skin and soft tissues infections
Skin and Soft Tissues
Introductions
Types of skin infections:
- Purulent: usually staph
- abscess
- furuncles
- carbuncles
- Nonpurulent: usually beta-hemolytic strep
- erysipelas
- cellulitis
- necrotizing skin infections
Erysipelas and Cellulitis
- Erysipelas: epidermis, upper dermis, superficial lymphatics
- Cellulitis: deeper dermis, subcutaneous fat tissues
Differential diagnosis:
- contact or stasis dermatitis
- lymphadema
- erythema nodosum
- DVT
- thrombophlebitis
- lipodermatosclerosis
- erythromelalgia
- hypersensitivity reactions
Diagnosis
- Blood cultures: positive 5%. Not routinely used
- Skin aspirate/biopsy: consider
- Imaging: not helpful but can use to exclude necrotizing infection
Treatment
- Surgical debridement: necrotizing infection, bullae, desquamation
- Duration: 5 days and extend as necessary until improvement
- Ppx: Consider penicillin or erythromycin for patients with >3 episodes annually
- Stasis dermatitis
- Stasis dermatitis is caused by fluid buildup due to varicose veins, circulation issues, or heart disease.
- Skin discoloration of the ankles or shins, itching, thickened skin, and open sores (ulcers) are symptoms.
- Treatments may include compression stockings and prescription creams as well as treating the underlying condition.
Necrotizing Fasciitis
- subdermal compartments: fascia, muscle
- usually spreads along superficial fascia
- usually occur with previous skin trauma/infection, extremities more often
- risk factors: DM, IVDU, malignancy, liver disease, immunocompromised
- liver disease: V. vulnificus especially
- DM: NF of perineum, Fournier gangrene
- bacteria: Streptococcus pyogenes, Staphylococcus aureus, Streptococcus agalactiae, Aeromonas hydrophila, Vibrio vulnificus, and Clostridium perfringens.
- LRINEC score for risk indicator
Bullous cellulitis characteristic of Vibrio vulnificus infection is shown in a patient with cirrhosis; cutaneous necrosis is also evident, most likely associated with disseminated intravascular coagulation.
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Sx:
- initially resembles cellulitis
- rapid progression with edema, severe pain, bullous lesion, skin necrosis, crepitus, anesthesia
- SIRS
- characteristics: "woody" induration with palpation
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Labs: nonspecific
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Imaging:
- gas in soft tissues
- MRI > xray/CT
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Treatment
- empiric: aerobic and anaerobic organisms (including MRSA) and consists of vancomycin, daptomycin, or linezolid plus piperacillin-tazobactam, a carbapenem, ceftriaxone plus metronidazole, or a fluoroquinolone plus metronidazole. Some experts also recommend adding empiric clindamycin because of its suppression of toxin production by staphylococci and streptococci.
- Antimicrobial discontinuation can be considered when the patient is afebrile and clinically stable, and surgical debridement is no longer required.
Purulent Skin Infections
- Abscess: pus collection in dermis, subcutaneous fat
- Furuncles: boils. Hair follicle associated abscess into dermis/subcutaneous tissues
- Carbuncle: extension subcutaneously with several furuncles
- Treatment
- I&D
- Gram stain and culture with drainage
- MRSA: decolonization with topical intranasal mupirocin and chlorhexidine washes