Mycology Lecture 1Medical Mycologyas lectured by Dr. MagatHRL, MaLt 2010

Fungi‣Aerobic, nucleated, achlorophyllous organisms which reproduce sexually and/or asexually‣Filamentous branched somatic structures surrounded by a true cell wall‣ Grow as a mass of branching, interlacing filaments

Reproduction‣Asexual reproduction

‣process of mitosis most common process by which spores are produced in fungi

‣Sexual reproduction‣alternating karyogamy and meiosis

‣Karyogamy – Nuclear fission‣Meiosis – Reduction division with a diploid nucleaus giving rise to four haploid products

‣Sexual (meiosis) by means of specialized cells called spores which on a suitable substrate, germinate, producing one or more filamentous process called GERM TUBES. Each germ tube elongates by growth of the distal end to become long filaments. Each filament is called HYPHA which eventually branch, rebranch and intertwine to form a mass called MYCELIUM

Parts of a Mycelium‣Aerial Mycelium

‣the mycelial portion above the surface of the medium. That portion of the aerial mycelium which develops reproductive spores is called the REPRODUCTIVE MYCELIUM

‣Vegetative Mycelium‣the mycelial portion that grows into the substrate and absorbs food for further growth.

Types of Hypha‣Nonseptate or Coenocytic

‣No transverse walls or septa divide the hyphae. Protoplasm and nuclear material are allowed to flow uninterruptedly throughout the filament

‣Septate‣Transverse walls or septa are formed at regular intervals along the filament. Majority of fungi have septate hyphae.

*the following are text from labels in the pictures in the powerpoint

A) Coenocytic hyphae or nonseptate hyphaeB) Septate hyphaeC) Septum

Hyaline hyphae lacking septations (aseptate)Antler hyphae showing swollen hyphal tips resembling

antlers, with lateral and terminal branching (favic chandeliers) Trichophyton schoenleinii

Racquet hyphae showing swollen areas resembling a tennis racquet

Spiral hyphae exhibiting corkscrewlike turns

Kinds of Colonies Produced by FungiYeast colonies - soft, pasty type of colony like yeast

produced by fungi which has mycelial formation which remains at yeast form at both 4˚C and 37˚C

Filamentous or Mold Colony - a mold type of colony with an aerial mycelium that appears cottony, wooly, powdery or granular. True mycelia are produced by spores which germinate to form branching hyphae.

According to Colony type at Different Termperatures, Fungi are:

A) Monomorphic or Monophasic ‣produce one type of colony at both room and

incubation temperatureo Cryptococcus neoformans – Yeast only

‣ Room Temperature colonies 37˚C Cultures

‣ Both room temperature and 37˚C culture are: off white, mucous colonies on Sabouraud medium after 5 to 10 days

o Aspergillus species – Filamentous only‣ Both room temperature and 37˚C culture

are: Green colonies after 5 to 10 days on Sabouraud medium. Colorless underside

o Candida albicans - Yeastlike colony‣ Both room temperature and 37˚C culture

are: White colonies incubated on Sabouraud medium for 5 to 7 days

B) Dimorphic or Diphasic ‣produce a yeast-like colony at 37˚C on incubation

temperature (yeast phase) and a filamentous type of colony at room temperature (mycelial phase)

o Sporothrix schenckii‣ Room temperature: Dark, greasy looking

cluture after 1 to 2 weeks incubation on Sabouraud medium

‣ 37˚C Cultures: White to tan Yeast colonies after 1 to 3 weeks incubation on brain or heart infusion agar

o Histoplasma capsulatumo Blastomyces dermatitidis‣ Room temperature: Cottony after 1 to 3

weeks incubation on Sabouraud medium. White colony brown to tan underside.

‣ 37˚C Cultures: Rough, dry, heaped-up yeast colony after 1 to 3 weeks incubation on brain heart infusion agar.

Classes of Spores distinguished in fungiA) Sexual Spores – produced by the fusion of two nuclei

which may or may not belong to the same strain within a specie

B) Zygospores – produced by the tips of approximating hyphae conjugating and resulting in large thick walled bodies from fusion of contents of the terminal portion

C) Basidiospores – sexual spores, typically 4 in number, produced at the ends of club-shaped structures called BASIDIUM

D) Ascospore – produced within an enlarged cell by nuclear fusion enclosed in a sac called an ASCUS or ASCOCARP. Typically, there may be 4-8 spores within an ascus

E) Asexual spores – arise by the differentiation of spore bearing hyphae without nuclear fission

F) Sporangiospores produced on a specialized hypha inside a round container known as SPORANGIUM. When it ruptures, the sporangiospores scatter and leave the thin walled sporangium in place or it may dissolve.

‣Large, sac l ike sporangia that contains sporangiospores, characterist ic of the Zygomycetes.

G) Conidiospores – produced on a specialized hypha and are freed from the hyphae by abstriction at the point of attachment. These spores or conidia vary greatly in size, shape, number of septations and these definite pattern aid in specie identification.

‣Conidia (asexual spores [A]) produced on specialized structures (conidiophores [B]) of Aspergillus

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Conidia According to SizeA) Microconidia – small and single celledB) Macroconidia – Large, multicellular, divided by either

or both transverse and longitudinal walls.*PIC‣Numerous small, spherical microconidia (A) contrasted with a

large, elongated macroconidium.‣Trichophyton tonsurans, showing munerous microconidia (A)

borne singly or in clusters. A single macroconidia (B) rarely present

Conidia According to ShapeA) Fusiform – spindle shapedB) Clavate – club shapedC) Muriform – multiseptate, both transverse and

longitudinal

PIC‣Microsporum canis showing several spindle shaped thick

walled multicelled macroconidia‣Epidermophyton floccosum, showing numerous smooth,

multiseptate, thin walled macroconidia that appear club shaped.

‣Alternaria spp. Showing muriform dematiaceous conidia with horizontal and longitudinal septa.

Conidia According to ArrangementA) Sessile and Lateral – develops directly on the side of

the hypha with no conidiophore or stem.B) En Grappe – clusteredC) Pedunculate – develop from the end of a short

conidiophore

PIC‣Trichophyton rubrum, showing numerous pyriform

micrconidia borne singly on hyphae‣Trichophyton mentagrophytes, showing numerous

microconidia in grapelike cluster (A). Also shown are several thin walled macrocondia (B).

ThallosporesA) Arthrospores – fragmentation or segmentation of

preformed mycelium results in the production of rectangular thick walled spores which are uniformly sized. Ex Geotrichum, Coccidioides immitis

‣Arthoconidia formation (A) produced by the breaking down of hyphal strand (B) into individual rectangular units

B) Blastospores – formed by a simple budding process from cells of the mycelium. Budding may be in one cell to one spore basis (Blastomyces dermatitidis) or multispore basis (Paracoccidioides braziliensis)

‣Blastomyces dermatitidis, yeast form, showing thick walled, oval to round, single budding, yeast like cells.

‣Paracoccidioides braziliensis in bone marrow showing yeast cell having multiple buds.

C) Chlamydospores – large, round, thick walled resting cells in a septate hypha or at the terminal ends. It is formed when the cytoplasm of these hypha become concentrated and these portions enlarge in a diameter greater than theat of the rest of the hypha. They may be intercalary, terminal or lateral. Ex. Candida albicans

‣Chlamydospores composed of thick walled spherical cells

*the following are labels of pictures in the powerpointDifferent Morphological Form of Fungi‣Scopularioposis

‣A- septate hyphae darker, slender long tubes; B- long chains of spores (approximately 5 microns in diameter, have a rough surface and are spherical)‣resembles Penicillium spp. Except spores are larger and form unbranched chains.

‣‣

‣Nigrospora‣Black spore; A- 9 jet black structures are the single celled spores (15 microns in diameter) B- Septate hyphae, long, slender, almost clear tubes

‣Gliocladium‣arising from the clear hyphae (A) are the spore bearing structures. The large dark masses contain from 30-50 small spores (B). The spores occur in clumps.‣Numerous small spores held together in a clump. Similar to Penicillium except for the clumping of spores

‣Alternaria‣Hand Grenade structures are the spores of this fungus (A). Each spore is approximately 20-4- microns and brown (dematiaceous) in color. Note that each spore has horizontal and longitudinal septa. Also note the septate, dematiaceous hyphae (B).‣Large hand grenade shaped spores with both longitudinal and transverse cross walls. Borne singly or in chains. Septate, dematiaceous hyphae.

‣Rhizopus‣it is characterized by coenocytic hyphae (A) the formation of rootlike structures called Rhizoids (B) and the dark spherical structure known as sporangium (up to 100 sporangiospores).‣similar to Mucor spp. Except rootlike structures (rhizoids) at base of sporebearing hyphae. Spores in sporangium clear, coenocytic hyphae.

‣Syncephalastrum‣surrounding the very dark central structure (A) are numerous small, almost clear projections (B). Each of these individual structures is a sporangium and each contains from 3 to 5 sporangiospores‣ broad, clear, nonseptate hyphae. Spores in many slender saclike structure (sporangia) adhere to a swelling on the terminal end of the hypha

‣Penicillium‣the spores of penicillium are very small, ie 3-5 microns. They are borne in long chains, thus giving the appearance of a brush‣small round spores borne in a brush like formation.

‣Geotrichum‣Hyphae break into individual cells known as oidia which are capable of floating through the air and thereby disseminating the organism‣note hyphae breaking into arthrospores. May be confused with Coccidioides immitis.

‣Aureobasidium (Pullularia)‣it is characterized by the presence of clear hyphae (A) and dark brown (dematiaceous) hyphae.‣mixture of dark, thick walled, large hyphal cells and clear spores which seem to be budding.

‣The dark (brown or dematiaceous) body (A) is a spore sac called an Ascocarp it is larger than sporangium (300 to 500 microns in diameter) and it has a very tough, thick outer wall. Excuding from this large, fruiting structure are many big, slender, saclike structures (B) which are asci. Inside each ascus are 4 to 8 ascospores.‣Ascospores

‣(A) are held in an ascus by a very fine membrane (B). Because ascospores arise from meiosis, there are usually 4 to 8 in each ascus.

Classification of Fungi (Mycetes)PSEUDOMYCETES (False Fungi)‣Schizomycetes

‣are not fungi but higher forms of bacteria which produce diseases that are clinically similar to fungal diseases‣belong to the Actinomycetes‣facultative or obligate anaerobes

‣Actinomyces israelli‣Actinomyces bovis‣Actinomyces odontolyticus‣Actonomyces viscosus

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‣all aerobic related to Mycobacteria in their acid fast property

‣Nocardia asteroides‣Nocardia brasiliensis‣Nocardia otitidiscaviarum (caviae)‣Actinomyces madurae‣Actinomyces pellitierii

‣Nocardia minutissimum‣causative agent of erythrasma

‣Nocardia tenuis‣causative agent of trichomycosis axillaris

‣Myxomycetes‣slime molds‣nonpathogenic

EUMYCETES (True Fungi)Nonseptate Fungi‣Phycomycetes

‣sexual spores (ss): zygospores‣asexual spores (as): chlamydospores

Septate Fungi‣Ascomycetes

‣ss: ascospores‣as: conidiospores

‣Basidiomycetes‣ss: basidiospores‣as: none

‣Fungi Imperfecti‣ss: none‣as:

‣conidiospores‣arthrospores‣chlamydospores‣blastospores

Infectious Mycotic DiseasesSuperficial‣Dermatomycosis - dermatophytes

‣Genus Microsporum‣Genus Epidermophyton‣Genus Trichophyton

‣Ptyriasis Versicolor - Malazzezia furfur‣Tinia nigra - Cladosporium werneckii‣Piedra

‣white - Trichosporum (beigelli) cutaneum‣black - Piedraia hortai

‣Otomycosis‣Aspergillus‣Mucor‣Penicillium‣Rhizopus

‣Keratitis - localized in eyes‣Fusarium‣Aspergillus‣Curvularia‣Penicillium‣Cephalosporium‣Candida species

Subcutaneous‣Sporotrichosis - Sporothrix schenckii‣Chromomycosis or Chromoblastomycosis

‣Phialophora verrucosa‣Fonsecae pedrosoi‣Cladosporium carrioni

‣Mycetoma or Maduromycosis‣Actinomycotic

‣Actinomadurae‣Nocardia‣Streptomyces

‣Eumycotic (True fungi)‣Allescheria or Petriellidium‣Madurella‣Phialophora

‣Entomopthoromycosis

‣Basidiobolus ranarum‣Conidiobolus coronatus

‣Lobomycosis - Lacazia loboi (Loboa loboi)‣Rhinosporidiosis - Rhinosporidium seeberi‣Phaeohypomycosis

‣Wangiella sp.‣Exophialia sp.‣Cladosporium sp.‣Hormodendrum sp.‣Dreschlera sp.

Deep Seated or Systemic‣Coccidioidomycosis - Coccidioides immitis‣Histoplasmosis - Histoplasma capsulatum‣North American Blastomycosis - Blastomycosis dermatidis‣South American Blastomycosis - Paracoccidioides brasiliensis

Oppurtunistic‣Candidiasis - Candida albicans‣Cryptococcosis - Cryptococcus neoformans‣Aspergillosis - Aspergillus fumigatus‣Zygomycosis (Mucormycosis) Phycomycosis

‣Rhizopus‣Mucor‣Absidia‣Basidiobolus‣Conidiobolus

‣Geotrichosis - Geotrichum candidum‣Penicillosis - Penicillum sp

Disease Infectious Particle

Source of Etiologic

agent

Portal of Entry

Dermatophytosis hyphae soil, animal, other human

contaminated materials

skin, hair, nails

Aspergillosis spores soil saprophytes respiratory tract

Blastomycosis microconidia soil saprophytes respiratory tract

Candidiasis yeast cells endogonous ---

Chromomycosis dematiaceous hyphae and

conidia

soil saprophytes pumcture wound

Coccidioidomycosis arthrospores soil saprophytes respiratory tract

Cryptococcosis yeast cells without hyphae

soil saprophytes respiratory tract

Histoplasmosis microconidia soil saprophytes respiratory tract

Mycetomas hyphae, spores

soil saprophytes puncture wound

Phaeohypomycosis Dematiaceous hyphae and

conidia

soil saprophytes puncture wound

Phycomycosis hyphae, spores

soil saprophytes puncture wound

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Disease Infectious Particle

Source of Etiologic

agent

Portal of Entry

Rhinosporidiosis --- possibly water skin?

Sporotrichosis hyphae, spores

plants puncture wound

Six Major Ways That Fungi Grow in Tissue

Fungus Form

Description Disease

Hyphae (A) septate, 4 to 5 microns in diameter(B)dichotomously branched(C)coenocytic 8 to 5 microns in diameter(D)dermatiaceous, septate

DermatophytosisOtomycosis

Aspergillosis and mycotic keratitis

Phycomycosis

Phaeohypomycosis

Yeast cells (A)small, 2 to 4 microns intracellular(B)encapsulated(C)broad based bud(D)multiple buds(E)long, slender, cigar-like (not seen in human tissue)

Histoplasmosis

CryptococcosisBlastomycosis

ParacoccidioidomycosisSporotrichosis

Granules largem variously colored (o.5 to 2.0 mm)

Mycetomas

Spherules (A) up to 60microns in diameter(B)up to 300 microns in diamtere

Coccidioidomycosis

Rhinosporidiosis

Fission bodies dematiaceous, 5 to 15 microns in diameter, no buds, no hyphae

Chromomycosis

Yeast cells and Hyphae

budding yeast cells and pseudohyphae

Candidiasis

*the following text are description of pictures included in the powerpoint.Hyphae‣can be coenocytic, septate, very fine, hyaline or dematiaceous‣Aspergillosis

‣dichotomous branching of the hyphae (5-10microns)‣branched septate hyphae (4-5 um)

‣Phycomycosis‣coenocytic hypahe (diameter < 10 microns)‣large (10-30 um), nonseptate hyphae often seen penetrating the lumen of blood vessels

‣*pic* KOH prepration of sputum, phase contrast Rhizopus sp. showing fragmented portions of nonseptate hyphae of varying size‣Cladosporiosis or Phaeohyphomycosis

‣brown color of the hyphae in the unstained preparation of pus from a brain abscess

Yeast Cells‣Histoplasma capsulatum

‣histopathology seciton of the node stained with hematoxylin and eosin‣yeast cells inside the cell‣numerous small (2-5um) intracellular yeast cells

‣Cryptococcus neoformas‣yeast cells surrounded by a huge, clear capsule

‣only pathogenic encapsulated yeast‣Cryptococcsis

‣budding yeast cells surround by clear capsules (KOH method)

‣Blastomycosis dermatitidis‣ yeast cells is 8-15 microns in diameter and the bud being formed on the parent cell is attached with a broad based neck (Broad based bud)

‣Paracoccidioides brasiliensis‣outstanding characteristic of the yeast cells is that they multiply by forming numerous small buds‣multiple budding

‣Sporothrix schenckii‣darkly stained gram positive yeast cells are long and slender‣round, oval, or “cigar-shaped” yeast cells

Granules‣tightly packed masses of hyphae or filaments which are surrounded by a tough outer rind‣may be grossly visible, 0.5-10mm, in diameter‣microscopically, they contain either fine and delicate filaments or thick and septate hyphae‣Actinomycotic granule

‣large, lobulated structure‣usually from Actinomycotic mycetoma‣contain filaments less than 1cm

‣Eumycotic granule‣large and surrounded by a very thick rind which may be variously colored‣Madura foot or Maduramycosis‣large granule up to 2mm‣contain septate hyphae, 3-5um

Sporangia or spherules‣large,sac-like structures which fill with spores as they mature‣sporangiospores or endospores - spores contained in these sacs‣Rhinosporidiosis

‣spherical, darkly stained structures, in the middle are sporangia

‣Coccidioidomycosis‣contains numerous sporangiospores and 2 larger sporangia which are empty‣20-60 um containing endospores, 5-10um

Fission Bodies or sclerotic bodies‣spherical, dematiaceous structures which neither bud nor produce hyphae‣division is by splitting down the middle‣Chromomycosis

‣fission bodies or sclerotic bodies are dematiaceous, does not have any buds and appears to be dividing by fission‣round, thick walled brown cells 5-15um

Yeast Cells and Hyphae‣Pulmonary candidiasis

‣abundant gram positive hypahe and few yeast cells‣Candidiasis

‣darkly stained pseudohyphae mixed with yeast cells

_____________________________________________________transcribed by Howard Reyes-Lao, Mark TuD Nxt Generation MD 2010

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