Skin infections Flashcards

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1
Q

What is cellulitis?

A

Bacterial infection of the skin

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2
Q

What is the most common causative organism of cellulitis?

A

Strep. pyogenes

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3
Q

What can predispose people to cellulitis?

A

Oedema/poor circulation in the legs

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4
Q

How does cellulitis typically present?

A
  • infected area is red, hot & swollen
  • pyrexia
  • general malaise
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5
Q

Investigations for cellulitis?

A

Bacterial swab

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6
Q

Management of cellulitis?

A

Flucloxacillin 1st line
Doxycycline if pen allergic
Vancomycin if MRSA

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7
Q

What is necrotising faciitis?

A

Life threatening soft tissue infection, basically a deeper and more serious cellulitis

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8
Q

Explain the pathophysiology of necrotising faciitis?

A

extensive tissue necrosis and toxaemia

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9
Q

What is the most common causative organism of necrotising faciitis?

A

Strep. pyogenes - around wounds/post-surgery

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10
Q

How does necrotising faciitis typically present?

A
  • out of proportion pain (excruciating pain under a wound that doesn’t look that impressive)
  • crepitations when skin is felt (air in skin)
  • signs of infection: fever, tachycardia, hypotension
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11
Q

How is necrotising faciitis treated?

A

Immediate surgical debridement and antibiotics

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12
Q

What is impetigo?

A

V contagious superficial bacterial infection that usually affects the face in children

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13
Q

What is the most common cause of impetigo?

A

Staph aureus

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14
Q

How does impetigo typically present?

A

Red lesions with a yellow/gold crust, usually on the face

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15
Q

Management of impetigo?

A

1st line = topical fusidic acid 7 days

extensive/severe = oral flucloxacillin

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16
Q

What is staphylococcal scalded skin syndrome?

A

Blistering condition due to toxins released by certain strains of staph aureus, usually in children under 5

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17
Q

Explain the pathophysiology of staphylococcal scalded skin syndrome?

A
  • Toxins from certain strains of staph aureus bind to desmosomes in the skin and break them up so that keratinocytes become unstuck
  • This splits the epidermis at the granular layer and creates blisters
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18
Q

How does staphylococcal scalded skin syndrome typically present?

A
  • red, blistering skin (looks like burns)
  • tender & painful
  • superficial epidermis peels off in sheets
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19
Q

Management of staphylococcal scalded skin syndrome?

A

IV flucloxacillin

Supportive treatment - fluid & electrolyte balance & pain relief

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20
Q

What is ringworm?

A

A fungal (dermatophyte) infection of the skin

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21
Q

What is the most common causative organism for ringworm and what type of transmission is it passed on by?

A

Trichophyton rubrum

Human-human transmission

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22
Q

What are the 2nd and 3rd most common causative organisms for ringworm and what type of transmission are they passed on by?

A
2nd = trichophyton mentagraphytes (human-human)
3rd = microsporum canis (cats/dogs-human)
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23
Q

What is tinea capitis?

A

Ringworm in the scalp

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24
Q

What is tinea barbae?

A

Ringworm in the beard

25
Q

What is tinea corporis?

A

Ringworm on the body

26
Q

What is tinea unguium?

A

Ringworm around the nails

27
Q

What is tinea cruris?

A

Ringworm in the groin

28
Q

What is tinea pedis?

A

Ringworm in the foot - also known as athletes foot

29
Q

How does ringworm typically present?

A

itchy red skin

lesions have a ring appearance - grows outwards and has a healed centre

30
Q

Management of ringworm?

A

Clotrimazole (canesten cream topically)

31
Q

What is scabies?

A

intensely itchy rash which is spread by close contact

32
Q

What causes scabies?

A

Sarcoptes scabiei

33
Q

What is the incubation period for scabies?

A

6 weeks

34
Q

How does scabies typically present?

A

Intensely itchy rash in finger webs, wrists and genital areas
Can see where the mites have burrowed in the skin

35
Q

Management for scabies?

A

Malathion lotion

36
Q

What is chickenpox?

A

Infection from the Varicella Zoster Virus (chickenpox is caused by the varicella part, shingles is caused by the zoster part)

37
Q

Explain how zoster virus latency can lead to shingles in old age in someone who has had chickenpox?

A

The virus establishes latency in nerve roots and can be reactivated in old age which causes shingles in that dermatome

38
Q

At what point is chickenpox no longer infectious?

A

when the vesicles become scabs

39
Q

What is shingles?

A

Reactivation of varicella zoster virus

40
Q

Explain the pathophysiology behind shingles?

A

Virus is dormant in dorsal root ganglion of a nerve once chickenpox is gone
When reactivated the infected nerve and surrounding tissues become inflamed
Dermatomal distribution

41
Q

How does singles typically present?

A

single dermatome affected
neuralgic pain (feels like ants crawling under the skin)
erythema & blisters - then crusts over

42
Q

Management of singles?

A

aciclovir

43
Q

What is Ramsay-Hunt Syndrome?

A

Herpes Zoster virus infection of the facial nerve (CN VII) and irritation of vestibulocochlear nerve (CN VIII)

44
Q

What is the difference between Bells Palsy and Ramsay hunt syndrome?

A

bells palsy = facial palsy with no rash

Ramsay hunt = more severe palsy with rash

45
Q

How does Ramsay-Hunt Syndrome typically present?

A
  • Painful vesicles in ear canal, throat and tongue
  • Facial palsy
  • If CN VIII is affected: deafness, tinnitus & vertigo
46
Q

Management of Ramsay-Hunt Syndrome?

A

Aciclovir

47
Q

What infections does Type 1 HSV (herpes simplex virus) cause?

A

Oral and genital

48
Q

What infections does Type 2 HSV (herpes simplex virus) cause?

A

Genital

49
Q

What is primary gingivostomatitis?

A

Self limiting painful ulceration around the mouth in pre-school children, caused by HSV type 1

50
Q

What is molluscum congagiosum?

A

fleshy, pale nodules in children that are caused by skin to skin contact

51
Q

What is the causative organism for molluscum contagiosum?

A

Molluscum contagiosum virus

52
Q

What are warts caused by?

A

Human Papilloma Virus types 1-4

53
Q

What is the treatment for warts?

A

topical salicylic acid

54
Q

What is hand, foot and mouth disease?

A

painful vesicles on palms, soles and mouth due to coxsackie virus. Self limiting

55
Q

What is syphilis?

A

STI that can affect the skin - can be primary and secondayr

56
Q

What is the difference between primary and secondary syphilis affecting the skin?

A
Primary = chancre - painless ulcer at point of entry
Secondary = red rash all over body with snail track ulcers on mucous membranes
57
Q

Investigations for syphilis?

A

PCR swab of ulcers

58
Q

Which type of ulcers are more likely to form on the foot/mid shin?

A

Arterial ulcers

59
Q

Which type of ulcers are more likely to form on the medial/lateral malleolus?

A

Venous ulcers