Skin Infections and Infestations Flashcards

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1
Q

What is an infection?

A

Pathological state resulting from invasion of the body by pathogenic microorganisms

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2
Q

What lives on the skin?

A

Aerobic cocci - staphylococcus epidermidis and staphylococcus aureus
Corynebacterium and Propionibacterium
Yeats - Malassezia furfur

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3
Q

What are the signs of an infection?

A

Erythema, hot, tender, pus, exudate and fever

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4
Q

Does purulent skin problem mean there is infection?

A

No - can have sterile purulent
Signs of no infection - apyrexial, no rigors, long standing rash and no growth of pathogens on swab

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5
Q

What is impetigo?

A

Superficial skin infection
Most common bacterial skin infection in children
Can be bullous
Staph. aureus and strept pyogenes

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6
Q

What is the treatment for impetigo if localised?

A

Fusidic acid 2% cream 3-4 times daily for 5 days
Mupirocin 2% cream up to 3 times daily for 5 days (if MRSA)

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7
Q

What is the treatment for impetigo if widespread, severe or bullous?

A

Flucloxacillin 500mg oral 4 times daily for 7 days
Erythromycin 500mg oral 4 times daily for 7 days

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8
Q

What is the likely organism for cellulitis/ erysipelas?

A

Streptococcus pyogenes and staphylococcus aureus

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9
Q

What is the first choice antibiotic for cellulitis/ erysipelas?

A

Flucloxacillin 1g IV every 6hrs plus Benzylpenicillin 1.8g IV every 6hrs

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10
Q

What are some differential diagnosis for bacterial skin infections?

A

Deep vein thrombosis
Venous eczema
Allergic contact dermatitis
Necrotising fasciitis

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11
Q

What is the investigation and plan for bacterial infection?

A

Take swab - start antibiotics
Review after 48hrs - check skin swab result and switch according to sensitivities
If not better in a week then consider alternative diagnosis

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12
Q

Describe oedema blisters

A

Acute exacerbation of oedema can cause blisters to appear
Dorsum of feet
Often erythematous and can feel hot

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13
Q

Describe lipodermatosclerosis

A

If acute then can be hot and tender
Look for signs of venous disease and bilateral
Due to poor circulation in legs
Scarring and discolouration - hemosiderin depositions

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14
Q

What is the treatment for lipodermatosclerosis?

A

Treat underlying venous disease
Topical steroids

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15
Q

What are types of fungal infections?

A

Tinea (mould) - infection by dermatophyte
Candidiasis (yeast)

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16
Q

What are some different types of tinea?

A

Named by site affected
Ringworm or Tinea corporis if on body
Tinea capitis - head
Tinea pedis - athletes foot
Tinea cruris - groin
Onychomycosis - nails

17
Q

What is tinea manuum?

A

Fungal infection of the head
One hand suggests that the source is elsewhere
Hyper-linearity

18
Q

How is fungal infection diagnosed?

A

Skin scrapings

19
Q

What is the treatment for tinea?

A

Feet, body, hands or groin usually respond to topical treatment - Terbinafine or clotrimazole cream
Scalp or nails - oral anti-fungal
Check and treat other family members

20
Q

How is eczema differentiated between tinea?

A

History, distribution - eczema usually symmetrical and is extremely common, skin scrapings and tinea corporis or ringworm are rare

21
Q

What is a type of yeast causing fungal infection?

A

Candida albicans - likes warm and moist places like the flexures/ folds of skin

22
Q

What is the treatment of candida?

A

Nystatin, Miconazole and Ketoconazole cream

23
Q

Describe intertrigo

A

Superficial rash in folds of persons body - caused by yeast
Can be due to infection or skin condition
Most cases are secondary to friction and irritating effect of sweat
Emollient can often help

24
Q

What is the general advice for viral warts?

A

Contagious but the risk of transmission is low - children should not be excluded from activities but take care to minimise transmission

25
Q

What is the treatment for viral warts?

A

Normally not necessary
Wart paints and cryotherapy can stimulate immune system
Warts will go away when patient develops immunity against wart virus

26
Q

What is a cause of viral warts?

A

Human papilloma virus

27
Q

Describe molluscum contagiosum

A

DNA pox virus
Umbilicated papules
May become secondary infected
Will resolve when patient develops immunity

28
Q

What can help with treatment for molluscum contagiosum?

A

5% potassium hydroxide - can help give inflammatory response to help start immune system

29
Q

Describe herpes simplex virus (HSV)

A

Herpes simplex 1 and 2
Cold sores for type 1 and genitals affected in type 2
Eczema herpeticum can give widespread infections

30
Q

What is the treatment for HSV?

A

Aciclovir

31
Q

What is the presentation of herpes zoster virus?

A

Chicken pox in children - cranial to caudal spread and self-limiting
Shingles is the reactivation in adults

32
Q

What is a type of infestation?

A

Scabies - mites in human infection
Sarcoptes scabei

33
Q

Where about on body does scabies appear?

A

Web spaces, wrists, nipples, ankles and genitals

34
Q

What is a burrow and how is it good for diagnosis of scabies?

A

Burrow is mite path
For diagnosis a marker pen is drawn over bump and then wiped off - if burrow then ink will be there

35
Q

What is crusted scabies?

A

Thousands of mites - highly infectious
Hyper infestation which can occur in the immunocompromised

36
Q

How is scabies diagnosed?

A

Biopsy and have crust removed

37
Q

What is the treatment for scabies?

A

Permethrin cream top to toe for 8 hours - two applications 1 week apart
Oral ivermectin can be used - not in UK
Explain that itch may take 1-4 weeks to settle - treat symptomatically with steroids

38
Q

Does a positive swab always mean infection?

A

No - if eczema broken skin can hold bacteria