Fungi and Infestations Flashcards

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1
Q

What is a dermatophyte?

A
  • Fungi that require keratin for growth
  • most common cause for fungal skin infections
  • They proliferate in stratified squamous epithelium
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2
Q

What are the different types of dermatophytes and what infection do they cause?

A

Microsporum, Trichophyton (most common), Epidermophyton

Tinea, classified on whereabouts it is on the body

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3
Q

Name the infection?

A

Tinea Pedis

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4
Q

Name the infection?

A

Tinea Cruris

Groin folds or anal cleft

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5
Q

Name the infection?

A

Tinea Corporis

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6
Q

Name the infection?

A

Tinea unguium

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7
Q

Name the infection?

A

Tinea manuum

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8
Q

Name the infection?

A

Tinea capitis

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9
Q

What investigations should you do for a suspected fungal infecton?

A
  1. Skin scrappings (skin from the advancing age is scraped)
  2. Nail clippings
  3. Hair clippings for infections which enter the shaft of the hair

Then Microscopy and Culture

Can do wood’s light for Microsporum Canis & M. Audouinii

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10
Q

What is wood’s light?

A

Wood’s light is a UV light. Certain fungi fluoresece under this light and therefore it used in the lab.

For microsporum canis & microsporum Audouinii

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11
Q

How would you treat localised skin infections?

A

With topical treatments:

  • Terbinafine
  • Azoles (e.g ketoconazole)
  • Polyenes (e.g. nystatin)
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12
Q

What is the 1st line treatment for dermatophyte infecions and why?

A

Terbenafine

Adverse side effects are rare

Can be given orally or topically

Most effective

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13
Q

How long would you treat with terbenafine for in the following infections: skin, fingernails, toe nails?

A

Skin 2 weeks

Finger nails 6 weeks

Toe nails 12 weeks

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14
Q

Name the different azoles which are topical and which are systemic?

A

Ketoconazole (topical, systemically can cause gynaecomastia)

Fluconazole (systemic)

Itraconazole (systemic)

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15
Q

What are the important points regarding Griseofulvin?

A

Fungistatic

Therefore long duration

Skin/hair 6 weeks

Toenails 6-12months

Only antifungal licensed in under 12’s

It is a hepatic enzyme inducer and can cause a photosensitive rash

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16
Q

What are common differentials for tinea?

A

Psoriasis nail changes note no pitting in tinea unguium

Discoid eczema (more itchy and no area of central clearing)

Erythasma more erythematous and again no clearing

17
Q

Describe the important diagnostic characteristics of candidiasis?

A

Candidiasis aka thrush

Around the mouth, genitals and nails

Erythematous rash which tends to spread from the folds, important features is that there tends to be red satelite papules or pustules around the edge of teh eruption.

18
Q

Who does candidiasis most commonly effect and what is the treatment?

A
  • Young and elderly
  • Immunocompromised
  • Diabetics
  • Those on steroids or antibiotics

It is treated with:

  • Azoles if it is a localised infection aka fluconazole, clotrimazole
    • Or
  • Polyenes if it is a systemic infection nyastatin, amphocterecin B
19
Q

What skin conditions are associated with Malassezia sp. (pitysporum) and where is this microbe found?

A

It is a commensal microbe on everyones skin and can cause the following conditions if it invades the epidermis:

Pityriasis Versicolor

Seborrhoiec dermatitis

20
Q

How does pityriasis versicolor present?

A

Finely scaly yellowish or brown macules, which develop into hypo or hyper pigmenented patches present on the trunk.

21
Q

What is the treatment of pityriasis versicolor?

A

Treated with topical antifungals:

  • Myconazole or terbinafine
  • Selenium sulphide shampoo

More extensive Itraconazole orally for 1 week or for immunosupressed

22
Q

Describe seborrhoeic dermatitis?

A

It is a mild eczematous condition which affects the face scalp and flexures.

In mild forms if it affects the scalp its coloquial name is dandruff.

23
Q

Describe the treatment of seborrhoeic dermatitis?

A

1st line:Topical azoles

For quick short term resoloution : Topical corticosteroids

For disease which can only be treated by corticosteroids long term: Topical immunomodulators (tacrolimus)

24
Q

Describe what causes scabies and how it is transmitted?

A

It is caused by the mite: Sarcoptes scabei

It is transmitted by human contact not in clothing

25
Q

How is scabies charcacterised?

(presentation and signs and common sites)

A

Presentation:

  • Red itchy papules which quickly become excoriated (sensitization to mite/products)

Signs:

  • You may also see linear burrow tracts, more burrows the longer the infestation.
  • Erythematous papules

Common sites:

  • finger webs, flexure, breasts, waist , ankles and feet
  • Scabies may become crusted in immunocompromised*
26
Q

How is scabies treated?

A

Using a scabicide such as:

  • permetherin (leave on for 8-12 hours)
  • Malathion (leave on for 24 hours)
  • Repeat both after 24 hours

All close contacts must be treated simulataneously

Note itching may continue due to post scabeitic eczema

27
Q

Describe how head lice presents?

A

Presents with itching

Signs may be:

Nits (eggs) or live lice in the hair

Erythema excoriation and papules around the hair.

28
Q

What is the treatment for head lice?

A

Fine combing

An appropriate hair conditioner (check local guidelines as reccomendations change)

Pediculocides - malathion, permethrin, carbaryl

29
Q

What is the lesion?

A

Candidiasis

Satelite lesions next to main eruption

30
Q

What is the lesion?

A

Nummular dermatitis (aka discoid ezcema)

(Not tinea as no central clearing)

31
Q

What is the lesion?

A

Seborrhoiec dermatitis/eczema

32
Q

What is the lesion?

A

Pityriasis versicolor

33
Q

What is the lesion?

A

Erythasma

No central clearing not tinea cruris

No satelite lesions not candidiasis

34
Q

What is the lesion?

A

Scabies

Excoriation marks (always check finger and toe webbs)