Fungi and Infestations Flashcards
What is a dermatophyte?
A dermatophyte is a class of fungi, which are the most common cause for fungal skin infections.
They proliferate in stratified squamous epithelium.
What are the different types of dermatophytes and what infection do they cause?
Microsporum, Trichophyton, Epidermophyton
Tinea, classified on whereabouts it is on the body
Name the infection?
Tinea Pedis
Name the infection?
Tinea Cruris
Groin folds or anal cleft
Name the infection?
Tinea Corporis
Name the infection?
Tinea unguium
Name the infection?
Tinea manuum
Name the infection?
Tinea capitis
What investigations should you do for a suspected fungal infecton?
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.
What is wood’s light?
Wood’s light is a UV light. Certain funghi fluoresece under this light and therefore it used in the lab.
How would you treat localised skin infections?
With topical treatments:
Terbinafine
Azoles
Polyenes
What is the 1st line treatment for dermatophyte infecions and why?
Terbenafine
Adverse side effects are rare
Can be given orally or topically
How long would you treat with terbenafine for in the following infections: skin, fingernails, toe nails?
Skin 2 weeks
Finger nails 6 weeks
Toe nails 12 weeks
Name the different azoles which are topical and which are systemic?
Ketoconazole (topical, systemically can cause gynaecomastia)
Fluconazole (systemic)
Itraconazole (systemic)
What are the important points regarding Griseofulvin?
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
What are common differentials for tinea?
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
Describe the important diagnostic characteristics of candidiasis?
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.
Who does candidiasis most commonly effect and what is the treatment?
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
What skin conditions are associated with Malassezia sp. (pitysporum) and where is this microbe found?
It is a commensal microbe on everyones skin and can cause the following conditions if it invades the epidermis:
Pityriasis Versicolor
Seborrhoiec dermatitis
How does pityriasis versicolor present?
Finely scaly yellowish or brown macules, which develop into hypo or hyper pigmenented patches present on the trunk.
What is the treatment of pityriasis versicolor?
Treated with topical antifungals:
Miconazole
Selenium sulphide shampoo
More extensive Itraconazole orally
Describe seborrhoeic dermatitis?
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.
Describe the treatment of seborrhoeic dermatitis?
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)
Describe what causes scabies and how it is transmitted?
It is caused by the mite: Sarcoptes scabei
It is transmitted by human contact not in clothing
How is scabies charcacterised?
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
How is scabies treated?
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
Describe how head lice presents?
Presents with itching
Signs may be:
Nits (eggs) or live lice in the hair
Erythema excoriation and papules around the hair.
What is the treatment for head lice?
Fine combing
An appropriate hair conditioner (check local guidelines as reccomendations change)
What is the lesion?
Candidiasis
Satelite lesions next to main eruption
What is the lesion?
Nummular dermatitis
(Not tinea as no central clearing)
What is the lesion?
Seborrhoiec dermatitis/eczema
What is the lesion?
Pityriasis versicolor
What is the lesion?
Erythasma
No central clearing not tinea cruris
No satelite lesions not candidiasis
What is the lesion?
Scabies
Excoriation marks (always check finger and toe webbs)
