What is the first-line treatment for skin abscesses?

First-Line Treatment for Skin Abscesses

Incision and drainage (I&D) is the cornerstone and primary treatment for skin abscesses, and for simple, uncomplicated abscesses, I&D alone without antibiotics is sufficient therapy. 1, 2

Primary Treatment: Incision and Drainage

• I&D is the most important therapeutic intervention and is recommended for all cutaneous abscesses, large furuncles, and carbuncles regardless of size. 1, 3
• The surgical site should be covered with a dry dressing after drainage—this is usually the easiest and most effective wound care approach. 1, 2
• Packing the wound with gauze does not improve healing compared to simply covering with sterile gauze and causes more pain, though some clinicians still use this technique. 1
• For very small furuncles, application of moist heat may promote spontaneous drainage and could be sufficient without formal I&D. 2

Critical technical point: Large abscesses should be drained with multiple counter incisions rather than one long incision to prevent step-off deformity and delayed wound healing. 1, 3

When Antibiotics Are NOT Needed

For simple superficial abscesses, antibiotics are not needed after adequate I&D if the following criteria are met: 1, 2

• Induration and erythema are limited only to the defined area of the abscess and do not extend beyond its borders 1
• The abscess does not extend into deeper tissues or have multiloculated extension 1
• No systemic signs of infection (temperature <38.5°C, pulse <100 beats/minute, leukocytes <12,000 cells/µL) 3
• Patient is immunocompetent 1, 2
• Source control is complete after drainage 1, 2

Research supports this approach: a pediatric study showed that I&D without adjunctive antibiotics was effective for CA-MRSA abscesses <5 cm in immunocompetent children. 4

When to Add Antibiotics to I&D

Antibiotics should be added as adjunctive therapy when any of the following are present: 1, 2

Systemic Inflammatory Response Syndrome (SIRS) Criteria:

• Temperature >38°C or <36°C 1, 2
• Tachypnea >24 breaths/minute 1, 2
• Tachycardia >90 beats/minute 1, 2
• White blood cell count >12,000 or <400 cells/µL 1, 2

Other High-Risk Features:

• Markedly impaired host defenses or immunocompromised patients 1, 2
• Significant surrounding cellulitis extending beyond abscess borders 1, 2
• Incomplete source control after drainage 1, 2
• High-risk anatomic locations (face, hands, genitalia) 2
• Abscess size >5 cm (associated with higher hospitalization risk) 4

Antibiotic Selection When Indicated

When antibiotics are warranted, coverage must address MRSA in most community settings: 1, 2

First-Line MRSA-Active Agents:

• Trimethoprim-sulfamethoxazole (TMP-SMX) 320/1,600 mg twice daily 2, 5
• Clindamycin 1, 2
• Doxycycline or minocycline (avoid in children <8 years) 2

Duration of Therapy:

• 7-10 days for MRSA infections 2, 6
• A 10-day course of TMP-SMX is superior to 3 days for MRSA abscesses, reducing both treatment failure (by 10.1%) and recurrence within 1 month (by 10.3%) 6
• 5-10 days is typical when antibiotics are indicated 2

Important evidence: Two large randomized trials demonstrated that TMP-SMX improved outcomes across all lesion sizes and regardless of guideline antibiotic criteria, with treatment effect greatest in patients with history of MRSA infection, fever, and positive MRSA culture. 5

For Non-MRSA Infections:

• Beta-lactams (penicillinase-resistant penicillins or first-generation cephalosporins) when streptococci are suspected 1, 2

Complex Abscesses Requiring Different Management

Complex abscesses (perianal, perirectal, IV drug injection sites) require I&D plus empiric broad-spectrum antibiotics covering Gram-positive, Gram-negative, and anaerobic bacteria if: 1, 3

• Systemic signs of infection are present 1, 3
• Patient is immunocompromised 1, 3
• Source control is incomplete 1, 3
• Significant cellulitis surrounds the abscess 1, 3

What NOT to Do

• Do not attempt needle aspiration as primary treatment—it has only 25% overall success rate and <10% success with MRSA infections. 1, 7
• Do not rely on antibiotics alone without drainage—this will fail and allow progression. 8
• Do not routinely culture simple abscesses unless there is recurrence, treatment failure, immunocompromise, or severe/atypical presentation. 2

Common Pitfalls

• Failing to perform adequate I&D with thorough evacuation of pus and breaking up of loculations 3
• Not considering MRSA coverage when antibiotics are indicated in areas with high MRSA prevalence 2
• Using ineffective antibiotics—in one study, only 7% of patients received an antibiotic to which their CA-MRSA isolate was susceptible before culture results 4
• Overlooking underlying conditions predisposing to recurrent abscesses 2