Chapter 21: The Fungi Flashcards Preview

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Flashcards in Chapter 21: The Fungi Deck (48):
1

Yeast

Unicellular growth form of fungi
Spherical to ellipsoidal
Budding
Pseudohyphae: do not complete bud, long chain

2

Hyphae

Threadlike, branching, cylindrical, tubules composed of fungal cells attached end to end
Grow by extending in length

3

Molds

Also called Mycelia
Multicellular colonies composed of clumps of intertwined branching hyphae
Grow by longitudinal extension and produce spores

4

Spores

Reproducing bodies of molds
Rarely seen in skin scarpings

5

Dimorphic fungi

Fungi that can grow as either a yeast or mold
depends on environmental conditions and temperature
Yeast at body temp

6

Saprophytes

Fungi that live in the utilize organic matter (soil, rotten vegetation) as an energy source

7

cell membrane of fungi?

Bilayered, innermost layer around fungal cytoplasm
It contains sterols
Ergosterol is essential

8

Cell wall of fungi

Surrounds cell membrane
Mostly carbohydrate with some protein
Potent antigens to human immune system

9

Capsule of fungi

Polysaccharide coating that surrounds the cell wall
Antiphagocytic virulence factor
Indian ink stain makes visible

10

What are the Extremely superficial fungus infections?

Pityriasis versicolor and Tinea nigra

11

Pityriasis versicolor

Chronic superficial fungal infection which leads to hypopigmented or hyperpigmented patches on the skin
Will not tan with sun
Caused by Malessezia furfur

12

Tinea nigra

Caused by Exophiala werneckii
Superficial fungal infection
Dark brown to black painless patches on soles of hands and feet

13

Dermatophytoses

Cutaneous fungal infections
Live in dead, horny layer of skin, hair and nails
Secrete keratinase: digest keratin
Manifest as scaling of the skin, loss of hair, and crumbling of the nails

14

What are the common dermatophytes?

Microsporum, Trichophyton, and Epidermophyton

15

Tinea corporis

Ring-worm
Invades horny layer, fungi spread forming a ring with red, raised border

16

Tinea cruris

Jock itch
Itchy red patches on groin and scrotum

17

what are the Cutaneous fungal infection of the skin, hair and nails ?

Tinea corporis
Tinea cruris
Tinea pedis
Tinea capitis
Tinea unguium

18

Tinea pedis

Athlete's foot
Begins between toes
Causes cracking and peeling of skin
Warmth and moisture needed for growth

19

Tinea capitis

Primarily in children
Grows in hair and scalp
Scaly red lesions with loss of hair
Expanding ring

20

Tinea unguium

Onychomycosis
Nails thickened, discolored, and brittle

21

Candida albicans

Cutaneous fungal infection
Causes Candida:
Mouth - oral thrush
groin - diaper rash
vagina - Candida vaginitis
Cause opportunistic systemic infections

22

Sporothrix schenckii

Dimorphic fungi commonly found in soil and on plants Branching Hyphae
Causes: Sporotrichosis - subcutaneous nodule appears, becomes necrotic and ulcerates
Ulcer heals but new nodules pop up nearby and along lymphatic tracts
Gardeners beware!!

23

Phialophora and Cladosporium

Causes Chromoblastomycosis: cauliflower warts on skin
Subcutaneous infection caused by the copper-colored soil saprophytes
Puncture wound-small violet wartlike lesion-->
over months to years, more wartlike lesions arise
Looks like cauliflower

24

What are the three fungi that can cause systemic disease in humans? Describe the common characteristics

Histoplasma capsulatum
Blastomyces dermatidis
Coccidioides immitis

All are dimorphic fungi
grow as mycelial forms with spores @ 25C
Grow as yeast form @ 37C
In soil the grow as mycelia and release spores into the air -->inhalation

25

Histoplasma and Blastomyces are found where ?

endemic to the vast areas that drain into the Mississippi river

HITS and BLASTS holes in Mississippi river

26

Coccidioides are found where?

endemic to southwestern U.S and northern Mexico

27

What is the second most common opportunistic infection in AIDS pts who are in Arizona?

Coccidioides

28

Histoplasma capsulatum, Blastomyces dermatidis, Coccidioides immitis have what 3 clinical presentations?

Asymptomatic
Pneumonia: mild, can have fever, cough, chest X-ray infiltrates, granulomas with calcifications
Disseminated: rarely causes meningitis, bone lytic granulomas, skin granulomas, mostly immunocompromised

29

How are Histoplasma capsulatum, Blastomyces dermatidis, Coccidioides immitis not similar to Tuberculosis?

No person-person transmission
Fungi with spores, NOT acid-fast bacteria

30

Histoplasma capsulatum

nonencapsulated
Bird and bat droppings
Outbreaks of pneumonia occur when cleaning chicken coops or spelunking

31

Blastomyces dermatitidis

Soil and rotten wood
Rarest systemic fungal infection
Rarely asymptomatic or mild - most chronic disseminated disease with weight loss, night sweats, lung involvement and skin ulcers

32

Coccidioides immitis:

commonly causes a mild pneumonia in normal persons in the southwestern US
Common opportunistic infection in AIDS pts from that area

33

Cryptococcus neoformans

Widespread
more common Cryptococcus to infect humans
Polysaccharide encapsulated yeast
Inhaled into lungs
Usually asymptomatic
Pigeon droppings

34

What is the major manifestation of cryptococcus neoformans?

Meningoencephalitis
Most occur in immunocormpromised
Subacute to chronic meningitis with headache, nausea, confusion, staggering gait, CN deficits
Cerebral edema fatal if left untreated
Lumbar puncture

35

What does Candida albicans cause in normal hosts?

Oral thrush: creamy white exudate with reddish base cover mucous membranes of the mouth
Vaginitis: Vaginal itching and discharge, cottage cheese on wall
Diaper rash: diapers or skin folds on adults become read and macerated

36

What does Candida albicans cause in immunocompromised pts

Esophagitis: Burning substernal pain worse with swallow
Disseminated: Retina - multiple white fluffy patches, in bloodstream

37

Aspergillus fumigatus causes what three major types of diseases in humans?

Allergic Bronchopulmonary Aspergillosis
Aspergilloma
Invasive aspergillosis

38

Allergic Bronchopulmonary Aspergillosis

Spores of aspergillus inhaled
Develop asthma-type reaction
Type 1 hypersensitivity reaction (IgE-mediated)
Bronchospasms
Also a type 4 reaction with cell-mediated inflammation and lung infiltrates

39

Aspergilloma

Person with lung cavitation from tuberculosis or malignancies can grow an aspergillus fungal ball in the cavity

40

Aspergillus and other fungi produce toxins that cause liver damage. what are they called/

mycotoxins
Toxin produced by aspergillus is called aflatoxin (peanuts, grains, and rice)

41

Mucormycosis

Opportunistic disease caused by mucorales
Rhizopus, Rhizomucor, and Mucor

42

Mucorales molds are found where? Who is at risk?

Found everywhere
At risk: those that develop profound acidosis, such as diabetics, the immunocompromised, burn pts, persons taking iron chelator deferoxamine

43

Rhinocerebral and ____ involvement is most common

pulmonary

44

Actinomycetes

bacteria acting like fungi
Procaryotic organisms
Frequently grow in the form of mycelia
Water and soil saprophytes
Acinomyces Israelli
Nocardia asteroides

45

Actinomyces Israelli

Gram positive, beaded, filamentous anaerobic organisms, normal flora
Causes eroding abscesses
Pus is yellow granules called sulfure granules

46

What are the abscesses formed due to Actinomyces?

Cervicofacial actinomycosis
Abdominal actinomycosis
Thoracic actinomycosi
Depends on what area of the body the abscess erodes

47

Nocardia asteroides

Weakly gram-positive
Partially acid-fast beaded branching thin filaments
Not normal flora
Infections misdiagnosed as tuberculosis bc acid-fast staining and same disease process
Inhaled and produces lung abscesses and cavitations
Brain and other organs can have abscesses when erosion occurs

48

Who is at particular risk for infection of Nocardia ?

immunocompromised pts