haploid when the organism in the vegetative stage • Usually reproduce asexually by producing sporangiospores • The black tips of bread mold are swollen sporangia packed with black spores • When the spores land, on a suitable substrate, they usually germinate a new mycelium ▪ ▪ Ascomycota (including Deuteromycetes) • Form asexual spores called conidia • Meiosis occurs in ascus • Known to have a large member • Largest phylum of fungi • Defining feature is ascus (microscopic sexual structure where nonmotile spores called ascospores are formed) • Some species are asexual (do not have a sexual cycle and do not form asci/ascospore • Ex. Morrels, truffles, brewer’s yeast, baker’s yeast, dead man’s finger and cap fungi • The fungal symbionts in the majority in glycan like flantonia belong also to ascomycota • Spore-shooter • Produce microscopic spores inside a special elongated cells/sacs known as asci which give the group its name • Asexual reproduction is the dominant form of propagation and responsible for rapid spread of fungi into new areas • Biggest group of fungi having diverse habitat, cosmopolitan and derive many useful products, foods, medicine, chemicals • Entire brewing, bread, and cheese-making industry depend on these for fermented products • Antibiotic penicillin from Penicillium chrysogenum • Cyclosporin from Tolypocladium niveum used in organ transplant and autoimmune diseases • Many organic acids and enzymes are produced by ascomyces o Citric acic, gluconic acid, amylases, proteases • Claviseps purpurea or ergot used as medicine to stop excessive bleeding during menstrual period and speed up labor • Cheese are from different penicillium species • Aspergillus - used to prepare soy sauce and other Asian alcoholic beverages • Morrels, truffles, and lobster mushroom used as fungal delicacies • Neurospora, saccharomyces - used to study genetics Basidiomycota • Meiosis occurs in basidium • Mushrooms, puffballs • Filamentous • Reproduce sexually produce 4 spores, basidiospores • Large and diverse phylum of fungi • Includes jelly and shelf fungi, mushrooms, puffballs, stinkhorns • Certain yeasts • Typically filamentous composed of hyphae • Most reproduce sexually with a club shaped spore bearing organ called basidium that usually produces four sexual spores called basidiospores • • • • Born on fruiting bodies called basidiocarp (large and conspicious in all except for yeast) Reproduce asexually by budding or asexual spore formation o Budding - outgrowth of the parent cell is separated into a new cell o Any cell in the organism can bud o Asexual spore formation take place at the end of specialized structure called conidiospore o Septate of terminal cells become fully define dividing a random number of nuclei into individual cells o Cell wall thicken into protective coat the protected spores breaks off and are dispersed Sexual reproduction takes place in fruiting body in a specialized structure called basidia o Basidia - formed by plasmogamy between mycelia from two different spores o Plasmogamy - results in binutriate hyphae (with 2 types of nuclei; one from each parent) o In the gills of the fruiting body, some cells undergo fusion of these two nuclei, these now diploid cells are the basidia o The diploid phase is very brief, soon after fusion, meiosis takes place resulting in four haploid nuclei o The nuclei then migrate to the terminus of the basidium and form four individual projections o The projections are separated by cell walls to become spores • • • • • • • o ▪ Deuteromycota • Asexual reproduction by conidia • Fungi imperfectii, imperfect fungi • Based only on asexual stage • Only asexual reproduction occurs typically conidia born on conidiophores • Occurs as saprophytes on wide range of substrates • Large number are parasites on plants and animals • Causes a variety of disease like leaf spots, blights, blots, wilts, rots, etc. • Important diseases of plant Diseases like meningitis, candiasis, skin diseases, nail disease, are caused in Animals Mycelium of made up of profusely branched and septate hyphae posing multinucleate cells and simple pore septa the hyphae may be intracellular and their cell wall chiefly contain chitin glucan Reproduce only asexually, takes places by hyphal fragments, budding, arthrospores, chlamidospores, and others Cell of conidiophores producing conidia is called conidiogenous cell which is produced in the tip or at the side of the conidiogenous cell (single or in chain) Either free or aggregated to form a specialized structure like synnemata and sporodochia When they are large, the condiophores are formed in specialized fruiting layers which are present within the specialized fruiting bodies called conidiomata There is low sexual reproduction Parasexual cycle generally operates in their life to fulfill sexual requirements 4 important groups ▪ Zygomycetes • Formed by the fission of two different sets • sexual spores are known as zygospores; • asexual spores - sporangiospores • Hyphae are aseptate ▪ Ascomycetes • Aka sock fungi • Can be coprophilous, decomposers, parasitic, or saprophytic • Sexual spores - ascospores • Asexual spores by conidiospores ▪ Basidiomycetes • Mushrooms that are commonly found • Mostly live as parasites • Sexual reproduction - basidiospores • Asexual reproduction - conidia by budding or fragmentation ▪ Deuteromycetes • Less important group • Aka imperfect fungi as they do not follow regular reproduction cycle as other fungi • Do not produce sexually • Asexual reproduction by conidia • Life Cycle of Fungi o Filamentous fungi can reproduce asexually by fragmentation of their hyphae o Fungal spores are formed from aerial hyphae and are used for both sexual and asexual reproduction o Asexual spores ▪ Formed by the aerial hyphae of one organism, new organisms are identical to parent ▪ Conidiospore - unicellular or multicellular spore formed within a hyphal segment ▪ Sporangiospore - asexual spore formed within a sac (sporangium) o Sexual spores ▪ Formed by the fusion of nuclei from two opposite mating strains of the same species ▪ New organisms are different from both parents ▪ Ascospores, Basidiospores, oospores o • • • • o o o o o o o o o o o o o In the beginning, all spores are haploid (have only single copy on entire genetic material) may migrate through the air by grabbing onto other organism After locating a favorable living environment, they will start to germinate and they will grow a bunch of root like structure (mycelium) The nutrients are transferred through the mycelium into the other spores to develop When mycelium grows and develop, it may encounter another fungi If the two fungi are compatible, a cell of each mycelium will fuse together to form into a new single cell The new fused cells are diploid as they have more than one copy of genetic information which will undergo meiosis After fungi becomes mycelium, it enters meiosis During meiosis, single cells splits into two cells and genetic materials from both parents gets mixed up The produced daughter cells have no identical features from their parent and do not look similar For asexual reproduction, during mycelium stage, the fungi has the choice of reproducing sexually or asexual Asexual lifecycle produces mitospores which are identical to the parents Mitospores later grow into a new set of mycelium and the entire life cycle repeats again Life cycle of a fungi is complex in nature as they do not reproduce in one way, their reproduction depend on the environmental conditions • Due to their distinct nature, a fungus is capable of surviving anywhere and everywhere o The vegetative thallus predominates in the life cycle of a fungus o Thallus may be haploid (1n), dikaryotic (n+n), or diploid (2n) in different groups of fungi o Ploidy of thallus is determined by the timing of these events in the life cycle ▪ Plasmogamy (cell fusion) ▪ Karyogamy (nuclear fusion) ▪ Meiosis (reduction division) Working Schema in identifying fungi o Identify form ▪ Yeast - oval, circular, budding ▪ Mold - presence of hyphae or mycelium • Observe hyphae Reproductive Forms o Teleomorph - sexual form; two fungal nuclei unite and undergo meiosis forming offspring with new genetic information ▪ Fungi with teleomorphic state are perfect fungi ▪ This is a result of plasmogamy and nuclear recombination o Anamorph - asexual form ▪ Somatic, reproductive structure that originates without nuclear recombination ▪ Imperfect part of life cycle of fungi o Synanomorph - different asexual forms in the sam fungus ▪ Different asexual forms in the same fungus ▪ same fungus growing in a different form Mycoses o Infection caused by fungus o Superficial cutaneous mycoses ▪ Infections involve the hair, skin, or nails without direct invasion of deep tissue ▪ Only invade stratum corneum in the superficial layer of the skin ▪ Do not invade living tissue nor provoke an immune response by the host o Subcutaneous mycoses ▪ Confined to subcutaneous without dissemination ▪ Penetrates the epidermis and dermis to infect the deeper tissue o Systemic mycoses ▪ Involve lungs but can disseminate to any organ ▪ Spreads throughout the body o • • • Opportunistic mycoses ▪ Affect patients are immunocompromised ▪ May be systemic ▪ Do not normal cause disease in healthy people but cause disease in people with weakened immune defenses ▪ Weakened immune function may occur due to inherited immunodeficiency disease, drugs suppressing immune systems, radiation therapy, infections like HIV, cancer, diabetes, old age, malnutrition Diseases o Types of pathogens ▪ Primary ▪ Opportunistic o Common Virulence Factors ▪ Size/number of organism ▪ Ability to grow at 37C and neutral pH ▪ Conversion from mycelial form to yeast or spherule form ▪ Toxin production Clinical Specimens o Respiratory secretions ▪ Antibiotic & antifungal should be in culture media ▪ Sputum - commonly used ▪ Report any fungal detected o CSF ▪ Should be filtered before culturing ▪ C. neoformans - common finding ▪ Perform the test right away by performing India ink test and inoculating into culture media o Blood o Hair, skin, nail scrapings ▪ Mycosel agar should be used ▪ Be careful that there is no contact with the medtech; use PPE when performing the test ▪ Perform scraping slowly so that they would fll directly into the slide or petri dish o Vaginal ▪ Common for women with Candidiasis ▪ Selective and inhibitory plates should be used o Urine - Presence of similar findings as vaginal swabs o Tissue, bone marrow, sterile body fluids ▪ All tissues should be missed before culturing Culture o Recommended media ▪ w/ or w/o cycloheximide or antibacterial agent ▪ cycloheximide is mixed with media to prevent growth of rapidly-growing contaminating molds ▪ media can be used w/ or w/o antibacterial agents (gentamycin, chloramphenicol, ciprofloxacin) to kill the contaminating bacterial species ▪ antibacterial media are not required if the sample is taken from an uncontaminated sites o Agar plates are preferred over screw capped agar ▪ Better aeration ▪ Larger surface area ▪ Greater ease of handling o Incubation ▪ Room temp (30C) ▪ Minimum of 21-30 days ▪ Humidity range of 40-50% ▪ Examined at least 3x a week • Fungus may grow slowly • Direct Detection Methods o Potassium hydroxide (KOH) preparation o Calcofluor white stain ▪ Superior to KOH o India ink stain ▪ Negative type of stain ▪ Background is colored, fungus is colorless ▪ Performed in CSF (C. neoformans) ▪ Positive - yeast is colorless o Lactophenol cotton blue mounts o Grocott’s methenamine silver (GMS) stain o Periodic acid-Schiff (PAS) stain o Can be used directly into sample ▪ Wait 10-30 before observing under microscope o Structures to observe during observation ▪ Find any structure (spore, hyphae growing) • Report as positive for fungal element • No need to identify specific fungus (usually) • Colonial Morphologic Characteristics of Molds o Color - noted on front and reverse surfaces o Topography ▪ Verrucose - furrowed/convoluted ▪ Umbonate - slightly raised in the center ▪ Rugose - furrows radiate out from the center o Texture ▪ Cottony - loose, high aerial mycelium ▪ Granular - dense and powdery ▪ Wooly - high aerial mycelium slightly matted down o Incubation temp is also important • Cottony (upper); wooly (lower) • Powdery (lower) • • Microscopic preparation o Adhesive-tape preparation o Wet mount - using KOH, lactophenol blue o Tease mount - inoculating from media o Microslide Morphologic Characteristics of Molds o Dermatophytes tend to produce the following ▪ Freely branching “antlerlike appearance ▪ Racquet appearance ▪ Spiral hyphae Zygomycetes o Rhizopus ▪ Genus of saprophytic and parasitic fungi ▪ Found in moist or damp places ▪ Found on organic substances like vegetables, fruit, bread, jellies ▪ Vegetative structure is made up of semicoenocytic and branched hyphae ▪ Used to produce chemicals and alcoholic products ▪ Some species may cause plant disease and may cause infectiosn in humans o Mucor ▪ Filamentous fungus found in soil, plants, decaying fruits, and vegetable ▪ Ubiquitous in nature, common laboratory contaminant ▪ May cause infection in man, frog, amphibians, cattle, and swine ▪ Most species are unable to grow at 37C ▪ Strains isolated in human infection are one of the thermotolerant specis o Lichtheimia ▪ Thermophilic fungus ▪ Normally lives as a saprophytic mold that can be an opportunistic pathogen known to cause pulmonary, CNS, rhinocerebral, cutaneous infection in animals and human with impaired immunity o Syncephalastrum ▪ Filamentous fungus commonly isolated in soil and animal feces particularly in tropical and subtropical areas ▪ Heterothallic and requires mating strain to produce zygospores ▪ Commonly considered as contaminant ▪ Rarely associated with human disease o Cunninghamella ▪ Filamentous fungus found in soil and plant materials particularly in Mediterranean and subtropical zones ▪ Recovered from animal material, cheese, Brazil nuts ▪ Common contaminant ▪ Opportunistic fungus that may cause infections in immunocompromised host o General Characteristics ▪ Large, ribbonlike hyphae ▪ Occasional septa ▪ Sporangia - saclike fruiting structures ▪ Sporangiospores - internally spherical spores ▪ Sporangiophore - supporting structure for sporangium o Epidemiologic factors ▪ Has worldwide distribution ▪ Found on decaying organ matter, bread, or in the soil ▪ Infection is acquired though inhalation, percutaneous routes, or the ingestion of spores o Zygomycosis ▪ Infection of zygomycetes ▪ Patients who are immunocompromised are at risk • Uncontrolled diabetes • Those with prolonged drug therapy ▪ o Disease • Vascular invasion, particularly rhinocerebral • Tissue thrombosis and/or necrosis • Perineural invasion • Lung infections • Gastrointestinal (GI) infections Morphologic Characteristics ▪ Appear fluffy ▪ White-gray to brown ▪ Hyphae are grayish and dotted with dark sporangia o Trichophyton ▪ Includes parasitic varieties cause Tinea including athlete’s foot, ringworm, jock itch, and similar infection of the nail, beard, skin, and scalp ▪ Characterized by development of both smooth walled macro and microconidia ▪ Identification • Macroconidia - mostly born laterally directly on the hyphae or short pedi cells that may be thin or thick walled o Smooth, club-shaped, and thin-walled o Clavate to fusiform and grains from 4-8 x 8-50 mcm in size o Few or absent in many species • Microconidia are spherical, pyriform (teardrop), or clavate (clublike) or of irregular shape; Range 2-3 x 2-4 mcm in size ▪ General characteristic • Widely distributed • Infected hairs do not fluoresce under Wood’s lamp (UV) ▪ Invasion • Endothrix - hair shaft is filled with arthroconidia • Ectothrix - spores are found around hair shaft ▪ T. rubrum • Does not perforate hair • Slow growing • Has a cherry-red reverse surface • Colonies are fluffy or granular • Macroconidia o Thin-walled o Smooth-walled o Multicelled o Cigar-shaped (3-8 septa) ▪ T. mentagrophytes • Perforates hair • Rapid growing • Has an orange-red reverse surface • Colonies are downy or granular • Macroconidia o Thin-walled o Smooth-walled o Cigar-shaped (2-5 septa) o Narrow attachment to base) o Microsporum ▪ Causes Tinea capitis, corporis, ringworm, and other dermatophytosis ▪ Forms both macroconidia and microconidia • Macroconidia - hyaline multi-septate and variable in form (fusiform, spindle shape); 720 x 30-160 mcm in size; thin or thick echinulate to verrucose cell walls • Microconidia - hyaline single celled pyriform to clavate smooth walled; not diagnostic ▪ • Important Fungal Structures • Mycelium - cluster of hyphae • Hyphae - threadlike thin structures that form mycelium network • Columella - where sporangiophore swells up to form a domelike structure can varie in both shapes and sizes • Sporangium - round and thick outer covering which carries numerous spores; can be globous or spherical • Spores - reproductive structures formed within the sporangium which care simple, flattened, and variable in shape and size ▪ Mucor - mycelium is highly branched forming a fine network of hyphae; hyphae is filamentous, aseptate, coenocytic; sporangiophore is elongated slightly narrow; color of colony is white to gray and turns to brown when culture becomes soddy; found in bread ▪ Lichteimia - wooly, white and gray brown to olive green as it age; usually has a apical projection columella or dome-shaped; single-celled hyaline subglobous or more rarely broadly ellipsoidal; sporangiophore is apically with the welldeveloped funnel-shaped or swollen apophysis Dermatophytes o Produce infections involving hair, skin, and nails, mucous membranes, feathers, and other body surfaces causing ringworm and related diseases o Etiologic agents ▪ Trichophyton (hair, skin, and nails) ▪ Microsporum (hair and skin) ▪ Epidermophyton (skin and nails) o Disease - cause cutaneous mycoses ▪ Tinea corporis - ringworm of the body ▪ T. cruris - ringworm of the groin ▪ T. capitis - ringworm of the scalp ▪ T. barbae - ringworm of the beard ▪ T. unguium - ringworm of the nails ▪ T. pedis - ringworm of the feet ▪ • Large, spindle-shaped, rough-walled macroconidia ▪ Thick walls with four or more septa ▪ Small and club-shaped microconidia ▪ Cultures that produce aerial hyphae • Texture - velvety, powdery, glabrous, or cottony • Color - whitish, buff to cinnamon brown ▪ M. audouinii • Causes Tinea capitis among schoolchildren • Spread by infected hair • Infect hair shafts fluoresce yellow-green ▪ M. canis • Causes ringworm in children and adults • Spread by infected animals • Infect hair shafts fluoresce yellow-green Opportunistic Mycoses o Cause tissue invasion in individuals who are immunocompromised o Organisms are saprophytic and therefore difficult to diagnose o All fungi should be identified in the patients o Are acquired through ▪ Construction ▪ Demolition ▪ Remodeling ▪ Hospital visits o Aspergillus ▪ Capable of disseminated infection and a wide variety of other infections • Sinus fungus ball • Otomycosis • Onychomycosis ▪ Identification • A. fumigatus o White to blue-green colony o Dichotomous branching of hyphae o Short or long conidiophores with a foot cell at base • A. niger o Yellow colonies that turn black o Darkly pigmented spores (macroscopic) o o o o o o o o • Penicillium ▪ Usually green to blue-green colonies ▪ Velvety surface ▪ Hyaline septate hyphae ▪ Brushlike conidiophores Systemic Mycoses o Are produced by dimorphic fungi ▪ Blastomyces dermatitidis ▪ Coccidioides immitis ▪ Histoplasma capsulatum ▪ Paracoccidioides brasiliensis ▪ Penicillium marneffei ▪ Sporothrix schenckii Serologic testing or biopsy detects most infections Patients who are immunocompromised tend to exhibit disseminated infection Most commonly found in North America Blastomyces dermatitidis ▪ Found in Ohio & Mississippi River Valley regions ▪ Blastomycosis occurs in dogs and humans ▪ Produces acute or chronic suppurative and granulomatous infections ▪ Identification • Large, spherical, thick-walled yeast (8-15 mcm) • Single bud connected to the parent cell Coccidioides immitis ▪ Found in the desert southwest of the United States ▪ Acquired by inhalation of arthroconidia ▪ Causes respiratory tract infections ▪ Considered a select agent ▪ Identification • Nonbudding, thick-walled spherule (20-200 um) • Spherules containing nonbudding endospores Histoplasma capsulatum ▪ Seen in Midwestern and southern United States ▪ Associated with the inhalation of aerosolized conidia: • Chicken houses • Roosting places for birds (starlings) • Bat guano (in caves) ▪ Produces chronic granulomatous infection ▪ Identification • May be detected in bone marrow or using Wright stain • Intracellularly found in cells as small roundto-oval yeast cells (2-5 um) • Demonstrates tuberculate macroconidia (mycelial form) Sporothrix schenckii ▪ The rose gardener’s disease ▪ Acquired through trauma (thorns) ▪ Appears as to round-to-oval yeast cells ▪ Demonstrates ovoid microconidia in mycelial form ▪