Fungi and Infestations

Question 1

What is a dermatophyte?

Answer 1

A dermatophyte is a class of fungi, which are the most common cause for fungal skin infections.

They proliferate in stratified squamous epithelium.

Question 2

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

Answer 2

Microsporum, Trichophyton, Epidermophyton

Tinea, classified on whereabouts it is on the body

Question 3

Name the infection?

Answer 3

Tinea Pedis

Question 4

Name the infection?

Answer 4

Tinea Cruris

Groin folds or anal cleft

Question 5

Name the infection?

Answer 5

Tinea Corporis

Question 6

Name the infection?

Answer 6

Tinea unguium

Question 7

Name the infection?

Answer 7

Tinea manuum

Question 8

Name the infection?

Answer 8

Tinea capitis

Question 9

What investigations should you do for a suspected fungal infecton?

Answer 9

Skin scrappings (skin from the advancing age is scraped)

Nail clippings

Hair clippings for infections which enter the shaft of the hair

Microscopy and culture.

Question 10

What is wood’s light?

Answer 10

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

Question 11

How would you treat localised skin infections?

Answer 11

With topical treatments:

Terbinafine

Azoles

Polyenes

Question 12

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

Answer 12

Terbenafine

Adverse side effects are rare

Can be given orally or topically

Question 13

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

Answer 13

Skin 2 weeks

Finger nails 6 weeks

Toe nails 12 weeks

Question 14

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

Answer 14

Ketoconazole (topical, systemically can cause gynaecomastia)

Fluconazole (systemic)

Itraconazole (systemic)

Question 15

What are the important points regarding Griseofulvin?

Answer 15

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

Question 16

What are common differentials for tinea?

Answer 16

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

Question 17

Describe the important diagnostic characteristics of candidiasis?

Answer 17

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.

Question 18

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

Answer 18

Young and elderly

Immunocompromised

Diabetics

Those on steroids or antibiotics

It is treated with:

Azolees if it is a localised infection aka fluconazole, clotrimazole

Or

Polyenes if it is a systemic infection nyastatin, amphocterecin B

Question 19

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

Answer 19

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

Pityriasis Versicolor

Seborrhoiec dermatitis

Question 20

How does pityriasis versicolor present?

Answer 20

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

Question 21

What is the treatment of pityriasis versicolor?

Answer 21

Treated with topical antifungals:

Miconazole

Selenium sulphide shampoo

More extensive Itraconazole orally

Question 22

Describe seborrhoeic dermatitis?

Answer 22

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.

Question 23

Describe the treatment of seborrhoeic dermatitis?

Answer 23

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)

Question 24

Describe what causes scabies and how it is transmitted?

Answer 24

It is caused by the mite: Sarcoptes scabei

It is transmitted by human contact not in clothing

Question 25

How is scabies charcacterised?

Answer 25

Red itchy papules which quickly become excoriated.

Common sites: finger webs, flexure, breasts, waist , ankles and feet

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

Scabies may become crusted in immunocompromised

Question 26

How is scabies treated?

Answer 26

Using a scabicide such as: permetherin

Must be applied for 8-12 hours and treat on days 1 and 8.

All close contacts must be treated simulataneously.

Bed linen and clothing should be washed.

Note itching may continue due to post scabeitic eczema

Question 27

Describe how head lice presents?

Answer 27

Presents with itching

Signs may be:

Nits (eggs) or live lice in the hair

Erythema excoriation and papules around the hair.

Question 28

What is the treatment for head lice?

Answer 28

Fine combing

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

Question 29

What is the lesion?

Answer 29

Candidiasis

Satelite lesions next to main eruption

Question 30

What is the lesion?

Answer 30

Nummular dermatitis

(Not tinea as no central clearing)

Question 31

What is the lesion?

Answer 31

Seborrhoiec dermatitis/eczema

Question 32

What is the lesion?

Answer 32

Pityriasis versicolor

Question 33

What is the lesion?

Answer 33

Erythasma

No central clearing not tinea cruris

No satelite lesions not candidiasis

Question 34

What is the lesion?

Answer 34

Scabies

Excoriation marks (always check finger and toe webbs)