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Skin MS: Week 2 > Fungal Skin Infections > Flashcards

Fungal Skin Infections Flashcards

1
Q

What kinds of food to eat with Griseofulvin?

A

High fat

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2
Q

Side effects of Griseofulvin?

A

Teratogenic, disulfiram rexn with alcohol, monitor blood/liver enzymes

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3
Q

Spectrum for griseofulvin

A

Dermatophytes

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4
Q

Why not nystatin for dermatophytes?

A

Intrinsically resistant

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5
Q

What helps increase absorption for azoles?

A

Cola/acid

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6
Q

What drugs can you take for dermatophytes?

A

Griseofulvin Itraconazoles Terbinafine Oral for hair/nail

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7
Q

What fungus is behind seborrheic dermatitis

A

Malessezia - inflammatory rexn

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8
Q

DX of Malessezia

A

Yellow-green Wood’s Spaghetti and meatbals

Cultures require olive oil

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9
Q

Fungus behind tinea versicolor

A

Malessezia furfur

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10
Q

Dermatophyte examples

A

Trychophyton, Microsporum, Epidermophyton

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11
Q

What do dermatophytes need to live?

A

KEratin Grow best at 25C - invasion rare

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12
Q

Epidermophyton Floccosum causes —>

A

Tinea cruris, pedis - less common

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13
Q

Epidermophyton floccosum spread and appearance

A

Anthropophilic, dumbbel

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14
Q

Microsporum DX

A

KoH - Spindle Wood’s green’blue

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15
Q

Microsporum Types

A

Canis - zoophilic Fulvin - geophilic (soil)

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16
Q

Microsporum causes ______

A

Hair (ecto) + skin

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17
Q

Trichophyton rubrum DX, causes, spread

A

Cigar macro + micro, no fluorescence serpentine lesions with central clearing anthropophilic tinea pedis (most common cause)

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18
Q

Trichophyton tonsurans - causes

A

Tinea capitis in kids - endothrix

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19
Q

Candida albicans

A

opportunistic diaper dermatitis, chelitis, paronychia, thrush –> systemic

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20
Q

Sporothrix schenckii

A

Dimorphic Rose Gardener’s Disease (puncture) –> spread via lymph Nodular lesions Biopsy a leasion Itraconazole

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21
Q

Fungus characteristics

A

eukaryotic, heterotroph

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22
Q

Single cell, spheres reproduce by budding

A

Yeast

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23
Q

Multicellular, thread like filaments called _______

_______

A

Hyphae

(Molds)

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24
Q

Dimorphic fungi

A

Yeast-heat, in body

Mold-cold, environment

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25
Q

_______ is a mass of filaments and produce spores called _______

A

Mycelium is a mass of filaments and produce spores called conidia

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26
Q

Fungal plasama membrane contains ________

A

ergosterol

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27
Q

Antifungals used to treat skin infections

A
  1. Polyene- Nystatin
  2. Azoles- Fluconazole, Itraconazole, Voriconazole,
  3. Butenafine, Terbinafine, Tolnaftate
  4. Griseofulvin
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28
Q

Nystatin mechanism, spectrum, adverse effect, resistance

A

Binds ergosterol, creating holes in membrane allowing leakage of electrolytes. Fungicidal

Broad spectrum - yeast and molds. Candida (skin, mouth, vagina)

***Dermatophytes are intrinsically resistant.

AE: PO - Nephrotoxic

Resistance: Rare, decrease ergosterol in membrane

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29
Q

Azoles names, mechanism, spectrum, adverse effect, resistance

A

Fluconazole (Diflucan), Itraconazole (Sporanox)- oral
Clotrimazole, Miconazole, Ketoconazole

Mechanism: binds fungal P-450 enzyme (Erg11) blocking the production of ergosterol, Fungistatic

Spectrum: Most widely used antifungal and spectrum varies by agent

Distribution: Orally available; cola/acid helps absorption of itraconazole

Toxicity: Drug-Drug interactions, hepatotoxicity, neurotoxicity, alters hormone synthesis- avoid during pregnancy.

Resistance: Altered cytochrome P-450, Upregulation of efflux transporters

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30
Q

___________ intrinsically resistant to nystatin

A

dermatophytes

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31
Q

______ helps absorption of intraconazole

A

cola/acid

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32
Q

Bensylamine and allyamine names, mechanism, spectrum, toxicity, resistance

A

Benzylamine- Butenafine (Lotrimin)
Allyamine- Terbinafine (Lamisil)
Tolnaftate (Tinactin)

Mechanism: Inhibits squalene epoxidase lead to toxic accumulation of squalene, fungicidal

Spectrum: Broad, Dermatophytes, Candida, Sporothrix

Toxicity: Topical, severe hepatitis if given orally and drug-drug interactions avoid in individuals with liver disease

Resistance: Rare

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33
Q

Binds ergosterol, creating holes in membrane allowing leakage of electrolytes. Fungicidal

A

Polyene (nystatin, amphotericin)

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34
Q

binds fungal P-450 enzyme (Erg11) blocking the production of ergosterol, Fungistatic

A

Azoles: Fluconazole (Diflucan), Itraconazole (Sporanox)- oral
Clotrimazole, Miconazole, Ketoconazole

35
Q

Inhibits squalene epoxidase lead to toxic accumulation of squalene, fungicidal

A

Benzylamine- Butenafine (Lotrimin)
Allyamine- Terbinafine (Lamisil)
Tolnaftate (Tinactin)

36
Q

Summary of ergosterol inhibitors

A

Allyamine/benzylamine block squalene epozidase –> accumulation of sqalene = fungicidal

Azoles block lower down at P450 to block production of ergosterol = fungistatic

Polyene BINDS ergosterol –> holes to leak of electrolytes = fungicidal

37
Q

Griseofulvin

A

Mechanism: Binds microtubules inhibits spindle leading to multinucleate cells, fungistatic so treat for 4-6 weeks

Spectrum: Dermatophytes

Distribution: Lipids increase oral absorption

concentrates in dead keratinized layer of the skin

Toxicity: Teratogenic, Disulfiram reaction,

Monitor hematology, renal, and hepatic function

Resistance: change to beta-tubulin, compliance can be a challenge

38
Q

Binds microtubules inhibits spindle leading to multinucleate cells, fungistatic so treat for 4-6 weeks

A

Griseofulvin

39
Q

_____ increase oral absorption of Griseofulvin

40
Q

Griseofulvin concentrates in _________

A

dead keratinized layer of skin (why its so great for dermatophytes)

41
Q

Other txs for antifungal

A
  • Selenium sulfide
  • Tea-tree oil, Oregano, Garlic, Lavendar
  • Yogurt

Keratolytic agents

Whitfield’s ointment = salicyclic + benzoic acid

Carmol cream- 20-40% Urea

Avoid steroid creams!

42
Q

Pathogenesis pathways of fungi

A
  1. Hypersensitivity reaction to the molds or spores
  2. Mycotoxicoses- poisoning from toxins made by a fungus
  3. Mycosis- fungus grows on or in the individual
43
Q

Cutaneous fungal infections

A

Malassezia (tinea versicolor)

Dermatophytes- Microsporum, Epidermophyton, Trichophyton

44
Q

Subcutaneous fungal infections

A

infection enter through skin followed by subcutaneous and/or lymphatic spread

Sporothrix

45
Q

Opportunistic mycoses

A

Candida albicans

part of normal flora

Overgrowth in patients with immune deficiencies

46
Q

Dx labs fungal skin infections

A

Confirm by collecting skin, nail, or hair with scraping
and look at morphology
10% KOH (dissolves human tissue)
View under microscope 40X

Wood’s lamp (UV-A light) to detect fluorescent organisms

Can culture in Sabouraud media

Skin biopsy with Periodic Acid- Schiff stain (carbohydrates

47
Q

Tinea versicolor (pityriasis versicolor) caused by

A

Malassezia furfur

yeast convert to mold, part of normal flora requires lipids found predominantly in areas rich in sebaceous glands

48
Q

Tx Malessezia furfur

A

Topical therapy: Selenium sulfide shampoo

Reoccurrence common

49
Q

Cradle cap, seborrheic dermatitis

A

inflammatory response to Malassezia

50
Q

Seborrheic dermatitis, cradle cap tx

A

Topical therapy: Selenium sulfide shampoo

Reoccurrence common

51
Q

Dermatophytes (3)

A

Trichophyton

Microsporum

Epidermophyton

52
Q

Dermatophytes pathogenesis

A

Monomorphic molds secrete proteases and keratinases

Fungal antigens cause inflammation (Kerion).

Grow best at 25°C unable to survive at 37°C so rarely see further invasion

53
Q

Dermatophytes dx

A

KOH test, grow on Sabouraud’s agar

Some of them - Wood’s Lamp

54
Q

Treatment dermatophytoses

A

Topical griseofulvin, terbinafine or itraconazole 1 month

Oral for nail, hair infections but need to monitor for hepatotoxicity

Often reoccur

55
Q

3 modes of dermatophyte transmission

A
  1. Anthropophilic- person to person or fomite, found solely on humans, less conidiation
  2. Zoophilic- animal to human
  3. Geophilic- soil
56
Q

most common cause of tinea pedis

A

Trichophyton rubrum infections (serpentine lesion with central clearing)

57
Q

Trichophyton rubrum spread

A

anthropophilic- transfer at swim pools

58
Q

Most common cause in US of tinea capitis in children (endothrix)

A

Trichophyton tonsurans

59
Q

Trichophyton rubrum microscopy

A

macro (cigar shape) and microconidia

60
Q
A

Trichophyton rubrum (macro = cigar shaped, microconidia)

61
Q

Microsporum likes to infect —

A

hair (ectothrix) and skin

62
Q

Spreads of m. canis and m. fulvum

A

canis - zoophilic (cats, dogs)

fulvum - geophilic (soil)

63
Q

Microsporum labs

A

spindle shaped macroconidia

Wood’s light blue-green

64
Q

Sxs tinea versicolor

A

hypo/hyperpigmentation on back

65
Q

Spindle shape macroconidia

Wood’s light blue-green

66
Q

Cause of tinea cruris and tinea pedis (less commonly)

A

epidermophyton floccosum

67
Q

epidermophyton floccosum spread

A

anthropophilic

68
Q

epidermophytom floccosum microscopy

A

dumbbell shaped macroconidia

69
Q

cause of “rose gardener’s disease”

A

puncture with infected plant or cat bite/ scratch

dimorphic, Sporothrix schenckii

70
Q

Sporothrix schenckii pathogenesis

A

Fungi spread along lymphatic channels forming nodular lesions.

Extracutaneous in immunocompromised patients.

71
Q

Dx Sporothrix schenckii

A

Few organisms for scraping, biopsy lymph node and culture in Sabouraud agar containing antibiotics

72
Q

Sporothrix schenckii tx

A

Oral itraconazole for 3-6 months and apply heat- pregnant patient

73
Q

Sporothrix schenckii microscopy

A

Rosette formation (ROSE gardener’s ds)

74
Q

Occurs in immunocomprimised (normal part of flora)

A

Candidiasis- Candida albicans
commensal,
taking an antibiotic increases risk of
overgrowth, more common in individuals
with T-cell dysfuntion or diabetes

75
Q

candida infections

A

Superficial: Diaper dermatitis (diaper rash in folds and around anus), Angular chelitis (corners of the mouth), paronychia (toenail or edge of nails) thrush (oropharyngeal)

Vaginal and systemic infections

76
Q

dx candidiasis

A

Based on clinical appearance but can do skin scraping

77
Q

Candidiasis tx

A

Keep skin dry, Clotrimazole or other –azole cream (also Nystatin?)

78
Q

Trichophyton tonsurans _______ fluoresce

79
Q

Spindle shaped, blue-greed wood’s

A

Microsporum canis

80
Q

endo vs ectothrix

A

endo - inside - T. tonsurans - more chronic

ecto - m. canis

Can lead to alopecia

81
Q

which drugs PO?

A

fluconazole, itraconazole

82
Q

What types fungi associated w/ onychomycosis??

A

T. rubrum (spread of foot –> nail) - most common cause of tinea pedis

Trichophyton metagrophytes (more white, common in kids)

Epidermophyton floccosum (less common)

Skin MS: Week 2 (12 decks)

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