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🥇Medical Mycology (ALL) Flashcards

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USMLE® Step 1 flashcards
1
Q

The term “mycology” is derived from Greek word “mykes” meaning?

A

mushroom

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2
Q

2 Basic Fundamental Structures of fungi

A

Hyphae
Spores

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2
Q

Fungi are achlorophyllous meaning what?

A

can not manufacture its own food

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3
Q

T/F

Fungi grow I the presence of acid and large amount of sugar (SDA- with pH of 5.6) which inhibits bacteria

A

T

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4
Q

2 Morphologic Forms of Fungi

A

Yeast
Mold

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5
Q

✅ 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

A

Yeast

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6
Q

Produces multicellular filamentous colonies: Fluffy, cottony, wooly or powdery

A

Mold

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7
Q

The basic structural unit of mold which can be divided in to: Septate, Aseptate, Mycelium

A

Hyphae

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8
Q

Side note:

Which can be divided into 2: a. Vegetative or Substrate b. Aerial or Reproductive mycelium

A

🩵

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9
Q

(when hyphae overlaps one from the other), hyphae forms a mass of intertwining strands

A

Mycelium

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10
Q

3 COMMON FORMS OF HYPHAE

A

✅ Antler Hyphae/Favic Chandelier

✅ Racquet hyphae

✅ Spiral hyphae

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11
Q
  • The capability of an organism to grow in more than one form under different environment
A

✅ Dimorphism

(Monomorphic- The opposite)

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12
Q

T/F

Sporothrix schenkii exhibits Dimorphism characteristics

A

T

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13
Q

derived from fusion of identical cells from the same hyphae

A

Zygospores/Zygomycetes

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14
Q

Spores enclosed in a specific sac called ascus (asci)

A

Ascospores/Ascomycetes

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15
Q

enclosed in a club-shaped structures called basidia or basidium

A

Basidiospores/Basidiomycetes

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16
Q

derived from fusion of non-identical cells from the same hyphae

A

Oospores

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17
Q

Side note:

Asexual (anamorph) = imperfect fungus (Fungus imperfecti)

A

🩵

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18
Q

Buds formed by budding process, sprouting from the surface of the parent cell

A

Blastospores

Ex. Candida albicans
Cryptococcus neoformans

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19
Q

derived from the cells of the thallus or body of the fungi

A

Thalospores

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20
Q

Arise by fragmentation of the ends of hyphae at the point of septation; square barrel-shaped thick walled cells

A

Arthrospores/Arthroconidia

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21
Q

When hyphal cells separate from one another to form flat ended spores

A

✅ Oidia

Example:Geotrichum candidum

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22
Q

Enlarged, round unicellular thick-walled structures that are formed during unfavorable conditions; formed by the enlargement of a hyphal cell

A

Chlamydospores/Chlamydoconidia

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23
Q

3 types of Chlamydospores

A

TIS

✅ Terminal
✅ Intercallary
✅ Sessile

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24
Q

Born internally within a sac called “SPORANGIUM”, which develops at the tip of the sporangiophore

A

Sporangiospores

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25
Q

Asexual spores produces singly or in groups (en-grape) by specialized vegetative strands/branch called Conidiphore (borne externally not with in)

A

Conidia

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26
Q

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

A

🐈

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27
Q

2 Sized of Conidia

A

✅Microconidia/Microaleuriospores

✅Macroconidia/Macroaleriospores

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28
Q

(3) DIAGNOSTIC METHODS USED FOR FUNGAL IDENTIFICATION

A

✅ Direct Examination
✅ Fluorescence
✅ STAINING

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29
Q

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)

A

🩵

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30
Q

3 Direct Examination methods

A

✅ KOH (10-20%)
✅ India Ink
✅ Lactophenol Cotton Blue (stain used is AMAN Medium - Observe for spores, yeast cells and hyphae)

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31
Q

Best staining for visualizing fungi in skin scraping or tissue If dematiaceous, appears as dark brown/black

A

PAS staining

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32
Q

Gridley, Gomori-Methenamine Silver
Excellent for STAINING yeast cells of H. capsulatum in TISSUE

A

Wright’s Stain or Giemsa

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33
Q

Best stain for B. dermatitidis

A

Papanicolau method

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34
Q

Stain ideal for T. versicolor

A

Acridine Orange

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35
Q

Useful in the differentiation of Nocardia from Actinomyces Hyphae of Nocardia steroids and Nocardia brasilliensis are partially acid fast

A

Acid Fast Stain (Kinyoun)

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36
Q

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

A

🐈

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37
Q

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

A

🐈

38
Q

Fungi has a rigid cell wall made of?

A

chitin

…..which may be layered with mannans, glucans and other polysaccharides in association with polypeptides.

39
Q

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.

A

🐈

40
Q

Fungal membranes possess______ in contrast to cholesterol found in mammalian cells.

A

ergosterol

41
Q

Type of mycoses that is - Limited or confined to the outermost layer of the skin, hair and nails
- Does not invade living tissue

A

SUPERFICIAL MYCOSES

✔Profuse sweating
✔ Poor hygiene
✔ Poor immunityPoor hygiene
✔ Poor immunity

42
Q

Spaghetti and meatballs

Symptoms: Hypopigmented macules

A

Pityriasis versicolor

-Malassezia furfur

43
Q

Black, 2-celled oval yeasts in skin scrapings

-Commonly found on the palms

-Symptoms: Black macules

A

Tinea nigra

-Exophilia werneckii

44
Q

Black nodules on hair shaft composed of spore sacs and spores

-black nodule on hair shaft

what is the disease

A

Black piedra

-Piedraia hortae

45
Q

White nodules on hair shaft

-creme coloured nodukes on hair shaft

A

White piedra

-Trichosporum beigelii

46
Q
  • 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

A

Keratomycosis (Keratitis/ Keratomycosis/ Keratitis)

47
Q

Mode of action: inhibits CYP P450 14 a-demethylase enzyme involved in conversion of lanosterol to ergosterol

A

Azoles: Ketaconazole, fluconazole, Voriconazole

48
Q

binds to ergosterol in fungal cell membrane & cause the membrane to
become leaky.)

A

Polyenes: Amphotericin B, Natamycin

49
Q

causes faulty RNA synthesis & non competitive inhibitor of Thymidylate
synthesis

A

Pyrimidines: Flusytosine

50
Q

Ergosterol Biosynthesis inhibitor

A

Allylamines: Terbinafine

51
Q

✅ Clinical picture: Chronic fungal infection of the outer ear canal -

✅ Organism responsible: Candida albicans, Candida tropicalis
Aspergillus fumigatus, Aspergillus niger

A

Otomycosis/ Mycotic Otitis Externa

52
Q

Etiologic agent; Piedraia hortae

  • Occurs on scalp
  • Microscopic appearance: 10-290% KOH- hard and black nodules resembling nits of lice
A

BLACK PIEDRA

53
Q

Etiologic agent: Tricosporon beigelii

  • Microscopic appearance: white nodules lager and softer
  • Septate not dematiaceous
A

WHITE PIEDRA

54
Q

✅ 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

A

Tinea nigra/ Keratomycosis nigricans palmaris/ Tinea nigra palmaris/Pytyriasis nigra/Microsporis nigra

55
Q

🤰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”

🍝🍝🍝🏀🏀

A

Pityriasis versicolor

56
Q

is a disease of the skin and its appendages caused by fungi.

It comprises dermatophytosis, candidiasis, and pityriasis versicolor

A

Superficial mycosis

57
Q

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.

A

🐈

58
Q

Disease associated:
✔ Ringworm
✔ Jock itch
✔ Athlete’s foot
✔ Dermatomycoses

  • ✔ Invades the keratinized areas of the body as skin, hair and nails
A

CUTANEOUS MYCOSES/ DERMATOMYCOSES

59
Q

Breakdown and use____ as a source of nitrogen but are usually incapable of penetrating the subcutaneous
tissues

A

keratin

60
Q

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

A

🩵

61
Q

=affects the hair and skin

A

Microsporum

62
Q

=affects the hair,skin and nails

A

Trichophyton

63
Q

=affects the skin and nails

A

Epidermophyton

64
Q

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
A

🐈

65
Q

Tinea unguium affects the whaT???!

A

Nail (Onchomycosis)

66
Q

3 GENERA CAUSING RINGWORM

A

Microscporum - hair/skin
Trichophyton - hair/skin/nail
Epidermophyton - nail/skin

67
Q
  • 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
A

Sporothricossis/Rose Gardener’s Disease

68
Q

tumor-like lesions characterized as “ cauliflower-like”

A

Chromomycosis/Chromoblastomycosis/Verrucous dermatitidis

69
Q
  • 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
A

Mycetuma/Madura foot/Maduramycosis

70
Q
  • Initial lesions are small, hard and subcutaneous nodules appearing on the extremities, face or ear
  • Lymhp nodes are not involved
  • Etiologic agent: Loboa loboi
A

Lobomycosis

71
Q

✅ Tumor-like polyp usually on the nose

✅ Etiologic agent: Rhinosporidium seeberi

✅ Acquired from stagnant water

A

Rhinosporidiosis

72
Q

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)

A

Histoplasma capsulatum

73
Q

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

A

✅Coccidiodomycosis/Cocci/ Desert Fever/Valley fever/ Desert Rheumatism/ “The Bumps”/ ✅San Joaquin Valley Fever/ Posadas Werneckii

74
Q

causative agent

✅ “LOLLIPOP conidia”
✅ BROAD-BASED BUDDING thick walled yeast cells

A

Blastomycosis/ Gilcrhrist’s Disease/Chicago Disease/ North American Blastomycosis

75
Q

causative agent?

“MARINER’S WHELL

A

PARACOCCIDIOIDOMYCOSIS/SOUTH AMERICAN BLASTMYCOSIS/ “PARA” or “PARACOCCI”/ ALMEIDA”S DISEASE/ LUTZ SPLENDORE ALMEIDA’S DISEASE

76
Q

NOTE !!!

  • Opportunistic Fungi
    ✅ Candida species( causing aspergillosis)
    ✅ Cryptococcus( causing cryptococcosis)
    ✅ Zygomycetes (causing zygomycosis)
A

🐈

77
Q

What is the colony characteristic of blastomycosis?

A

PRICKY STATE”

78
Q

What is the mode of transmission of Histoplasmosis?

A

Inhalation from bird droppings 


79
Q

What is the method that is considered by most laboratories to be the most conclusive method for making a definitive identification of dimorphic fungi?

A

Exoantigen test 


80
Q

What is the microscopic features from the culture of the etiologic agent of San Joaquin Valley Fever?

A

Chains of alternate Barrel-shaped arthroconidia

81
Q

What is the diagnostic characteristic of Almeida’s disease?

A

Multiple budding cells resembling “MARINER’S WHEEL”’

82
Q

What is the serologic test used for the diagnosis of systemic mycoses?

A

Exoantigen test 


83
Q

What are the other names of Blastomycosis?

A

Gilchrist’s disease, or Chicago Disease or North American Blastomycosis 


84
Q

An etiologic of coccidiodomycosis which was considered to be a major biohazard

A

Coccidiodes immitis

85
Q

What are the 2 etiologic agents of Darling’s disease?

A
  1. Histoplasma capsulatum,
  2. Emmonsiella capsulatum
86
Q

What is the colony characteristic of blastomycosis?

A

“PRICKLY STATE”

87
Q

most often seen in clinical laboratory

A

Aspergillus fumigatus

88
Q

causes oncomycosis

A

Aspergilus flavus

89
Q

major cause of otomycosis

  • In tissue or sputum ( 10-20% KOH): HYALINE, DICHOTOMOUSLY BRANCHED, SEPTATE
    HYPHAE
A

https://quizlet.com/141000866/micro-rotation-week-6-mycology-flash-cards/

90
Q

What fungus causes Tinea Nigra, which is sometimes confused with malignant melanoma?

A

Hortaea werneckii

91
Q

Aerial hyphae: macroconidia resembling “beaver tails”

A

Epidermophyton floccosum

92
Q

Describe the macroscopic and microscopic presentation of Tri- chophyton rubrum.

A

Macroscopic:
Forward is white (yellow to red as it ages), Reverse is deep burgundy red on PDA.

Medical Mycology (4 decks)

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