Chapter 160- Superficial Fungal infection Flashcards
Most common cause of dermatophytosis in the skin
Trichophyton rubrum
Most common cuase of tinea capitis in the United States
Trichophyton tonsurans
Asymptomatic superficial fungal infection of hair shaft
Piedra
Dermatophytes have ability to attach to, invade, and use ___ as source of nutrition
Keratin
Matching type
- Trichophyton
- Microsporum
- Epidermophyton
- Tinea nigra
- Black piedra
A. Skin B. Hair C. Nails D. A and B E. A and C F. All of the above
- F
- D
- E
- A
- B
- B
Asexual spore produced by by segmentation of hyphae
Arthroconidia
Melanin in the cell walls of its conidia, hyphae or both results in darkly colored fungus
Dematiaceous
Dermatophyte growth pattern with hyphae and air spaces within hair shaft
Favus
Long filamentous fungus cells forming a branching network called mycelium
Hyphae
Unlike the ___ geophilic and zoophilic infections, anthropophilic infections are often ___ in nature
Sporadic; epidemic
Most common geophilic dermatophyte cultured from humans
Microsporum gypseum
Most common cause of tinea capitis in Europe
Microsporum canis
Prevalence and severity of fungal infections increase with HIV infection.
True or False
False, only severity
Dermatophyte infections are ___ times more prevalent in males than females
5
Tinea means Latin for
Worm
First step of dermatophyte infection
Successful adherence of arthroconidia to keratin via adhesin to result in alteration of gene expression
Defective ___ cell-mediated immunity results in chronic or recurrent dermatophytosis
TH1
__ response does not appear to be protective for fungal infections
TH2
__ promote development of TH17 cells from naive T cells via STAT3 to induce transcription
IL1B, TGFB, IL6
Polymorphisms of ___ and ___ are associated with increased risk of invasive fungal diseases
TLR 1 and TLR4
Polymorphisms of ___ are associated with cutaneous candidiasis
TLR3
Contents of modified Sabouraud medium
4% peptone 1% glucose Agar Water \+ Chloramphenicol Cycloheximide Gentamicin
Modified Sabouraud medium inhibits growth of (6)
NonCandida albicans Cryptococcus Prototheca sp Phaeoanellomyces werneckii Scytalidum Ochroconis gallopava
Dermatophyte test medium makes use of indicator ___ which turns from ___ to ___ in presence of dermatophytes due to highly ___ environment
Phenol red
Yellow to bright red
Alkaline (ammonium)
Fungal HPX stains (2)
PAS (pink)
Grocott methenamine silver (black)
KOH examination may yield false negative in up to __% of cases
15
Most commonly used isolation medium for dermatophytes and serves as medium on which most morphologic descriptions are based
Sabouraud dextrose agar
Matching type
- Smooth walled microconidia; used for ID
- Smooth walled macroconidia; used for ID
- Rough walled macroconidia; used for ID
A. Trichophyton
B. Microsporum
C. Epidermophyton
A
C
B
Equivocal KOH results should be biopsied before treatment.
True or False
False, may be treated despite lack of confirmation
Most specific test for onychomycosis
Culture
Most sensitive test for onychomycosis
PAS examination of nail clippings
Used to differentiate T. Rubrum from T. Interdigitale
1. Urease test ; 2. Hair perforation test \+ : interdigitale - : rubrum 3. Potato dextrose agar None: interdigitale Cherry red: rubrum
Matching type
- T. Tonsurans
- T. Concentricum
- T. Violaceum
- T. Verrucosum
- T. Equinum
- T. Megninii
A. Histidine
B. Inositol
C. Nicotinic acid
D. Thiamine
1-3 D
4 B &;; D
5 C
6 A
Examples of endothrix (5)
T. Tonsurans T. Violaceum T. Soudanense T. Gourvilii T. Yaoundei
Examples of ectothrix with yellow green fluorescence (4)
M. Canis
M. Audouinii
M. Distortum
M. Ferrugineum
Reveal pteridine flourescence of hair infected with fungal pathogens
Wood lamp (365nm)
Dermatophytoses involving hair bearing skin and nails can be treated with topical antifungals.
True or False
False, oral antifungals
Matching type wirh pregnancy category
- Fluconazole
- Griseofulvin
- Itraconazole
- Terbinafine
A A B B C C D D E X
D
E
C
B
Matching type
- Amorolfine
- Butenafine
- Ciclopirox
- Clotrimazole
- Econazole
- Zinc pyrithione
A A B B C C D D E X
- C B B C C
Matching type
- Efinaconazole
- Gentian violet
- Ketoconazole
- Miconazole
- Povidone iodine
- Selenium sulfide
A A B B C C D D E X
C - C - C C
Most common genera isolated in the United Stated
Trichophyton
T. Rubrum
T. Interdigitale
Microsporum species that are anthropophilic (2)
M. Audouinii
M. Ferrugineum
Matching type
- T. Simii
- M. Canis
- T. Interdigitale
- T. Verrucosum
- T. Erinacei
A. Rodents B. Hedgehogs C. Primates D. Cattle E. Cats, dogs, horses
C E A D B
In Africa, the most common cause of tinea capitis are the ff (3)
M. Audouinii
T. Soudanense
T. Violaceum
Dermatophyte, Greek word for
Skin plant
Acute inflammatory dermatitis at sites distant from primary inflammatory fungal infection
Dermatophytid or id reaction
Pathogenesis of superficial fungal infection involves 3 steps:
Adherence
Invasion
Host reaction
Components of fungal cell wall that inhibits keratinocyte proliferation and cell mediated immunity (3)
B glucan
Galactomannan
Chitin
TLRs located on cell surface
1,2,4,5,6
TLRs in the endosomes
3,9
Macrophage ingest but is unable to digest T. Rubrum conidia due to increase (2) but no increased (2)
TNFA, IL10
IL12, NO
Critical for inducing TH17 responses
Dectin 2
TH17 secretion of (3) activates epithelial cells, granulopoiesis, neutrophil recruitment, production of chemokines crucial for epithelial immuniry against fungi
IL17A
IL17F
IL22
Mutations associated with chronic mucocutaneous candidiasis and chronic dermatophyte infections (3)
Polymorphisms of C type lectin receptor Dectin 1
Mutations of CamARD9
Decreased IL17 production
KOH does not allow for speciation of fungal species.
True or False
True
Aids penetration of KOH into keratin (2)
DMSO
Low intensity flame
Used for speciation of superficial fungi based on macro-/microscopic and metabolic characteristics
Culture
Development of colonies can take ___ days for E. Floccosum and ___ weeks for T. Verrucosum
5-7 days
4 weeks
For isolation of dermatophytes but does not allow for direct identification
Dermatophyte test medium
ID of isolated fungi is facilitated by subculture on specific media such as (2)
Potato dextrose agar
Borelli Lactritmel agar
Matching type (PDA pigment)
- T. Rubrum
- T. Interdigitale
- M. Audouinii
- M. Canis
A. Cherry red
B. Salmon pink
C. Yellow
D. None
A
D
B
C
Diff. M. Audouinii and M. Canis
Polished rice
+: M. Canis
-. M. Audouinii
Biopsy is useful in ff settings (3)
- Tx of recalcitrant or widespread eruption
- Majocchi granuloma
- Presence of hyphae in hair shafts on scalp
All oral antifungal agents can be used for onychomycosis except
Griseofulvin
First line Tx for onychomycosis
Terbinafine 250mg/ day for 6-12 weeks
First line for tinea capitis (Microsporum)
Griseofulvin 20-25mkday for 2-8 weeks (micro), if 2 years old and above
10-15mkday for 2-8 weeks (ultramicro), 2 years old and above
10mkday, 1 mo to 2 years
Topical antifungal for onychomycosis (4)
Ciclopirox 8% solution x 1 week
Amorolfine 250mg/5ml x 6-12 mos
Tioconazole 28% BID x 12 mos
Eficonazole 10% solution x 12 mos
All topical antifungals are pregnancy Category C except
Clotrimazole
Ciclopirox
Cat. B
All topica imidazoles are 1% except
Sertaconazole
Ketoconazole
Miconazole
Matching type Moa 1. Inhibits DNA, RNA, protein synthesis 2. Broad spectrum germicidal agent 3. Cytostatic effects on keratinocytes 4. Distorts hyphae and mycelial growth 5. Keratolytic
A. SeS 1-2.5% B. Zn pyrithione 1-2% C. Povidone iodine 7.5% D. Ciclopirox 8% E. Tolnaftate 1%
D C A E B
Only topical triazole available
Efinaconazole 10%
Can be used in children >/= 12 years old (4)
Terbinafine/ Butenafine
Ketoconazole/ Econazole
Used in children older than 2 years old
SeS
Tolnaftate
Ciclopirox 0.77% cream and suspension can be used in children more than ___
10 years old
Ciclopirox 0.77% gel and 0.1% shampoo can be used in children more than ___
16 years old
Ciclopirox 8% solution can be used in children more than ___
12 years old
