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Micro > skin 10: specific Tineas > Flashcards

skin 10: specific Tineas Flashcards

1
Q

Tinea pedis (Athlete’s foot) agents

A

“The big three”: T. mentagrophytes > T. rubrum > E. floccosum.

  • extent of the clinical features of symptomatic athlete’s foot are a result of the interaction of fungi and bacteria.
  • may involved nails
  • may affect hand: “2 foot, 1 hand syndrome”
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2
Q

Tinea pedis, common?
seasonality?
risk factors?

A

Most common dermatophytic infection infecting 30-70%
of the population.
peaks in summer and in the tropics (feet sweating the most, also old people who buy cheap plastic shoes),
Abrasion and high moisture. Occult nail infections serve as the reservoir for organisms causing tinea pedis. also in DM pts

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3
Q

Tinea pedis: 3 common manifestations

A

Intertriginous form.
Chronic, papulosquamous, hyperkeratotic form (moccasin type).
Vesiculobullous form.

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4
Q

T. pedis: Intertriginous form.

A

Peeling, maceration of skin between toes.
Foul odor. (due to G-orgs)
Very persistent; associated with hyperhidrosis. (sweaty)

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5
Q

T. pedis: Chronic, papulosquamous, hyperkeratotic form (moccasin type).

A

Pink skin covered by fine, silvery-white scales. (looks like wearing moccasin)
Very persistent; difficult to treat. T. rubrum (most DR)

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6
Q

T. pedis: Vesiculobullous form.

A

Vesicles, vesiculopustules, or bullae occur singly or in patches in an inflammatory pattern.
This form is most often responsible for “id” reaction.

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7
Q

?? is a potential complication of all three forms of tinea pedis.

A

Cellulitis, flatulence, aerosolizing orgs

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8
Q

T. pedis ddx

A

Contact dermatitis, eczema, and pustular psoriasis

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9
Q

Tinea manuum (Ringworm of the Hand) agents

A

Majority of infections caused by the big three: T. mentagrophytes > T. rubrum>E. floccosum, with T. rubrum dominating

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10
Q

Predisposing factors for T. manuum include ??

A 
concomitant infection (especially tinea pedis) and occupational compression of the interdigital spaces.
wearing gloves
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11
Q

Clinical manifestations of T. manuum reflect the manifestations seen with ??

A

T. pedis

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12
Q

Tinea cruris (Jock itch) agents

A

The big three T. mentagrophytes>T. rubrum>E. floccosum. with E. floccosum predominating

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13
Q

T. cruris age and gender??

A

Infection of the groin is more common in males and involves the perineum, scrotum, and perianal area and often the inner third of the buttock. Rare in childhood.

(spandex, tight clothes)

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14
Q

T. cruris clinical manifestations

A

Reddish-brown lesions are usually sharply demarcated with a raised, erythematous margin. Lesions are pruritic with bilateral but asymmetrical involvement. Central portion of lesion is rarely healed

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15
Q

T. cruris ddx

A
  1. Candidal intertrigo (Uniformly red, with no central clearing; satellite lesions)
  2. Erythrasma (Uniformly brown and scaly, with no active edge; fluoresces a brilliant coral red)
  3. Mechanical intertrigo (Sharp edge, no central clearing or scale)
  4. Psoriasis (Silvery scale and sharp margination; pitted nails; knee, elbow, and scalp lesions)
  5. Seborrheic dermatitis (Greasy scales; scalp (dandruff) and sternal involvement)
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16
Q 
Tinea unguium (Onychomycosis)
Ringworm of the nails agent
A

50% of all nail infections are caused by fungi. Trichophyton rubrum and
T. metagrophytes account for 90% of dermatophytic nail infections.
T. rubrum most difficult to tx

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17
Q

T. unguium infections often associated with ??

also occurs as a result of ??

A

other concomitant tinea infections.

trauma induced by manicures or pedicures. Nail infections serve as the reservoir for tinea pedis.
(factoid: pseudomonas grows in soapy water)

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18
Q

T. unguium: Four major clinical presentations

A

Distal sublingual onychomycosis: the most common form of the disease. Nail thickens, and often discolors.-get rid of nail as much as possible

Proximal sublingual onychomycosis: the most common form found in patients with HIV. inf. begins in the nail fold (cuticle)- do CD4+ test, screen for HIV (g24 Ag), TB: TBT or Quantiferon GOLD (if immigrant)

White superficial onychomycosis (Leukonychia mycotica): Nails lose their luster, become opaque, brittle, and have a crumbling consistency.

Candidal onychomycosis: (NOT a dermatophytic manifestation). typically colored: green or brown, unlike white usually associated with fungal

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19
Q

why should T. unguium dx be confirmed before tx?

A

requires expensive, prolonged tx (3-4mos for fingernail infections and 4-6mos for toenail infections)

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20
Q

?? of the clipped, distal free edge of the nail and attached subungual debris is the most sensitive diagnostic method for T. unguium and is painless for patients

A

Periodic acid-Schiff (PAS) staining with histologic examination

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21
Q

T. unguium ddx

A 
Trauma
lichen planus, 
psoriasis, 
nail-bed tumor, 
peripheral vascular disease, 
atopic dermatitis, 
contact dermatitis
yellow nail syndrome.
22
Q

Tinea corporis (tinea glabrosa) agents

A

Dermatophyte infections of glabrous (smooth) skin excluding certain
specific areas is caused by any of the Trichophyton or Microsporum species.
similar lesions to Tinea pedis, may look like a flower “iris-like”

23
Q

T. corporis clinical manifestations

A

Typically appears as single or multiple, annular, scaly lesions with central clearing, a slightly elevated, reddened edge, and sharp margination (abrupt transition from abnormal-to-normal skin) on the trunk, extremities, or face.
The border of the lesion may contain pustules or follicular papules.
Itching is variable.

24
Q

T. corporis ddx

A 
Nummular eczema,   
pityriasis rosea,         
Lyme disease, 
tinea versicolor,       
contact dermatitis,  
granuloma annulare 
psoriasis,                      
shingles?                       
impetigo 
*Herpes gladiatorum (also cause by CA-MRSA)
just S. aureus (secondarily impetiginous)

if scrape lesions w. no pain to pt, consider leprosy

25
Q

Tinea barbae (Barber’s itch) agents

A

Caused by anthropophilic strains of T. rubrum and zoophilic strains of T. mentagrophytes or T. verrucosum.

26
Q

T. barbae risk factor

A

shaving

27
Q

T. barbae clin manifest

A

Parallel bacterial folliculitis and sycosis barbae produced by S. aureus with associated alopecia and scaring.

28
Q

T. barbae ddx

a clue to dx??

A

bacterial folliculitis, perioral dermatitis, pseudofolliculitis barbae, contact dermatitis and herpes simplex. (mala furfur folliculitis)

typically hair removal is painless in tinea barbae (and other fungal) but painful in bacterial infections.

29
Q

Tinea faciei presentation

A

non-bearded area of the face.
itching and burning, which become worse after sunlight exposure
Some round or annular red patches are present. red areas may be indistinct, especially on darkly pigmented skin, and lesions may have little or no scaling or raised edges.

30
Q

for T. faciei dx, ?? and ?? may help in establishing the diagnosis.

A

A high index of suspicion, along with a KOH microscopy of scrapings from the leading edge of the skin change

31
Q

T. faciei ddx

A

seborrheic dermatitis, rosacea, discoid lupus erythematosus, psoriasis and contact dermatitis.

32
Q

Tinea capitis (Ringworm of the scalp and hair) agents

A

Microsporum or Trichophytonspecies
M. audouinii and M. canis are responsible for most infections in US.
Fungus grows distally, producing an ectothrix that fluoresces under Wood’s lamp.

33
Q

T. capitis age??

A

Occurs most often in children, rarely reported in individuals past puberty.

34
Q

T. capitis confirmed by culture in 92% of children

who had at least 3 of 4 of the following clinical features: ??

A

scalp scaling,
scalp pruritus,
occipital adenopathy,
diffuse, patchy, or discrete alopecia.

35
Q

four stages of T. capitis infection

A

incubation period is 2-4 d
enlargement of lesion which lasts 3-4 months
refractory period when no new lesions develop, last 4 months to years
lesions gradually regress

36
Q

severity of T. capitis infection will depend on

A

whether the strain is anthropophilic or not.

37
Q

T. capitis: M. audouinii and M. canis. Symptoms include ??

A

itchy, scaly scalp and papules develop. Infected hair becomes dull, breaks off 3 to 4 mm above the scalp (ectothrix).

38
Q

T. capitis: Trichophyton manifestations

A

T. tonsurans and T. violaceum produce “blackdot” endothrix infections, (i.e., fungus produces spores inside the hair shaft, and the infected hair break off at scalp level [black dot syndrome]).
(scalp and hair infections are on the increase in the US)

39
Q

T. capitis dx

A

Fluorescence with a Wood’s lamp for Microsporum sp. (ectothrix). Hair has spores on outside of the shaft. Spores on the inside of hair shaft – endothrix (Trichophyton)

listen at about 38 1/15…where hair breakage

40
Q

T. capitis ddx: When scaling and inflammation are prominent, other diagnoses to consider include ??

A 
seborrheic dermatitis (no hair loss), 
atopic dermatitis (lesions in flexural folds of the neck, arms, or legs), and 
psoriasis (nail changes and silvery scales on the knees or elbows)
41
Q

T. capitis ddx: When alopecia is prominent, diagnoses to rule out include ??

A 
alopecia areata (complete, rather than patchy, hair loss), 
traction alopecia (history of tight hair braiding), and
trichotillomania (hairs of differing lengths and a history of obsessive hair manipulation).
42
Q

Tinea favosa (Honeycomb ringworm) agent??
what is it??
what usually present??

A

T. schoenleinii (endothrix)

a chronic mycotic infection of the scalp or glabrous skin characterized by the formation of yellow crusts within the hair follicles (scutula) and eventual cicatricial alopecia and scarring. A “mousy” or “cheesy” odor is usually present.

43
Q

Dermatomycosis: Cutaneous Candidiasis is ??

agent?

A

Any fungal infection of the skin, nails or hair by a fungus OTHER THAN a dermatophyte.
Candida albicans

44
Q

Cutaneous Candidiasis incidence??

transmission??
age?? gender??

A

Parallels that of population with depressed cellular
immunity

part of normal flora
extremes of age, females

45
Q

Cutaneous Candidiasis risk factors

A

Diabetes, *obesity, pregnancy, antibiotics, steroids, AIDS, depressed CMI, PMN and/or transferrin function/levels.
v. old and v. young
can cause enathem and exanthem

46
Q

Cutaneous Candidiasis: Intertriginous candidosis

A

Characteristic “weeping” or “scaled skin” lesions. Typical lesions are pruritic, erythematous with macerated edges and frequently has satellite vesicopustules.
-hard to ddx from dermatophyte, should see germ tubes (pseudohyphae) if candida on microscopy

47
Q

Cutaneous Candidiasis: : Paronychial or onychomycotic candidosis

A

Characteristic painful, reddened swelling up to 1 cm from the paronychial edge.
nail is invaded in chronic infections; it becomes hardened, thickened, discolored (brownish or green), and striated with ridges or grooved.
Generally there is cuticle involvement +/- pus.
whole area involved, erythematous

48
Q

Cutaneous Candidiasis dx

A

KOH preparation of skin or nail scrapings and culture of skin or nail scrapings on
Sabouraud-glucose agar containing
chloramphenicol and cycloheximide and/or germ-tube test (candida is positive)

49
Q

Cutaneous Candidiasis tx

A

1% crystal violet (As good or better than 1% nystatin)

50
Q

Treat candidal paronychia or onychomycosis with ??

A

nystatin ointment,
amphotericin B ointment or
ketoconazole ointment and/or systemically (ampB, ketoconazole)

-opt for ketoconazole before amp B as it is very toxic

Micro (61 decks)

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