Skin and Soft Tissue Infections Flashcards
What are some of the bacteria that make up the normal skin flora?
- Coagulase negative staph,
- Corynebacterium,
- S. Aureus,
- S. pyogens,
- Fungi
Describe features of impetigo
- Presents with golden encrusted skin lesions with inflammation localised to epidermis. It can be contagious.
- Caused by S. aureus and can be treated with topical fusidic acid or systemic abx if required
What is Tinea and its features
- Superficial fungal infections of the skin/nails.
- Caused by microsporum, epidermophyton and other fungi.
- Diagnosed via skin scrapings
- Treatment of non-severe cases - topical clotrimoxazole or terbinafine cream. Systemic therapy required in severe cases and this can be terbinafine
What are soft tissue abscesses?
- Infection within dermis/fat layers with development of walled off infection and pus.
- Limited antibiotic penetration into abscess so best treatment is surgical drainage with Abx use if not fully drained/surrounding cellulitis.
Describe features of cellulitis
- Infection involving the dermis, commonly caused by S. aureus and group A strep (beta-haemolytic strep)
- Often tracks through lymphatic system and may be associated with systemic upset
What is the classification of cellulitis
Ero classification:
Class I - No signs of systemic toxicity or uncontrolled comorbidities.
Class II - Person is systemically unwell or has comorbidities.
Class III - Person has severe systemic upset or unstable comorbidities.
Class IV - Person has severe infection/sepsis
Explain the treatment of cellulitis
Class I - Oral flucloxacillin or 2nd line oral doxycycline/clarithromycin for 7 days.
Class II - Short term hospitalization for IV Abx followed by discharge on outpatient parental abx therapy (OPAT). 1st line is IV flucloxacillin or 2nd line IV vancomycin.
Class - III/IV urgent hospital admission and consideration of surgical management.
What are some complications of cellulitis?
- Severe tissue destruction or septic shock. Therefore regular clinical review is important.
What is streptococcal toxic shock and the treatment
- Caused by toxins released by group A strep which is normally involved in primary infection within throat or skin/soft tissue. Patients often have diffuse, faint rash over body/limbs.
- Treatment is surgery for abscesses, antibiotics (penicillin and clindamycin to reduce toxin production) and consider pooled human immunoglobulin
What is necrotising fasciitis and its signs and symptoms
- Life threatening soft tissue infection with deep tissue involvement.
- Surgical emergency which requires extensive surgical debridement
- Signs/symptoms: Pain out of proportion to the clinical signs, severe systemic upset, presence of visible necrotic tissue, imaging may show fascial oedema and gas in soft tissue
What are the two types of necrotising fasciitis
Type 1 - Polymicrobial which usually complicates existing wounds. Mix of gram -ve, gram +ve and anaerobes.
Type 2 - Group A streptococcus which usually occurs in previously healthy tissue, typically on limbs following minor injury. Strep pyogens.
What is the treatment for necrotising fasciitis
- Surgical emergency - surgical debridement
- Broad spec abx: Flucloxacillin, benzylpenicillin, gentamycin, clindamycin and metronidazole. All 5, consider vancomycin if pt has MRSA history
What bacteria are commonly found in bite injuries?
- Staphylococcus,
- Streptococci,
- Anaerobes,
- Pasteurella and capnocytophagia from mammal mouth
What is the treatment for bite injuries?
Abx therapy: 1st line co-amoxiclav or 2nd line doxycycline and metronidazole.
Surgical treatment: Consider early exploration and debridement.
Prophylaxis: Abx, tetanus prophylaxis and rabies prophylaxis (if bat scratches/bites)
What are the risks of people who inject drugs?
They often present late with neglected soft tissue infection. There is high risk of bacteraemia and disseminated infections (S. aureus bacteraemia, DVT and multiple pulmonary abscesses)
