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Micro Exam 3 > Dermatomycoses: superficial infections > Flashcards

Dermatomycoses: superficial infections Flashcards

1
Q

How are dermatophytes transmitted?

A

Direct contact with spores, or infested hair or skin scales

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2
Q

Pathogenesis of dermatomycoses

A

Spores adhere to keratinized tissue (epidermis) –> germinate –> secrete keratinases –> invade/grow
WITHOUT eliciting host immune response (nondestructive/asymptomatic)

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3
Q

Four kinds of superficial dermatomycosis infections:

A 
Hair of the scalp:
1) black piedra
2) white piedra
Hairless skin:
3) tinea/pityriasis versicolor
4) tinea/pityriasis nigra
*Tinea = infection of hairless skin*
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4
Q

What is the cause of pityriasis versicolor?

A

The yeast, malassezia furfur.

The yeast is lipophilic and grows best in warm temperatures/humidity.

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5
Q

Where in/on the skin does the infection of malassezia furfur take place?

A

Stratum corneum

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6
Q

Clinical presentation of pityriasis versicolor?

A

Look up some pics! (I thought these were just sun spots..)
Brownish red and de-pigmented lesions, scaly patches of skin
Usually affect the trunk most
No inflammation/no itch.
Relapse is frequent.

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7
Q

How do we diagnoses pityriasis versicolor?

A

Yellow-green fluorescence (in keeping with the italian theme of sketchy, I like to think pesto-ish) on examination by Wood’s lamp …
oOoOh ambiance.

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8
Q

Treatment for pityriasis versicolor

A

Topical: selenium sulfide shampoo, other options for shampoos and lotions, topical terbinafine, and/or benzoyl peroxide

For shampoos- leave in for 10 minutes then wash out, repeat for 7 days, then once a month for 6 months.

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9
Q

If patient isn’t responding to primary pit. versi. treatment…

A

go with systemic therapy (ketoco-, fluco-, or itraconazole)

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10
Q

What is the cause of pityriasis nigra? Where does it infect?

A
  • Exophiala werneckii

- Stratum Corneum again

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11
Q

Clinical presentation of tinea nigra

A

Pictures pictures!
most are asymptomatic but…
-Brown to black NONSCALY macules with well-defined borders
-Palm surfaces are most affected

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12
Q

Where are tinea nigra infections most common?

A

Tropical climates and frequent contact with decaying vegetation, wood, soil

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13
Q

Diagnose tinea nigra, please.

A

Treat a superficial scraping with KOH

Look for abundant branched septate/fragmented hyphae

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14
Q

Treatment for tinea nigra

A

Oral azoles

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15
Q

Cutaneous dermatomycoses are also known as:

A

Ringworm: infection of superficial keratinized tissues, hair, skin, and nails

… slightly deeper in the epidermis than superficial mycosis

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16
Q

What is the ONLY contagious fungal infection?

A

Dermatophytosis

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17
Q

Three genera of dermatophytes (species in parentheses)

A

Microsporum (audouinii)
Epidermophyton (floccosum)
Trichophyton (rubrum, tonsurans, mentagrophytes, schoenleinii)

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18
Q

Dermatophytes are classified according to mode of transmission. What are the three kinds?

A

1) Geophilic-from soil
2) Zoophilic- from animals
Both of these produce acute inflammatory infections in humans; easily treated

3) Anthropophilc- from humans
Produce mild to chronic infxn; difficult to eradicate

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19
Q

3 diagnostic clues for dermatophytes

A

1) presence of septate
2) branching hyphae
3) chains of arthroconidia

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20
Q

Identifiying microsporum

A

Ectothrix- dense sheath of spores around hair

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21
Q

Identifying trichophyton

A

Endothrix- produce arthroconidia inside hair shaft

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22
Q

Identifying epidermophyton

A

BANANA BUNCHES (thin-walled macroconidia)

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23
Q

Name the body part that goes with the type of tinea!

Capitis, Pedis, Barbae, Corporis, Ungulum, Manus, Cruris

A
  • Head
  • Feet
  • Beard
  • Body
  • Nail
  • Fingers/palm
  • Crotch (jock itch)
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24
Q

Most common cause of tinea capitis?

A

Trichophyton tonsurans

Scaly lesions on scalp, eyebrows, eyelashes

25
Q

Epidemiology and at risk people for tinea capitis

A
  • Children 4-14 y.o.
  • Classmates
  • Family members
  • Overcrowded areas, poor hygiene, and protein mulnurished
26
Q

Treatment for Tinea capitis

A

Griseofulvin and Ketoconazole

27
Q

2 infectious agents for Tinea barbae

A
  • T. mentagrophytes (a beard is “meant ta grow” wink wink)

- T. verrucosum

28
Q

Who is most commonly affected by Tinea barbae?

A

Adult men in frequent contact with cattle, dogs, other animals (dairy farmers and cattle ranchers)
Barbershop guys

29
Q

Clinical presentation of Tinea barbae

A

Endothrix- diffuse erythema and perifollicular papules and pustules
-Inflammatory type is usually unilateral and spares the upper lip; nodular lesions covered with cursts; hair becomes brittle

30
Q

Treatment for Tinea barbae?

A

Systemic antifungal agents.

31
Q

Causes of Tinea corporis and Tinea faciei?

A
  • Trichophyton rubrum

- Microsporum canis

32
Q

Clinical presentation of Tinea corporis and Tinea faciei?

A

Active erythematous ring with spreading borders with a cleared center on hairless regions of skin and face
Inflammatory and Non-inflammatory lesions

33
Q

Treatment for inflammatory Tinea corporis and Tinea faciei?

A

Systemic therapy progression: Ketoconazole, itraconazole, terbinafine, griseofulvin

34
Q

Just a reminder: as the name implies, M. canis can be transmitted by direct contact with infected animals, humans, or contaminated clothing

A

:)

35
Q

The sciencey name for athlete’s foot is…

A

Tinea pedis = ringworm of the foot especially in between toes

36
Q

Frequent causes of Tinea pedis?

A
  • Epidermophyton floccosum

- Trichophyton rubrum

37
Q

Clinical presentation of Tinea pedis?

A

Vesicular or ulcerative… super itchy. kinda looks like dead skin

38
Q

Epidemiology of Tinea pedis?

A

Common in athletes, related to footwear, common showers, and pool floors.

39
Q

Treatment of Tinea pedis?

A

Systemic therapy progression: Ketoconazole, itraconazole, terbinafine, griseofulvin

40
Q

This is getting boring…let’s talk about Jock itch. (where and cause)

A

aka Tinea Cruris = ringworm of the groin, perineum and perianal region
Mostly caused by E. Floccosum

41
Q

What does jock itch look like?

A

Sharp demarcated lesions with raised erythematous margin, lesions in genitocrural area and medial upper thigh, scrotum hardly affected.

42
Q

Can you get jock itch from indirect contact with contaminated objects?

A

Yes so try not to share gym towels, or gym equipment. Trust no one at the gym.

43
Q

Treatment for Tinea cruris?

A

Topical treatments

44
Q

Treatment for non-inflammatory Tinea Corporis?

A

Topical treatments

45
Q

Cause and treatment for Tinea manus?

A

T. rubrum

Treat with topicals

46
Q

What is onychomycosis?

A

Infection of the nail plate seen in tinea ungulum

47
Q

Three common causes of Tinea ungulum?

A

T. rubrum (as in corporis, faciei, and manus)
T.mentagrophytes (as in barbae)
E. floccosum (as in pedis and cruris)

48
Q

Who is at risk of developing Tinea ungulum?

A

Elderly with reduced peripheral circulation, diabetics, those with increased nail trauma
Chronic water exposure
Poor hygiene
Immunodeficient

49
Q

Treatment for Tinea ungulum?

A

Systemic antifungals.

50
Q

Name the only subcutaneous mycosis that we talked about and its cause.

A

Sporotrichosis caused by sporothrix schenckii.

51
Q

Who is most at risk for developing sporotrichosis?

A

People who work with soil and vegetation (i.e. flower shop employees)

52
Q

Sporothrix Schenckii is dimorphic meaning…

A

Mold in the cold, yeast in the heat.
Room temp: branching septate hyphae with microcondia
In the body: elongated yeasts

53
Q

What are two buzz word plants for sporotrichosis?

A

Sphagnum moss and roses

54
Q

Pathogenesis of sporotrichosis

A

NOT spread person to person.
-Enter through thorn prick or splinter (needs an opening)
OR
-Rarely, inhaling conidia –> pulmonary infection

55
Q

How long does it take for sporotrichosis symptoms to appear after exposure?

A

1-12 weeks

56
Q

What are the four categories of sporotrichosis?

A

1) Lymphocutaneous (most common)
2) Pulmonary (rare)
3) Osteoarticular -direct inoculation or haematogenous seeding in bones
4) Disseminated (rare)- cutaneous lesions and multiple visceral organ involvement; most common in AIDS pts.

57
Q

Describe the progression of lymphocutaneous sporotrichosis

A

= inflamed pusy subcutaneous nodules progressing proximally along lymph channels
Small painless bump resembling insect bite –> one or more additional boil-like nodules spread along lymph –> eventually lesions look like open sores
Very slow to heal

58
Q

Treatment for sporotrichosis:

A

Prolonged therapy of itraconazole or fluconazole for cutaneous lesions.
Amph B for relapses and serious infections

Micro Exam 3 (11 decks)

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