Skin bacterial abscess in Adult
Lesions evolve over days to 1-2 weeks. They are usually painful / tender, erythematous, warm, and fluctuant masses that are sometimes associated with fever. A tender subcutaneous nodule with overlying erythema but minimal fluctuance may be an early presentation. Incision and drainage is the mainstay of therapy. In an otherwise healthy, ambulatory patient, the addition of antibiotics is not indicated. Indications for the addition of antibiotics may include patients who are systemically ill, have a high burden of disease (indicated by concomitant widespread folliculitis or associated cellulitis), are immunosuppressed, or have failed incision and drainage.
Methicillin-resistant S. aureus (MRSA) first emerged as an important nosocomial pathogen in the 1960s. In more recent years, community-acquired outbreaks of MRSA (CA-MRSA) have increasingly been described among healthy individuals lacking the traditional risk factors for such infections (intravenous [IV] drug use, incarceration, participation in contact sports, etc). These strains have a propensity for causing abscesses, furunculosis, and folliculitis and have a unique antibiotic susceptibility profile from health care-associated strains of MRSA (HA-MRSA).
It has been shown that the majority of purulent skin and soft tissue infections presenting to emergency rooms across the United States are caused by CA-MRSA.
L02.91 – Cutaneous abscess, unspecified
31928004 – Abscess of skin AND/OR subcutaneous tissue
Differential Diagnosis & Pitfalls
- Kerions on the scalp are fungal-induced hypersensitivity reactions, commonly associated with adenopathy, and difficult to tell from bacterial-induced abscesses.
- Mycobacterial infections present as a "cold abscess" (little to no erythema or warmth) in a normal host.
- Ruptured epidermoid cyst
- Inflamed or infected epidermal inclusion cyst
- Foreign body reactions or foreign body granulomas
- Hidradenitis suppurativa
- Necrotizing fasciitis – If considered, this is a medical emergency.
- Panniculitis – Infectious or noninfectious cause of panniculitis.
The differential diagnosis of a tender, erythematous dermal or subcutaneous nodule in the immunosuppressed host must include bacterial, fungal, and mycobacterial organisms. These cannot be differentiated clinically and must be cultured to determine the causative organism.