View
236
Download
10
Category
Tags:
Preview:
Citation preview
Claudio Cortes M. D.V.M., Ph.D
Medical Microbiology and ImmunologyThe University of Toledo3000 Arlington Avenue, mail stop 1021Toledo OH, 43614419.383.6386Email: claudio.cortes@utoledo.edu
Contact information
Medical Mycology
SUBJECT CLASS
Introduction: Fungal structure and growth 1Fungal physiology and antifungal 2Subcutaneous pathogens 3Cutaneous pathogens (Dermatophytes) 4Opportunists- Mycoses I 5Opportunists- Mycoses II 6
“Septate hyphae, intercalary and terminal chlamydospores with rare microconida along hyphae branches were identified. Multiple small budding yeast around a big one was found in BAL sample. Diagnostic: Dimorphic fungi Paracoccidiodes brasiliensis”
OBJECTIVES To impart sufficient basic knowledge about
the growth of Fungi. Terminology
Distinguish structures/components of several forms of fungi
Assist you in diagnosing mycotic diseases.
Topics
1. Fungi characteristics
2. Fungal growth
3. Structures (naming fungi)
4. Fungi and disease
What are fungi?
1. Characteristics of fungi
HIV
16S rRNA
Fungi closer to animals than to plants
Pneumocystis carinii (renamed Pneumocystis jiroveci)
Eukaryotes
Fungi are heterotrophic (non-photosynthetic) Do not contain chlorophyll
Fungal cell membrane have a unique sterol. Ergosterol
Cell wall similar in structure to plants. Differs in chemical compositions Chitins biosynthesis
Characteristics of fungi cont.
Fungi digest then ingest Exoenzymes
Vegetative body may be unicellular (yeasts)
or composed of microscopic thread called
Hyphae (singular Hypha)
Reproduce by means of spores, usually
wind-disseminated Sexual (meiotic) and asexual (mitotic) spores may be
produced.
Characteristics of fungi
Viruses 0.08 mBacilli 4-6 mCocci 0.8 mSpirochetes 8 - 10 mProtozoa 15 mFungi 5 – 15 mNematodes 10 mm
SIZE COMPARISON OF PATHOGENS
Why study fungi?
EnvironmentSaprophytic role (decomposer)
Complex enzymatic machineryPlant and Fungi (mutualism)
Food Truffles, morels, mushroom, puffballs Cheese (Penicillium species) Soy products (Aspegillus, Rizhopus) Alcohol (Saccharomyces)
Bioremediation
Economy
Industry (pharmaceutical) Antibiotic/drugs
Penicillin (Penicillium notatum). Alexander Fleming. Cephalosporins (Acremonium = Cephalosporium) Cyclosporins -> immunosuppressant.
Medicine Mycotoxicosis (toxic fungi)
Mushroom poisoning Pre-formed toxin
Mycotoxins Production of toxin
Fungal toxins produced during infection Ethanol Oxalic acid
Allergies, Hypersensitivities and Chronic lung disease (often occupational)
FARMER’S LUNG – Moldy hay MALT WORKER’S DISEASE – Moldy barley CHEESE WASHER’S LUNG – Moldy cheese WOOD TRIMMER’S DISEASE – Moldy wood
Infection
2. Fungal growth
A B
The basic units of growing fungi
Yeasts Hyphae (mold)
Yeasts Single cells dividing usually by budding (single nucleus) Reproduce by budding (or by fission in some groups) Found where there is plenty of moisture (spread in water
films and by turbulence). Yeast cannot push into substrates as do hyphae. Growth in the form of yeasts is quite common for many
human pathogens. Growth of the organism within phagocytes and for easy
hematogenous spread. Cause cutaneuos candidiasis (AIDS), systemic mycosis
(hospitalized patients), and vaginal yeast infection
A B
Mold growth Long filaments growing at apex branching. (sing. Hypha): Mold Apical growth
Hyphae branch to form mycelium Mycelium (plural mycelia) Push into substrates
Common in cutaneous and subcutaneous infection Ringworm-> Dermatophytes
www.myhome.cortes.comMYCELIUM
www.rhodes.edu/biology/hill/hill/ResearchBackground.html
Classification based on cell division(hyphae)
Septate (with septa) Aspergillus and many other species have septate
hyphae. Septate hyphae with acute-angle branching important in pulmonary disease caused by Aspergillus spp.
Aseptate or coenocytic (without septa) Non-septate hyphae are associated with Mucor, some
zygomycetes, and other fungi.
Septate Aseptate
Classification based on fungal growth
Yeast
Mold
DIMORPHIC FUNGI
Growing both in the form of a yeast and a mold Common in systemic fungal infection The environment determines their morphology.
Temperature, CO2, nutrients This conversion is associated with a change in cell
wall composition. Complete reversal of a morphological change follows
return of the fungus to the initial environment.
37°C25°C
DimorphicYeast Mold Uncertain
Histoplasmosis
Coccidioidomycosis (Valley fever)
Blastomycosis (N. American blastomycosis)
Paracoccidioidiomycosis (S. American
blastomycosis)
Penicilliosis
Sporotrichosis(Rose-thorn or rose-gardeners)
Classification based on growth
Candida spp Dermatophytes
Aspergillus
Zygomycetes
Fusarium
Dematiaceous fungal infections (Trauma) - Cromoblastomycosis (Dermatitis verrucosa) - Phaeohyphomycosis
Mycetomata (Madura foot) (tumor like presentation)
Pneumocystis jiroveci (AID): Cysts
Lacazia loboiCryptococcus neoformans
3. Structures of Fungi
Naming fungi
Naming fungi Hyphae and Septa
Little variation Sporulation structures and spores
Variable and are basis of most identifications
Increasingly rRNA gene sequencing is being applied
Spores Many forms of spore production -> allow fungal identification Spores allow fungi to spread to novel sites.
Conidiospores/conidia (conidiophores)
Blastic conidiogenesis
Aspergillus, Penicillium, candida
Thallic conidiogenesis
Dermatophytes (Microsporum)
Coccidioides immitis (arthospores)
Naming fungi cont.
Ascospores (Ascus)Basiodiospores (Basidium) Zygospores (Zygosporangium)
Sporangiospores (sporangium; sporangiophore)
Zygomycetes
Asexual forms(Anamorphs)
Sexual forms (Teleomorph)
Conidiospores (conidia) Blastic conidiogenesis
where the spore is already evident before it separates from the conidiogenic hypha
Blastoconidia are pushed out of conidiophore (specialized structure). New wall is formed as the conidium balloons out.
Penicillium, Aspergillus, Fusarium, Stachybotrys, Trichoderma, Candida albicans, etchttp://www.mycolog.com/CHAP4a.htm
Asexual forms(anamorphs)
Conidiophore
ConidiaConidiospore
Conidiospores (conidia)
Blastic conidiogenesisi.e Penicillium Marneffei
Thallic conidiogenesis (Spores produced by modifying an existing hypha. Wall is remodeled.)
Dermatophytes (Microsporum canis)
Systemic mycosis Dimorphic;Coccidioides immitis
Asexual forms(anamorphs)
Macroconidium
arthospores
Sporangiospores (sporangium; sporangiophore) Spores produced following cytoplasmic cleavage within a
sporangium. Zygomycetes -> zygomycosis
sporangiophore
sporangiosporessporangium
Asexual forms(anamorphs)
• Ascospores -> ascomycetes (ascus sing = asci plural)
• Basidiospores produced Basidiomycetes
• Zygospores produced by zygomycetes**
Basidium
Sexually produced spores (teleomorph)
Sporangium
Zygosporangium
Sporangiophore
Sexual reproduction(Zygospores)
Asexual reproduction by spores(Sporangiospore)
Meiotic during
Germination
Fertilization
Life cycle of black bread mold (Rhizopus stolonifer)
zygomycetes
Biology of plant 5th edition. Raven PH. 1992
Naming yeasts Often little morphologic differences
Yeasts grouped by morphology,
pigment and how they divide, then
put into distinct species on basis of
a metabolic profile.
Most features of metabolic profile
associated with different patterns
of sugars and forms of nitrogen
(nitrate, nitrite, ammonium etc)
used
DNA sequencing coming on fast
Spores Many forms of spore production -> allow fungal identification Spores allow fungi to spread to novel sites.
Coccidioides
Conidiospores/conidia (conidiophores)
Blastic conidiogenesis
Aspergillus, Penicillium,
Thallic conidiogenesis
Dermatophytes (Microsporum)
Coccidioides immitis (arthospores)
Naming fungi cont.
Ascospores (Ascus)Basiodiospores (Basidium) Zygospores (Zygosporangium)
Sporangiospores (sporangium; sporangiophore)
Zygomycetes
Asexual forms(Anamorphs)
Sexual forms (Teleomorph)
Fungi and disease
Species of Fungi
>1,000,000 species
~400 pathogenic
Subcutaneous Mycoses
Chromomycosis
(Dermatitis verrucosa)
Mycetoma (actinomycetes)
(Madura foot)
Sporotrichosis*
(rose-thorn or rose-
gardeners' disease)
Cutaneous Mycoses
Systemic Mycoses
Opportunistic fungi
Dermatophytes
Athlete’s foot Jock itch Ringworm diseases
Cutaneous candiadiasis*
Candida: patients with AIDS
Histoplasmosis (Darling’s
diseases)Coccidioidomycosis
(Valley fever)Blastomycosis
(North American blastomycosis)
Paracoccidioidiomycosis (South
American blastomycosis)
Penicilliosis
Sporotrichosis *
Candidiasis *
Aspergillosis,
Pneumocystosis,
Zigomycosis
Cryptococcosis.
Classification Mycosis diseases
Skin, hair and nails.
Rarely invade deeper tissue
Subcutaneous tissue
Rarely spread systemically
May become widely disseminated.
Predilection for specific organs
Ubiquitous saprophytes
Predisposing diseases/condition
Involve skin and deep viscera
Cutaneous Mycoses
Skin, hair and nails Rarely invade deeper tissue
Dermatophytes Athlete’s foot or tinea pedis Jock itch or tinea cruris Ringworm diseases (tinea corpora, faciei, capitatis,
manuum, unguium) Cutaneous candiadiasis
Skin and mucosal; Oral thrush and Candida esophagitis, are extremely common in patients with AIDS.
Subcutaneous Mycoses
Subcutaneous tissue and rarely spread systemically. The causative agents are soil organisms introduced into the extremities by trauma
Chromomycosis (dermatitis verrucosa)
Mycetoma (Madura foot)
Sporotrichosis (rose-thorn or rose-gardeners' disease)
Systemic Mycoses Involve skin and deep viscera May become widely disseminated Predilection for specific organs
Histoplasmosis (Darling’s diseases) Coccidioidomycosis (valley fever, San Joaquin Valley fever,
California valley fever, and desert fever) Blastomycosis (North American blastomycosis) Paracoccidioidiomycosis (South American blastomycosis” and
"Paracoccidioidal granuloma”) Penicilliosis (south Asia) Systemic candidiasis (Hospital)
Opportunistic fungi Ubiquitous saprophytes and occasional
pathogens that invade the tissues of those patients who have: Predisposing diseases:
Diabetes, cancer, leukemia. Predisposing conditions:
Genetic disorders (cystic fibrosis), Agammaglobulinemia, steroid, contraceptive pills or antibiotic therapy, transplantation.
Aspergillosis, Candidiasis, Pneumocystosis, Zigomycosis, Cryptococcosis.
Diagnosis of fungal infections
Clinical recognition
Case HistoryPhysical examinationOrgan Imaging
Laboratory SpecimenSkin and nail scraping, urine, sputum, BAL, blood Pleural fluid, Peritoneal fluid, tissue biopsies.
Direct MicroscopyHistopathology
Culture and identification
Serodiagnostic testWet Mount (10 % KOH)
Biopsy
DNA probesPCR
Skin test (Dermal Hypersensitivity)
Dimorphic fungi
(systemic)
Histoplasmosis (Histoplasma capsulatum) Lungs, mucocutaneous, pericarditis. Grows in soil and material contaminated with bird or bat
droppings. The Central River Valleys in the midwestern and south
central United States are endemic for histoplasmosis. Latin America, part of Asia, Europe, Middle East, Africa.
Inhaled conidia (spores) small, intracellular, budding yeast
Tuberculate conidia(240C)
Yeast(370C)
YeastTissue
Penicillium Marneffei Prominent mycotic pathogen among HIV-infected individual. Southeast Asia. Imported cases in USA and Europe. Lung, lymphadenopathy, hematogenous dissemination. Intracellular (like Hisptoplasmosis). Inhaled conidia convert to yeast form with transverse
septa.
Mold: Conidia and red pigments
Yeast transverse septa.
Coccidioidomycosis (Coccidioides immitis) California valley fever
Desert soil. Southewestern USA, Mexico, region of Central and South America
Lung. CNS, bones and joins. Cutaneous infection Inhaled arthroconidia convert to spherules (contains
endospores).
arthroconidia Spherules with endospores
Blastomycosis (Blastomyces dermatitidis) “North American blastomycosis”
Lung and skin Soil and organic debris USA OHIO-Mississippi River Valley. North-America Inhaled conidia convert to large broad-based, budding
yeast.
Yeast (budding broad-based)Conidia
Paracoccidioidomycosis
(Paracoccidioides brasiliensis) South American blastomycosis," and "Paracoccidioidal
granuloma” Chronic single or multiples organs involvement Lungs, mouth, nose, lymph nodes Inhaled conidia convert to multipolar budding yeast
Multiple small budding yeast around a big one(Pilot wheel) (370C)
Septate hyphae, and terminal chlamydospores (240C)
Subcutaneous mycosis
“Rose-thorn or rose-gardeners” Lungs, joints, bones, and even the brain. Nodules and ulcers along lymphatics at site of
inoculation (Lymphatic nodules) Peru, tropical places, USA. Zoonotic Inhaled conidia covert to yeast Systemic mycosis (rare)
Swollen conidiophores, tear shaped, round conidia, sleeve shapes, rosette form
(240C)
Yeast/cigar shape(370C)
Sporothrichosis (Sporothrix schenkii)
Opportunistic fungi
Aspergillosis(A. fumigatus, A. niger, A. flavus and A. clavatus )
Ubiquitous molds found in organic matter Lungs Immunocompromised-> Systemic Inhaled conidia Hyphae (in lungs) England, USA Neutropenia Acute angle branching (<45oC)
methenamine-silver–stained tissue section of lung. (Figure courtesy of The Geraldine Kaminski Medical Mycology Library,
produced by David Ellis and Roland Hermanis, Doctorfungus Corporation. http://www.doctorfungus.org/imageban/index_enlarge.pl.)
Zygomycosis Ubiquitous molds
Lungs, skin Immunocompromised-> Systemic Inhaled conidia Hyphae England, USA Aseptate hyphae Diabetes Sinus involvement
Cutaneous mycosis
Epidermophyton
Microsporum
CandidaTrichophyton
Check figure 73-1. Medical microbiology.
Arthoconidia (thallic)
chlamydospores
Tuberculate conidia
microconidia
END
Overview of medically important fungiGroup (criteria
based on Morphology and
disease Disease Etiologic agentDiagnostic in vivo form
Diagnostic in vitro form Natural habitat
1. Molds Chromoblastomycosis Cladosporium Chestnut brown Branching chains of Woody plantBlack fungi carrionii thick-walled single-celled conidia material
Unifomr cells 10 um in diameter
Fonsecaea Same Series of single- Samepedrosoi celled conidia
giving rise to seriesof secondary conidia
Phaeohyphomycosis Exophiala Hyaline to brown Single-celled conidia Woody plant materialjeanselmei yeast-like cells, in balls at the apices
filaments, septate of annellideshyphae, in variouscombinations
Wangiella Same Single-celled conidia Soil and similar ambientsdermatitidis in balls a thte apices
of phialidesand annellides
Xylohypha Brown septate Sparsely branched, bantiana Hypahe long chains of
single-celled conidia
Overview of medically important fungiGroup (criteria
based on Morphology and
disease Disease Etiologic agentDiagnostic in vivo form
Diagnostic in vitro form Natural habitat
1. Molds Chromoblastomycosis Cladosporium Chestnut brown Branching chains of Woody plantBlack fungi carrionii thick-walled single-celled conidia material
Unifomr cells 10 um in diameter
Fonsecaea Same Series of single- Samepedrosoi celled conidia
giving rise to seriesof secondary conidia
Phaeohyphomycosis Exophiala Hyaline to brown Single-celled conidia Woody plant materialjeanselmei yeast-like cells, in balls at the apices
filaments, septate of annellideshyphae, in variouscombinations
Wangiella Same Single-celled conidia Soil and similar ambientsdermatitidis in balls a thte apices
of phialidesand annellides
Xylohypha Brown septate Sparsely branched, bantiana Hypahe long chains of
single-celled conidia
Overview of medically important fungi (cont.)Group (criteria
based on Morphology and
disease Disease Etiologic agentDiagnostic in vivo
formDiagnostic in
vitro form Natural habitat3. Dimorphic Blastomycosis Blastomyces Round to oval Small, round, smooth Woody plants
dermatiditis yeast s 8-15 um in diameter single-celled conidia materialhaving broad-based budded daugther cells
Coccidioidomycosis Coccidiodes Spherules 30-60 um Alternating barrel Soilimmitis containing single-celled shaped arthroconidia
endospores 2-5 um in diameter2.5 - 4 by 3-6 um
Histoplasmosis Histoplasma Oval, intracellular yeasts Tuberculate macro- Soil enriched by bat, starling capsulatum 2-5 - 3.5 um in diameter microconidiaconidia and smooth- or chicken droppings
walled
Paracoccidioidomycosis Paracoccidioides Multiples budding yeast, roundTypically sterile Probably woody plantsbrasiliensis budded cells
2-10 um attached to mature cells30-60 um in diameter
Sporotrichosis Sporothrix Round to oval yeast 3-5 Conidia develpoing Woody plant materialschenckii um in diameter from sympodial
conidiophores and fromthe hyphae
4 Oportunistic Aspergillosis Aspergillus Septate, dichotomously branchingChain of conidia Sameinfections favus hypahe 2.5 - 3.5 um in from phialides
diameter Same
Aspergillus Samefumigatus Usually sterile, some
isolate from phialidesMycetoma Madurella granules in tissue and draining
mycetomatis sinuses
Overview of medically important fungi (cont.)Group (criteria
based on Morphology and
disease Disease Etiologic agentDiagnostic in vivo form
Diagnostic in vitro form Natural habitat
2. Dermatophytes Tinea capitis Microsporum Hyphae in scaly Macro- and micro- Animals (zoophilic)canis erythematous conidia Kittens/dogs
lesions, arthroconidia within and around hair(ectothrix)
Thrichophyton Hyphae in scaly Conidia of varios Human (anthropophilic)tonsurans erythematous sizes and shapes
lesions, arthroconidia within hair(endothrix)
Tinea corporis Microsporum Hyphae in stratum Macro- and micro- Soil (geophilic)gypseum corneum conidia
Trichophyton Same Same Humans and othermentagrophytes animals (rodent, rabbits,etc)
Trichophyton Same Same Humansrubrum
Tinea cruri/pedis Epidermophyton Hyphae in stratum Club-shaped conidia Humansflloccosum corneum
Tinea cruri/pedis/ungium Trichophyton Same Macro- and micro- Humans and otherinterdigitale conidia animals(mentagrophites)
Tinea cruri/pedis/ungium Trichophyton Same Same Humansrubrum
Cell wall composition and taxonomic classification of representative medically important fungi
Principal cell wall polymer Taxonomic Group Examples
Chitin-chitosan Zygomycetes Rhizopus arrhizus
Chitin-glucan Ascomycetes (mycelial) Pseudallescheria boydii
Basidiomycetes (mycelial) Schizophyllum commune
Glucanmannan Ascomycetes (yeast) Sacchamomyces cerivisea
Chitin-mannan Fungi imperfecti Candida albicans
Basidiomycetes (yeast) Filobasidiella neoformans
Hair Perforation Test
Urease Test
Growth at 37°C
Macro-conidia Micro-conidia Distinguishing Characteristics
Trichophyton rubrum
Negative Negative Positive Pencil shaped/cigar shaped
Club shaped to pyriform, along the sides of the hyphae
Red reverse pigmentHair perf. test neg.
Club shaped microconidia
Trichophyton mentagrophytes
Positive Positive Positive Club shaped when present
NumerousUnicellular to round in grape like clusters
Round microconidia in grape like clusters Spiral
hyphae
Trichophyton tonsurans
Usually (-)Occasionally +
Positive Positive Cylindrical to cigar shaped and sinuous,
if present
Numerous, varying in shape and size, club shaped to balloon
shaped
Microconidia varying in shape and size
Growth enhanced by thiamine
Trichophyton verrucosum
Negative Negative Positive “Rat-tailed” if present
Rare or Absent Chlamydospores in
chains typically seen
Chlamydospores in chainsGrowth better on media
with thiamine and inositol
Trichophyton terrestre
Positive Positive Negative 2-8 celled borne at right angles to
hyphae
Club shaped with squared-off base on
pedicels
Microconidia with squared-off base on short pedicels
Epidermophyton floccosum
Negative Positive Positive Club shaped, often in clusters
Absent Khaki colored colony with brown reverse
Microconidia absent
Microsporum canis
Positive Positive NA Fusoid, thick, rough walled with
recurved apex
Typically absentClub shaped if
present
Fusoid, rough walled macroconidia with
recurved apex
Microsporum gypseum
Positive Positive NA Ellipsoidal to fusiform, thin, Rough walled
Moderately abundant Club shaped
Thin walled macroconidiaTawny-buff granular
colony
Microsporum nanum
Positive Positive NA Typically 2 celled Pear or egg shaped
Rough walled
Clavate when present 2 celled pear shaped macroconidia
Pathogen Fungal ligand(s) Phagocytic receptor(s)
Aspergillus fumigatus Mannans, B-glucans DC-SIGN, dectin-1
Blastomyces dermatitidis BAD1 CR3, CD14
Candida albicans Mannans, B-glucans DC-SIGN, dectin-1
Coccidiodes posadasii Mannans, B-glucans DC-SIGN, dectin-1
Cryptococcus neoformans Glucoronoxylomannan TLR2, TLR4, CD14, CD18, FcyRII
Histoplasma capsulatum HSP60 CD18, VLA-5
Pneumocystis jiroveci Mannans, B-glucans DC-SIGN, dectin-1
Definitions and Nomenclature http://labmed.ucsf.edu/education/residency/fung_morph/fungal_site/
page1.01.html#cleistothecia
Anamorph
Asexual or "imperfect" form of a fungus; for example, Scedosporium apiospermum is the anamorphic form of the teleomorph Pseudallescheria boydii
Arthroconidia
Conidia arising from pre-existing cells in the mycelium; adjacent cells collapse to release the mature form; see, for example, Geotrichum and Coccidioidomycosis
AscosporeSexual spore produced in a sac-like structure called an ascus
BlastoconidiaOne of three types of vegetative "spore" arising directly from the vegetative mycelium; budding form, e.g. seen in yeasts
ChlamydoconidiaConidia arising from pre-existent cells in the hyphae, which thicken and enlarge; may be intercalary, sessile, or terminal
ColumellaThe swollen, dome-shaped tip of a sporangiophore that extends into the sporangium
Conidia(singular conidium) Asexual "spores" of fungus
ConidiophoreSpecialized hyphal element bearing conidia
HolomorphTaxonomic name including teleomorphic and anamorphic forms of a fungus; the name of the teleomorph also serves as the name of the holomorph
Hyphae(singular hypha) The fundamental, threadlike structure of molds
Metula(plural metulae) Structure below the phialide in some Penicillium and Aspergillus species; see for example Aspergillus terreus
Mycelium(plural mycelia) The mass of filaments that constitutes the body of a mold; may be vegetative or aerial (reproductive)
Phialide
A conidiogenous cell that produces conidia from within its apex, which does not increase in width or length during conidiogenesis
Rhizoid
Root-like, branched hyphae which usually extend into growth medium; found especially in Zygomycetes. See, for example, Rhizopus
Sporangia
A fruiting body which forms a closed sac; see, for example, Absidia , Rhizopus
SporangiophoreA specialized hyphal element that bears the sporangium
StolonHorizontal hyphae growing along the surface of growth medium; runner
TeleomorphSexual or "perfect" form of a fungus; see Anamorph and Holomorph, above
Recommended