Superficial, Mycoses

Front 1

Describe presentation of dermatophyte infections

Back 1

slowly progressive eruptions of the skin & appendages
unsightly, not painful or life threatening.
manifestations vary, depending on inflammatory response
typically involve erythema, induration, itching, and scaling.

Front 2

What are th characteristics of the common dermatophytes?

Back 2

Form septate hyphae, macroconidia, and microconidia
morphology of conidia are basis for seperation

Front 3

What are the major species that cause dematophyte infections?

Back 3

Epidermophyton, Microsporum, and Trichophyton are major genera

Front 4

Describe transmission of dermatophytes? What is the port of entry?

Back 4

low virulence and requires prolonged contact for human2human otherwise from animal or soil
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Port of entry is typically throuh minor skin breaks

Front 5

What does tinea mean in latin? How is it used in medicine?

Back 5

worm
it is used to describe skin infection in medicine

Front 6

What type of tissues do dermatophytes spread to?

Back 6

pread from skin to other keratinized structures, such as hair and nails, or may invade them primarily
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The hair shaft can be invaded and broken by hyphae
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Black piedra. Note invasion by Piedraia hortae both within (endothrix) and outside (exothrix) the hair shaft. Dermatophyte invasion would be similar

Front 7

What is important immunological response to dermatophytes?

Back 7

Th1 mediated by T cells is important
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Phagocytes are able to use oxidative pathways to kill the fungi both intracellularly and extracellularly

Front 8

When might dermatphyte infections become widespread

Back 8

immunocompormised host w/ poor Th1 response

Front 9

What are the names for the sites of dermatophyte infections? (7)

Back 9

tinea capitis (scalp; Figure 44–3A),
tinea pedis (feet, athlete's foot),
tinea manuum (hands),
tinea cruris (groin),
tinea barbae (beard, hair),
and tinea unguium (nail beds).
not included in this list are called tinea corporis (body)
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Tinea capitis. A. Ringworm of the scalp with superficial lesions and loss of hair. B. Close-up using an ultraviolet lamp (Wood's light) reveals fluorescing hair fragments. The culture grew Microsporum audouinii.

Front 10

What are the steps in tinea capitis?

Back 10

Erythematous paupule surrounding follicle -> scaling of scalp -> discoloration -> fracture of follicle -> Spread to adjacent follicles in ring manner
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Symptoms rare beyond hair loss and itching

Front 11

What are the favorable conditions for fungi?

Back 11

moist areas and skin folds. Tight clothing

Front 12

What is athletes foot?

Back 12

scaling and splitting of the skin between the toes, is commonly known as athlete's foot. Moisture and maceration of the skin provide the mode of entry.

Front 13

How do you diagnose dermatophytes? What is the goal>

Back 13

Take scrapings from periphery of lesion.
KOH mounts of skin scrapings and infected hairs demonstrate hyphae. Some will fluoresce under wood's lamp
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The goal is to differentiate from bacterial and parasitic infections

Front 14

Do we culture dermatophytes?

Back 14

Generally no, does not change clinical management.
If KOH mount is negative then culturing is required

Front 15

How are dermatophyte infections treated?

Back 15

Generally topical is enough.
Nail bed or more extensive dermatophyses may require systemic treatment

Front 16

What rxs are used in the topical treatment? the systemic treatment?

Back 16

Topical tolnaftate, allylamines, or azoles usually sufficient
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Systemic griseofulvin or azoles used in refractory cases

Front 17

Describe the typical sporotrichosis infection

Back 17

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Sporotrichosis. A. This infection began on the finger and has started to spread up the arm, leaving satellite lesions behind. If untreated, these lesions will evolve into ulcers. B. A more advanced case beginning with inoculation in the foot.

Front 18

What are the subcutaneous fungal infection disease types? what about the etiologies?

Back 18

Sporotrichosis - singel etiology = sporothrix schenkii
Chromoblastomycosis - caused by multiple fungi
Mycetoma - caused by multiple fungi

Front 19

What about the fungi SPOROTHRIX SCHENCKII? Why melanin?

Back 19

Dimporphic, hyphae are thin and septated, conidia clusters at end of hyphae, synthesizes melanin
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Melanin resists oxidative killing

Front 20

What is pathogenesis of sporotrichosis?

Back 20

Injection of conidia to subQ tissue (thorn) -> Painless papule -> grows and ulcerates -> drains in lymphatics -> jumping nodules along lymph drainage pathway

Front 21

What do conidia and yeast cells bind to in SubQ infections?

Back 21

Fungi bind to Extracellular proteins
fibronectin, laminin, colagen

Front 22

What is definitive diagnosis for Sporotrichosis?

Back 22

Culture of infected pus/tissue and demonstration of typical conidia & dimorphism

Front 23

What is the treatment for Sporotrichosis?

Back 23

Itraconazole though more invasive pulmonary/systemic may require in addtion Amphoterocin B
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Azole - 14 demethylase inhibitor in ergosterol synthetic pathway
Ampho - pore forming at Ergosterol site

Front 24

Describe chromoblastomycosis?

Back 24

1. Disease occurs typically on the foot or leg. It appears as papules that develop into scaly, pigmented, wart-like structures, usually under the feet.
2. Occurs people walk barefoot in tropics
3. No lymph involvement
4. Slow & painless

Front 25

How treat chromoblastomycosis? What are most common agents?

Back 25

Surgery and antifungal therapy.
Flucytosine & Itraconazole

Front 26

What is mycetoma?

Back 26

Clnical term for infection of foot associated w/ trauma that inoculates wound. May also be caused by actinomyces/nocardia

Front 27

Describe clinical presentation of mycetoma? How about treatment

Back 27

A massive induration with draining sinuses
Once established, the treatment of mycetoma is difficult