Fungal Skin Infections Flashcards
1
Q
What kinds of food to eat with Griseofulvin?
A
High fat
2
Q
Side effects of Griseofulvin?
A
Teratogenic, disulfiram rexn with alcohol, monitor blood/liver enzymes
3
Q
Spectrum for griseofulvin
A
Dermatophytes
4
Q
Why not nystatin for dermatophytes?
A
Intrinsically resistant
5
Q
What helps increase absorption for azoles?
A
Cola/acid
6
Q
What drugs can you take for dermatophytes?
A
Griseofulvin Itraconazoles Terbinafine Oral for hair/nail
7
Q
What fungus is behind seborrheic dermatitis
A
Malessezia - inflammatory rexn
8
Q
DX of Malessezia
A
Yellow-green Wood’s Spaghetti and meatbals
Cultures require olive oil
9
Q
Fungus behind tinea versicolor
A
Malessezia furfur
10
Q
Dermatophyte examples
A
Trychophyton, Microsporum, Epidermophyton
11
Q
What do dermatophytes need to live?
A
KEratin Grow best at 25C - invasion rare
12
Q
Epidermophyton Floccosum causes —>
A
Tinea cruris, pedis - less common
13
Q
Epidermophyton floccosum spread and appearance
A
Anthropophilic, dumbbel
14
Q
Microsporum DX
A
KoH - Spindle Wood’s green’blue
15
Q
Microsporum Types
A
Canis - zoophilic Fulvin - geophilic (soil)
16
Q
Microsporum causes ______
A
Hair (ecto) + skin
17
Q
Trichophyton rubrum DX, causes, spread
A
Cigar macro + micro, no fluorescence serpentine lesions with central clearing anthropophilic tinea pedis (most common cause)
18
Q
Trichophyton tonsurans - causes
A
Tinea capitis in kids - endothrix
19
Q
Candida albicans
A
opportunistic diaper dermatitis, chelitis, paronychia, thrush –> systemic
20
Q
Sporothrix schenckii
A
Dimorphic Rose Gardener’s Disease (puncture) –> spread via lymph Nodular lesions Biopsy a leasion Itraconazole
21
Q
Fungus characteristics
A
eukaryotic, heterotroph
22
Q
Single cell, spheres reproduce by budding
A
Yeast
23
Q
Multicellular, thread like filaments called _______
_______
A
Hyphae
(Molds)
24
Q
Dimorphic fungi
A
Yeast-heat, in body
Mold-cold, environment
25
\_\_\_\_\_\_\_ is a mass of filaments and produce spores called \_\_\_\_\_\_\_
Mycelium is a mass of filaments and produce spores called conidia
26
Fungal plasama membrane contains \_\_\_\_\_\_\_\_
ergosterol
27
Antifungals used to treat skin infections
1. Polyene- Nystatin
2. Azoles- Fluconazole, Itraconazole, Voriconazole,
3. Butenafine, Terbinafine, Tolnaftate
4. Griseofulvin
28
Nystatin mechanism, spectrum, adverse effect, resistance
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
29
Azoles names, mechanism, spectrum, adverse effect, resistance
Fluconazole (Diflucan), Itraconazole (Sporanox)- oral
Clotrimazole, Miconazole, Ketoconazole
## Footnote
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
30
\_\_\_\_\_\_\_\_\_\_\_ intrinsically resistant to nystatin
dermatophytes
31
\_\_\_\_\_\_ helps absorption of intraconazole
cola/acid
32
Bensylamine and allyamine names, mechanism, spectrum, toxicity, resistance
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
33
Binds ergosterol, creating holes in membrane allowing leakage of electrolytes. Fungicidal
Polyene (nystatin, amphotericin)
34
binds fungal P-450 enzyme (Erg11) blocking the production of ergosterol, Fungistatic
Azoles: Fluconazole (Diflucan), Itraconazole (Sporanox)- oral
Clotrimazole, Miconazole, Ketoconazole
35
Inhibits squalene epoxidase lead to toxic accumulation of squalene, fungicidal
Benzylamine- Butenafine (Lotrimin)
Allyamine- Terbinafine (Lamisil)
Tolnaftate (Tinactin)
36
Summary of ergosterol inhibitors
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
Griseofulvin
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
Binds microtubules inhibits spindle leading to multinucleate cells, fungistatic so treat for 4-6 weeks
Griseofulvin
39
\_\_\_\_\_ increase oral absorption of Griseofulvin
lipds
40
Griseofulvin concentrates in \_\_\_\_\_\_\_\_\_
dead keratinized layer of skin (why its so great for dermatophytes)
41
Other txs for antifungal
* 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
Pathogenesis pathways of fungi
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
Cutaneous fungal infections
Malassezia (tinea versicolor)
Dermatophytes- Microsporum, Epidermophyton, Trichophyton
44
Subcutaneous fungal infections
infection enter through skin followed by subcutaneous and/or lymphatic spread
Sporothrix
45
Opportunistic mycoses
Candida albicans
part of normal flora
Overgrowth in patients with immune deficiencies
46
Dx labs fungal skin infections
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
Tinea versicolor (pityriasis versicolor) caused by
Malassezia furfur
yeast convert to mold, part of normal flora requires lipids found predominantly in areas rich in sebaceous glands
48
Tx Malessezia furfur
Topical therapy: Selenium sulfide shampoo
Reoccurrence common
49
Cradle cap, seborrheic dermatitis
inflammatory response to Malassezia
50
Seborrheic dermatitis, cradle cap tx
Topical therapy: Selenium sulfide shampoo
Reoccurrence common
51
Dermatophytes (3)
Trichophyton
Microsporum
Epidermophyton
52
Dermatophytes pathogenesis
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
Dermatophytes dx
KOH test, grow on Sabouraud’s agar
Some of them - Wood's Lamp
54
Treatment dermatophytoses
Topical griseofulvin, terbinafine or itraconazole 1 month
Oral for nail, hair infections but need to monitor for hepatotoxicity
Often reoccur
55
3 modes of dermatophyte transmission
1. Anthropophilic- person to person or fomite, found solely on humans, less conidiation
2. Zoophilic- animal to human
3. Geophilic- soil
56
most common cause of tinea pedis
Trichophyton rubrum infections (serpentine lesion with central clearing)
57
Trichophyton rubrum spread
anthropophilic- transfer at swim pools
58
Most common cause in US of tinea capitis in children (endothrix)
Trichophyton tonsurans
59
Trichophyton rubrum microscopy
macro (cigar shape) and microconidia
60
Trichophyton rubrum (macro = cigar shaped, microconidia)
61
Microsporum likes to infect ---
hair (ectothrix) and skin
62
Spreads of m. canis and m. fulvum
canis - zoophilic (cats, dogs)
fulvum - geophilic (soil)
63
Microsporum labs
spindle shaped macroconidia
Wood's light blue-green
64
Sxs tinea versicolor
hypo/hyperpigmentation on back
65
Spindle shape macroconidia
Wood's light blue-green
66
Cause of tinea cruris and tinea pedis (less commonly)
epidermophyton floccosum
67
epidermophyton floccosum spread
anthropophilic
68
epidermophytom floccosum microscopy
dumbbell shaped macroconidia
69
cause of “rose gardener’s disease”
puncture with infected plant or cat bite/ scratch
dimorphic, Sporothrix schenckii
70
Sporothrix schenckii pathogenesis
Fungi spread along lymphatic channels forming nodular lesions.
Extracutaneous in immunocompromised patients.
71
Dx Sporothrix schenckii
Few organisms for scraping, biopsy lymph node and culture in Sabouraud agar containing antibiotics
72
Sporothrix schenckii tx
Oral itraconazole for 3-6 months and apply heat- pregnant patient
73
Sporothrix schenckii microscopy
Rosette formation (ROSE gardener's ds)
74
Occurs in immunocomprimised (normal part of flora)
Candidiasis- Candida albicans
commensal,
taking an antibiotic increases risk of
overgrowth, more common in individuals
with T-cell dysfuntion or diabetes
75
candida infections
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
dx candidiasis
Based on clinical appearance but can do skin scraping
77
Candidiasis tx
Keep skin dry, Clotrimazole or other –azole cream (also Nystatin?)
78
Trichophyton tonsurans _______ fluoresce
DOES NOT
79
Spindle shaped, blue-greed wood's
Microsporum canis
80
endo vs ectothrix
endo - inside - T. tonsurans - more chronic
ecto - m. canis
Can lead to alopecia
81
which drugs PO?
fluconazole, itraconazole
82
What types fungi associated w/ onychomycosis??
T. rubrum (spread of foot --\> nail) - most common cause of tinea pedis
Trichophyton metagrophytes (more white, common in kids)
Epidermophyton floccosum (less common)
83
