🥇Medical Mycology (ALL) Flashcards
The term “mycology” is derived from Greek word “mykes” meaning?
mushroom
2 Basic Fundamental Structures of fungi
Hyphae
Spores
Fungi are achlorophyllous meaning what?
can not manufacture its own food
T/F
Fungi grow I the presence of acid and large amount of sugar (SDA- with pH of 5.6) which inhibits bacteria
T
2 Morphologic Forms of Fungi
Yeast
Mold
✅ They produce moist, creamy, opaque or pasty colonies 0.5-3.0 mm in dm on culture media
✅ Single-celled/ unicellular structures with a thick cell wall
✅ Most reproduce by asexual budding, few by binary fission
Yeast
Produces multicellular filamentous colonies: Fluffy, cottony, wooly or powdery
Mold
The basic structural unit of mold which can be divided in to: Septate, Aseptate, Mycelium
Hyphae
Side note:
Which can be divided into 2: a. Vegetative or Substrate b. Aerial or Reproductive mycelium
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(when hyphae overlaps one from the other), hyphae forms a mass of intertwining strands
Mycelium
3 COMMON FORMS OF HYPHAE
✅ Antler Hyphae/Favic Chandelier
✅ Racquet hyphae
✅ Spiral hyphae
- The capability of an organism to grow in more than one form under different environment
✅ Dimorphism
(Monomorphic- The opposite)
T/F
Sporothrix schenkii exhibits Dimorphism characteristics
T
derived from fusion of identical cells from the same hyphae
Zygospores/Zygomycetes
Spores enclosed in a specific sac called ascus (asci)
Ascospores/Ascomycetes
enclosed in a club-shaped structures called basidia or basidium
Basidiospores/Basidiomycetes
derived from fusion of non-identical cells from the same hyphae
Oospores
Side note:
Asexual (anamorph) = imperfect fungus (Fungus imperfecti)
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Buds formed by budding process, sprouting from the surface of the parent cell
Blastospores
Ex. Candida albicans
Cryptococcus neoformans
derived from the cells of the thallus or body of the fungi
Thalospores
Arise by fragmentation of the ends of hyphae at the point of septation; square barrel-shaped thick walled cells
Arthrospores/Arthroconidia
When hyphal cells separate from one another to form flat ended spores
✅ Oidia
Example:Geotrichum candidum
Enlarged, round unicellular thick-walled structures that are formed during unfavorable conditions; formed by the enlargement of a hyphal cell
Chlamydospores/Chlamydoconidia
3 types of Chlamydospores
TIS
✅ Terminal
✅ Intercallary
✅ Sessile
Born internally within a sac called “SPORANGIUM”, which develops at the tip of the sporangiophore
Sporangiospores
Asexual spores produces singly or in groups (en-grape) by specialized vegetative strands/branch called Conidiphore (borne externally not with in)
Conidia
NOTE:
Some conidiophore terminate into swollen structure called VESICLE; From the surface of the vesicle are formed secondary flask-shaped or bottle called PHIALIDES or STERIGMA which in turn give rise to long chains of conidia as seen in Aspergillus
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2 Sized of Conidia
✅Microconidia/Microaleuriospores
✅Macroconidia/Macroaleriospores
(3) DIAGNOSTIC METHODS USED FOR FUNGAL IDENTIFICATION
✅ Direct Examination
✅ Fluorescence
✅ STAINING
NOTE:
✅ KOH (10-20%) Wet mounts
* Observe for: hyphae, budding yeast cells or any mycelial filaments
✅ India Ink
— For identification of Cryptococcus neoformans .
— Look for encapsulated yeast cells
Ideal specimen
CSF (meningeal form)
Sputum (pulmonary form)
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3 Direct Examination methods
✅ KOH (10-20%)
✅ India Ink
✅ Lactophenol Cotton Blue (stain used is AMAN Medium - Observe for spores, yeast cells and hyphae)
Best staining for visualizing fungi in skin scraping or tissue If dematiaceous, appears as dark brown/black
PAS staining
Gridley, Gomori-Methenamine Silver
Excellent for STAINING yeast cells of H. capsulatum in TISSUE
Wright’s Stain or Giemsa
Best stain for B. dermatitidis
Papanicolau method
Stain ideal for T. versicolor
Acridine Orange
Useful in the differentiation of Nocardia from Actinomyces Hyphae of Nocardia steroids and Nocardia brasilliensis are partially acid fast
Acid Fast Stain (Kinyoun)
NOTE!!!
Recommendation for Fungal Culture Media
✅1. Media with or without enrichment should be used (5-10%) sheep’s RBC
✅ 2. Media with or without cyclohexmide (inhibits growth of fungi) should be used
✅ 3. All should contain antibacterial agents like chloramphenicol
✅ Culture should be incubated at RT for 30 days before reporting negative
✅ Culture should be examined at least 3 times a week during incubation
✅ Recommended to use agar plates or screw capped tubes for the recovery of fungi
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NOTE!!!
Disadvantage of Culture Tubes:
✅ This will lead to poor isolation of colonies
✅ Reduce surface area of culture
✅ Tendency to promote anaerobiasis
✅ Cotton plugged tubes with culture media are not ideal or unsatisfactory for fungal cultures
Serologic Test for Fungal Detection
✅A significant rise in antibody titer to confirm the diagnosis
✅Complement fixation= for Cocciioidomycosis, Histoplasmosis, Blastomycosis 2. Latex Agglutination= for Cryptococcosis
✅ Precipitation test
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Fungi has a rigid cell wall made of?
chitin
…..which may be layered with mannans, glucans and other polysaccharides in association with polypeptides.
NOTE!!!
🩵Some lower fungi possess cellulose in their cell wall. Some fungi such as Cryptococcus and yeast form of Histoplasma capsulatum possess polysaccharide capsules that help them to evade phagocytosis.
🩵Inner to the cell wall is the plasma membrane that is a typical bi-layered membrane in addition to the presence of sterols.
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Fungal membranes possess______ in contrast to cholesterol found in mammalian cells.
ergosterol
Type of mycoses that is - Limited or confined to the outermost layer of the skin, hair and nails
- Does not invade living tissue
SUPERFICIAL MYCOSES
✔Profuse sweating
✔ Poor hygiene
✔ Poor immunityPoor hygiene
✔ Poor immunity
Spaghetti and meatballs
Symptoms: Hypopigmented macules
Pityriasis versicolor
-Malassezia furfur
Black, 2-celled oval yeasts in skin scrapings
-Commonly found on the palms
-Symptoms: Black macules
Tinea nigra
-Exophilia werneckii
Black nodules on hair shaft composed of spore sacs and spores
-black nodule on hair shaft
what is the disease
Black piedra
-Piedraia hortae
White nodules on hair shaft
-creme coloured nodukes on hair shaft
White piedra
-Trichosporum beigelii
- Major cause of blindness in Asia
- White corneal plaques with the development of satellite lesions and endothelial plaques
- Etiologic agent:
✅Yeasts: Candida species
✅Filamentous fungi: Fusarium, Aspergillus, Alternaria, Curvularia, Penicillium, Mucor
✅Contact lens use: Cosmetic lens – filamentous
- Therapeutic lens – Yeasts
Keratomycosis (Keratitis/ Keratomycosis/ Keratitis)
Mode of action: inhibits CYP P450 14 a-demethylase enzyme involved in conversion of lanosterol to ergosterol
Azoles: Ketaconazole, fluconazole, Voriconazole
binds to ergosterol in fungal cell membrane & cause the membrane to
become leaky.)
Polyenes: Amphotericin B, Natamycin
causes faulty RNA synthesis & non competitive inhibitor of Thymidylate
synthesis
Pyrimidines: Flusytosine
Ergosterol Biosynthesis inhibitor
Allylamines: Terbinafine
✅ Clinical picture: Chronic fungal infection of the outer ear canal -
✅ Organism responsible: Candida albicans, Candida tropicalis
Aspergillus fumigatus, Aspergillus niger
Otomycosis/ Mycotic Otitis Externa
Etiologic agent; Piedraia hortae
- Occurs on scalp
- Microscopic appearance: 10-290% KOH- hard and black nodules resembling nits of lice
BLACK PIEDRA
Etiologic agent: Tricosporon beigelii
- Microscopic appearance: white nodules lager and softer
- Septate not dematiaceous
WHITE PIEDRA
✅ Clinical picture: Superficial infection on the palm of the hands or the sole of the foot
✅ Etiologic agent: Clasdosporium wernickii or Hortae or Exophiala or Phaeoannellomyces werneckii
✅Characteristics: 10-20% KOH: Strongly dematiaceous septate hyphae
Tinea nigra/ Keratomycosis nigricans palmaris/ Tinea nigra palmaris/Pytyriasis nigra/Microsporis nigra
🤰Clinical picture: Patchy brown desquamating rash involving mainly the trunk, arms, shoulder and face “ blotchy appearance
✅ Characteristic microscopic appearance: in 10-20% KOH
- “spaghetti and meatballs appearance”
🍝🍝🍝🏀🏀
Pityriasis versicolor
is a disease of the skin and its appendages caused by fungi.
It comprises dermatophytosis, candidiasis, and pityriasis versicolor
Superficial mycosis
NOTE!!!
Dermatophyte is responsible for most superficial fungal infection and the expected lifetime risk of getting a dermatophyte infection is between 10 and 20.
The dermatophytes are a group of closely related fungi infecting skin, hair, and nails in living host including man. They produce an infection called dermatophytosis, also known as ringworm or tinea. The skin infections caused by nondermatophytic fungi are known as dermatomycoses whereas hair and nail are known as piedra and onychomycosis, respectively.
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Disease associated:
✔ Ringworm
✔ Jock itch
✔ Athlete’s foot
✔ Dermatomycoses
- ✔ Invades the keratinized areas of the body as skin, hair and nails
CUTANEOUS MYCOSES/ DERMATOMYCOSES
Breakdown and use____ as a source of nitrogen but are usually incapable of penetrating the subcutaneous
tissues
keratin
Note:
✔ Most common fungal infection of human and are usually referred to as Tinea
✔ Outstanding feature of the etiologic agent:
✔ Keratinophilic bases on hair baiting method (Used wood’s light to detect fluorescence hair)
✔ Hair: Ectothrix = dermatophytes grow outside the hair shaft
Endothrix = dermatophytes grow inside the hair shaft
✅fungal skin infection = Tinea
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=affects the hair and skin
Microsporum
=affects the hair,skin and nails
Trichophyton
=affects the skin and nails
Epidermophyton
Note!!!
✔ Body (Tinea corporis)
✔ Scalp (Tinea capitis)
✔ Feet (Tinea pedis or athletes’s foot)
✔ Groin ( Tinea corporis or jock itch)
-✅For nails and Skin: observes hyaline, septate hyphae
The specimen for culture is taken from the center of the lesion
- Hair, skin and nail cultures use mycosel or mycobiotic medium and incubate at RT 4-6 weeks before
reporting
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Tinea unguium affects the whaT???!
Nail (Onchomycosis)
3 GENERA CAUSING RINGWORM
Microscporum - hair/skin
Trichophyton - hair/skin/nail
Epidermophyton - nail/skin
- Only fungus disease that can almost be diagnosed by clinical picture alone
- Etiologic aent: Sporothrix schenkii
- Cigar-shaped- Bodies
- ✔ Conidia borne in floral-like arrangement e conidia borne along the sides of hdaisy-like “Rossette”
clusters or “boquet”-like
Sporothricossis/Rose Gardener’s Disease
tumor-like lesions characterized as “ cauliflower-like”
Chromomycosis/Chromoblastomycosis/Verrucous dermatitidis
- Chronic granulomatous infection which produces tumor-like lesions and sinus tract formation with the presence of granules usually of the foot
- A. israelii= “molar tooth-like” colony
- Eumycotic mycetoma
✔ True fungi
Mycetuma/Madura foot/Maduramycosis
- Initial lesions are small, hard and subcutaneous nodules appearing on the extremities, face or ear
- Lymhp nodes are not involved
- Etiologic agent: Loboa loboi
Lobomycosis
✅ Tumor-like polyp usually on the nose
✅ Etiologic agent: Rhinosporidium seeberi
✅ Acquired from stagnant water
Rhinosporidiosis
causative agent
- Acquired through inhalation from bird droppings
- Etiologic agent: Histoplasma capsulatum
- Smallest yeast cells
- Emmonsiella capsulatum
✔ “INTRACELLULAR YEAST CELLS” on neutrophils - most associated with AIDS pxs
- can calcify the lungs (similar to TB)
Histoplasma capsulatum
Causative agent:
- Acquired through inhalation of arthrospores
✔ Mycellium is adherent to the agar surface in some portions of the colony “cob-web” like growth
- Microscopic features from Culture
✔ Chains of alternate ✅ BARREL-SHAPED ARTHROCONIDIA
✅ rope-like strands
✅ racquet forms
✅Coccidiodomycosis/Cocci/ Desert Fever/Valley fever/ Desert Rheumatism/ “The Bumps”/ ✅San Joaquin Valley Fever/ Posadas Werneckii
causative agent
✅ “LOLLIPOP conidia”
✅ BROAD-BASED BUDDING thick walled yeast cells
Blastomycosis/ Gilcrhrist’s Disease/Chicago Disease/ North American Blastomycosis
causative agent?
“MARINER’S WHELL
PARACOCCIDIOIDOMYCOSIS/SOUTH AMERICAN BLASTMYCOSIS/ “PARA” or “PARACOCCI”/ ALMEIDA”S DISEASE/ LUTZ SPLENDORE ALMEIDA’S DISEASE
NOTE !!!
- Opportunistic Fungi
✅ Candida species( causing aspergillosis)
✅ Cryptococcus( causing cryptococcosis)
✅ Zygomycetes (causing zygomycosis)
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What is the colony characteristic of blastomycosis?
PRICKY STATE”
What is the mode of transmission of Histoplasmosis?
Inhalation from bird droppings
What is the method that is considered by most laboratories to be the most conclusive method for making a definitive identification of dimorphic fungi?
Exoantigen test
What is the microscopic features from the culture of the etiologic agent of San Joaquin Valley Fever?
Chains of alternate Barrel-shaped arthroconidia
What is the diagnostic characteristic of Almeida’s disease?
Multiple budding cells resembling “MARINER’S WHEEL”’
What is the serologic test used for the diagnosis of systemic mycoses?
Exoantigen test
What are the other names of Blastomycosis?
Gilchrist’s disease, or Chicago Disease or North American Blastomycosis
An etiologic of coccidiodomycosis which was considered to be a major biohazard
Coccidiodes immitis
What are the 2 etiologic agents of Darling’s disease?
- Histoplasma capsulatum,
- Emmonsiella capsulatum
What is the colony characteristic of blastomycosis?
“PRICKLY STATE”
most often seen in clinical laboratory
Aspergillus fumigatus
causes oncomycosis
Aspergilus flavus
major cause of otomycosis
- In tissue or sputum ( 10-20% KOH): HYALINE, DICHOTOMOUSLY BRANCHED, SEPTATE
HYPHAE
https://quizlet.com/141000866/micro-rotation-week-6-mycology-flash-cards/
What fungus causes Tinea Nigra, which is sometimes confused with malignant melanoma?
Hortaea werneckii
Aerial hyphae: macroconidia resembling “beaver tails”
Epidermophyton floccosum
Describe the macroscopic and microscopic presentation of Tri- chophyton rubrum.
Macroscopic:
Forward is white (yellow to red as it ages), Reverse is deep burgundy red on PDA.
