Fungi and infestations

Question 1

What are the 3 categories of fungal infections?

Answer 1

Superficial - epidermis

Deeper infections - dermis + subcutaneous tissue

Systemic infections

Question 2

What are the most common causative fungi seen in dermatology?

Answer 2

Dermatophytes

Question 3

What are the three genera of dermatophytes?

Answer 3

microsporum

trichophyton (most common)

epidermophyton

Question 4

Through what do dermatophytes invade and live in?

Answer 4

Keratinised stratified squamous epithelium

Question 5

What are potential reservoirs of dermatophytes?

Answer 5

humans

animals

soil

Question 6

What are the lay and medical terms for dermatophyte infection?

Answer 6

Lay - ringworm

Medical - tinea

Question 7

What types of tinea infection are there?

Answer 7

tinea corporis (tinea of the hairless skin)

tinea cruris (groin)

tinea manuum (hand)

tinea pedis (foot)

onychomycosis (tinea of the nails, a.k.a. tinea unguium)

tinea capitis (head)

Question 8

What is the most common type of tinea infection?

Answer 8

tinea pedis

Question 9

Which demographic is tinea capitis most common in?

Answer 9

Afro-Caribbeans due to increased genetic risk

Question 10

List diseases than can be confused with tinea?

Answer 10

Psoriasis

Nummular dermatitis

Erythrasma

Candidiasis

Question 11

How can psoriasis be differentiated from tinea?

Answer 11

In tinea there will NOT be nail pitting.

although onycholysis can occur in both

Question 12

Which areas are at risk of candida infection?

Answer 12

Mouth

Genitals

Around nails

Question 13

Which groups are particularly at risk of candida infection?

Answer 13

Young / Old

Immunosuppressed

Diabetics

On antibiotics / steroids

Question 14

What is the Ix of choice for suspected fungal skin infections?

Answer 14

Skin scraping (essentially any infested part of skin which can the be MC+S)

Question 15

What are the indications for systemic anti-fungals?

Answer 15

If nail,

scalp or

hair are infected

if a widespread skin infection

if immunocompromised

Question 16

What is the most effective agent for tinea (dermatophyte infection)?

Answer 16

Terbinafine

Question 17

Through what route are azoles metabolised?

Answer 17

Via the liver

Question 18

In which patients must you be careful prescribing systemic azoles to?

Answer 18

Those with poor liver function as the azole will thus be metabolised slower

Question 19

Which azole can be used as a shampoo?

Answer 19

Fluconazole

Question 20

Why is ketoconazole generally not used systemically?

Answer 20

As it inhibits androgen synthesis leading to gynaecomastia

Question 21

Why is griseofulvin rarely used anymore?

Answer 21

As it is more fungistatic than cidal

Question 22

For what is griseofulvin licensed for?

Answer 22

Orally treat Tinea

Question 23

What are the two adverse affects of griseofulvin?

Answer 23

Can induce a photosensative rash

Can cause drug interactions as is metabolised by the liver

Question 24

Is griseofulvin oral or topical?

Answer 24

Oral. It is ineffective topically

Question 25

What are the treatments for candidiasis?

Answer 25

Systemic --> Polyenes: Nystatin or Amphotericin B Topical --> Azoles: Clotrimazole or fluconazole

Question 26

What are malassezia furfur?

Answer 26

Commensal fungi (yeasts)

Question 27

What are the two cutaneous manifestations of malassezia furfur?

Answer 27

pityriasis vesicolor seborrhoeic dermatitis

Question 28

Who is pityriasis vesicolor commonly seen in the UK?

Answer 28

People coming home from holiday

Question 29

How common is relapse in pityriasis vesicolor?

Answer 29

Common to relapse

Question 30

How is Pityriasis vesicolor treated?

Answer 30

Topical antifungals Selenium shampoo Intraconzole

Question 31

How common is Seborrhoeic dermatitis?

Answer 31

Fairly common

Question 32

What is the typical distribution of seborrhoeic dermatitis?

Answer 32

Symmetrical on the face Scalp - cradle cap (in young children), dandruff (adults) Flexures

Question 33

What is the treatment for seborrhoeic dermatitis?

Answer 33

Topical azoles Low potency topical corticosteroids

Question 34

How does scabies spread?

Answer 34

Human to human contact | not via clothing or dirty toilet seats

Question 35

What is the severe form of scabies known as? (who is it seen in)

Answer 35

crusted scabies (seen in immuno-compromised or elderly patients) has a high mite load

Question 36

What are the signs of scabies infection?

Answer 36

Itchy papules (often excoriated) Burrows

Question 37

What is the inflammation in scabies caused by?

Answer 37

Mite faeces

Question 38

What is a unique physical sign of scabies in children? (and what causes it)

Answer 38

blistering of the palms and soles | due to stong host response to the infestation

Question 39

What is the treatment for scabies?

Answer 39

Permethrin for 12hrs or Malathion for 12hrs wash clothes and linen treat all contacts simultaneously (including health care workers)

Question 40

What is an adverse outcome post-scabies treatment? (how is it treated?

Answer 40

post-scabies eczema this is treated as per normal eczema

Question 41

What causes head lice?

Answer 41

pediculosis capitis

Question 42

What do pediculosis capitis feed on?

Answer 42

Feed on blood in the scalp

Question 43

What can pediculosis capitis transmit?

Answer 43

Transmit staph aureus & strep pyogenes

Question 44

How is pediculosis capitis transmited?

Answer 44

Human to human contact

Question 45

What are the signs of head lice?

Answer 45

pruritis eggs (nits) or live lice seen on hair erythema papules excoriations

Question 46

What is the treatment for pediculosis capitis?

Answer 46

Removal (hair conditioner, fine comb) Pediculicides (malathion) - this is not that effective

Question 47

How is tinea investigated?

Answer 47

Skin scraping Nail clippings/subungul debrisd Hair pluckings Wood's light (emits UV-A)

Question 48

What are the systemic antifungals?

Answer 48

Terbinafine Azoles (Itraconazole) Griseofulvin

Question 49

What are the topical antifungals?

Answer 49

Terbinafine Azoles (Ketoconazole) Polyenes (Nystatin)

Question 50

What are the sigde effects of terbinafine?

Answer 50

There arn't any common ones

Question 51

What are the signs of pityriasis vesicolor?

Answer 51

Hypo- or hyper-pigmented patches Mild scaling Mostly on the trunk