Skin and Sot Tissue Infections Flashcards
Discuss the skin as a defensive barrier
• Epidermis – hard horny layer of dead cells • Surface is dry • Constant sloughing • Acidic pH • Sweat secretion • Rich blood and lymphatic supply • Produces antimicrobial substances e.g. – fatty acids – sebum – defensins
What is an abscess?
collection of pus; pustule
What is a (cutaneous) vesicle?
blister; bullae (plural); fluid filled sac
What is pyoderma?
pus-forming skin infection; cutaneous abscess
What is impetigo?
vesicles developing into rupturing pustules then forming dried crusts
What is ecthyma?
rupturing vesicles leading to erythematous lesions and dried crusts
What is folliculitis?
inflammation at hair follicle
What is a furuncle?
boil; deep folliculitis
What is a carbuncle?
collection of boils
What is erysipelas?
erythema and inflammation of superficial dermis
What is cellulitis?
erythematous inflammation affecting deeper dermis and subcutaneous fat
What is ACNE?
infection of sebaceous follicles
What is necrotising fasciitis?
cellulitis with necrosis affecting skin, deeper fascia and sometimes muscle
What is dehiscence?
wound rupture along surgical suture
What are some normal skin microbiota?
• Coagulase-negative Staphylococci – Staphylococcus epidermidis – Staphylococcus aureus • Streptococcus pyogenes • Propionibacterium acnes • Corynebacterium sp. • Candida sp.
What are the routes of infection in the skin?
• Skin – Pores – Hair follicles • Wounds – Scratches – Cuts – Burns • Bites – Insects – Animals
List 4 skin infections in order of superficiality
Impetigo
Erysipelas
Cellulitis
Necrotising fasciitis
When taking a history about skin infection what should you ask abt?
• 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 insect bites.
• Previous treatment including antimicrobial therapy.
• Systemic features such as fever
Discuss management of skin infections in primary care
- 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. For example:
– Cellulitis or erysipelas published by the British Association of
Dermatologists (BAD, www.bad.org.uk).
– About cellulitis published by the Lymphoedema Support
Network (www.lymphoedema.org).
– Cellulitis published by NHS (www.nhs.uk).
– Refer patients with recurrent cellulitis
– Review in 48 hours
Discuss general management of skin infection
• Referral rarely needed unless - part of an outbreak
- diagnostic uncertainty
- resistant to maximal treatment
- complications e.g., acute glomerulonephritis
• Advise hygiene measures help to aid healing and stop infection spreading:
– Wash affected areas with soap and water.
– Wash their hands regularly, in particular after touching a patch
of impetigo.
– Avoids scratching affected areas.
– Avoids sharing towels etc.,
Are blood cultures necessary in skin infections?
Not always necessary but will take 24-48 to return so empiric therapy is usually required.
What are some comorbidities of skin infections
Diabetes mellitus
Cathater related infection
Name some fungal infections in the skin
• Dermatophytes – Tinea spp. – e.g. Tinea pedis – e.g. Tinea corporis – e.g. Tinea cruris • Yeasts – Candida albicans – Malassezia furfur
Name a parasite that can cause an infection?
Ringworm
How may ringworm present?
As ringworm of the skin and ringworm of the groin
What is a famous skin infection of the foot?
Athlete’s foot
Name some viral infections of the skin
- 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
What is the impact of sarcoptes scabei (mite)
– Causes scabies – Mite burrows into skin – Female lays eggs – Infection is asymptomatic – Hypersensitivity may occur – May lead to superinfection
Discuss the epidemiology of animal bites
– 250 000 cases A+E UK / yr • 3% visits – Dogs 80-90% > cat > human – Children > adults – Site • Children – facial / cervical • Adults – extremities
What should be considered in an animal bite?
What structures have been affected?
What part of the body is affected?
What (if any) infection is going to result? Any expected complications? Management?
Discuss cat bites
Small deep wound (2-5 cm)
Usually periphery (small mouths) (hand, foot) Pasteurella spp.
Cellulitis
Assess!
Discuss pasteurella multocida
• Animal commensal + pathogen
– Fowl cholera, swine atrophic rhinitis, RTI rabbits,
bovine septicaemia
I
V
• Zoonosis
– Bites, septic arthritis, septicaemia, meningitis, osteomyelitis
Discuss dog bites
Large wound: tearing, crushing
Usually periphery but can occur anywhere
Secondary infections: large area damaged, high chance of contamination (dog, environment)
Crush damage comes with its own complications
Surgery – extensive superficial damage and crushing
Discuss human bites
Wide shallow wound
Anywhere…
Highly polymicrobial
Deep infection is common, viral infection Drastically different- Assess
What is the animal bite ‘mantra’?
“The Solution to Pollution is Dilution”
Discuss the microbiology of bites?
• Polymicrobial! • Human – average 5 microorganisms will infect – 60% anaerobes – Eikenella corrodens 1⁄4 hand bites – Group A Strep (S. pyogenes) • Viral aetiology (risk assess) – rabies (remember bats!) – Simian herpes virus, – Hep B, HIV, Hep C
What are the important points of management of bites?
• Full history – immunodeficiency, country of exposure • Radiology – clenched fist, scalp bites (children) • Wound exploration – irrigate / debride = SOURCE CONTROL – delayed closure • Antibiotic therapy – prophylaxis – treatment
What length antibiotic course should be given for cellulitis?
7- 10 days
What length antibiotic course should be given for tenosynovitis?
21 days
What length antibiotic course should be given for septic arthritis?
28 days
What length antibiotic course should be given for osteomyelitis?
42 days
