Skin and soft tissue infections

Question 1

What are some routes of infection?

Answer 1

• Skin - pores, hair follicles
• Wounds - scratches, cuts, burns
• Bites - insects, animals

Question 2

What are the three main layers of the skin?

Answer 2

• Epidermis
• Dermis
• Hypodermis

Question 3

What should be included in the history of a patient when investigating a skin infection?

Answer 3

• The onset, evolution, duration and location of lesions
• Contacts with a similar rash
• Past medical history noting skin conditions such as eczema or immunosuppression
• Skin trauma or abrasions or bites
• Previous treatment including antimicrobial therapy
• Systemic features such as fever

Question 4

How is cellulitis managed in primary care?

Answer 4

• Class I cellulitis - draw a line around the lesion, prescribe high-dose oral antibiotics according to local guidelines
• Pain relief and elevation
• Deal with concomitant skin lesions
• Provide patient information on cellulitis
• Refer patients with recurrent cellulitis
• Review in 48 hours

Question 5

When is referral needed when managing cellulitis?

Answer 5

• Part of an outbreak
• Diagnostic uncertainty
• Resistant to maximal treatment
• Complications

Question 6

What hygiene measures would you advise to aid healing and prevent spreading of a skin disease?

Answer 6

• Wash affected areas with soap and water
• Wash their hands regularly, in particular after touching a patch of impetigo
• Avoid scratching affected areas
• Avoid sharing towels

Question 7

What skin layer do different infections affect?

Answer 7

• Impetigo - epidermis
• Erysipelas - epidermis and upper dermis
• Cellulitis - dermis and lower epidermis
• Necrotising fasciitis - all bar the top part of epidermis

Question 8

What are some fungi that can cause skin infections?

Answer 8

Dermatophytes

• tinea spp
• e.g tinea pedis
• e.g tinea corporis
• e.g tine cruris

Yeasts

• candida albicans
• malassezia furfur

Question 9

What are some viral infections of the skin and name some clinical signs of the infections

Answer 9

• Human papilloma viruses (HPV) - warts
• Herpes simplex virus 1 (HSV1) - cold sores
• Herpes simplex virus 2 (HSV2) - genital warts
• Varicella zoster virus (VZV) - chicken pox, shingles
• Coxsackie A virus - hand, foot and mouth disease

Question 10

Describe the sarcoptes scabiei (scabies mite)

Answer 10

• Causes scabies
• Mite burrows into skin
• Female lays eggs
• Infection is asymptomatic
• Hypersensitivity may occur
• May lead to super infection

Question 11

Describe the epidemiology of animal bites

Answer 11

• 250000 cases A&E UK/year
• Dogs make up 80-90% of bites followed by cats the humans
• More common in children than adults
• Site: children - facial/cervical (neck) Adults - extremities

Question 12

What percentage of each animal’s bite causes infection?

Answer 12

Cat - 80%
Dog - 36%
-Human - 18%

Question 13

Describe a cat bite

Answer 13

• Small deep wound - 2-5cm
• Usually periphery
• Pasturella spp infection - pasturella multocida
• Cellulitis possible

Question 14

Describe a dog bite

Answer 14

• Large wound: tearing and crushing
• Usually periphery but can occur anywhere
• Secondary infections: large area damaged, high chance of contamination
• Crush damage comes with its own complication
• Surgery required if extensive superficial damage and crushing

Question 15

Describe a human bite

Answer 15

• Wide shallow wound
• Can occur anywhere on the body
• Highly polymicrobial
• Deep infection is common, viral infection

Question 16

What is the animal bite mantra?

Answer 16

The solution to pollution is dilution

Question 17

What does the animal bite mantra mean?

Answer 17

Washing out the wound is the best way to prevent infection of the body