What is the treatment for an infected bump on the leg?

Treatment of an Infected Bump on the Leg

For an infected bump on the leg, immediately assess the severity of infection and initiate appropriate antibiotic therapy combined with proper wound care, including debridement of necrotic tissue and off-loading of pressure if applicable.

Initial Assessment and Severity Classification

The first critical step is determining infection severity, which dictates the entire treatment approach 1:

• Assess depth of tissue involvement: Look for involvement of deeper structures (fascia, muscle, bone) versus superficial skin only 1
• Check for systemic signs: Fever, leukocytosis, metabolic instability (hyperglycemia, acidosis), or hemodynamic compromise 1
• Evaluate for limb-threatening features: Extensive necrosis, gangrene, crepitus, necrotizing infection, or critical ischemia 1
• Examine for deep abscess: Fluctuance, severe tenderness, or dorsal erythema with plantar wound suggests deep compartment involvement 1

Antibiotic Selection Based on Severity

Mild Infections

For mild superficial infections with minimal surrounding cellulitis, use narrow-spectrum oral antibiotics targeting aerobic gram-positive cocci 1:

• Dicloxacillin 125-250 mg every 6 hours on an empty stomach (1 hour before or 2 hours after meals) 2
• Duration: 1-2 weeks, continuing at least 48 hours after fever resolves and symptoms clear 1
• Topical antimicrobial therapy may be considered for very mild superficial infections 1

Moderate to Severe Infections

Broad-spectrum parenteral antibiotics are required initially for moderate-to-severe infections 1:

• Cover gram-positive cocci (including MRSA if locally prevalent), gram-negative organisms, and obligate anaerobes 1
• Parenteral therapy ensures adequate tissue concentrations, especially in ischemic tissue 1
• Duration: 2-4 weeks for moderate/severe soft tissue infections, depending on adequacy of debridement and tissue vascularity 1

Essential Wound Care Components

Antibiotic therapy alone is insufficient—proper wound care is crucial for healing 1:

• Debride all necrotic and callused tissue before obtaining culture specimens 1
• Off-load pressure from the affected area to promote healing 1
• Select appropriate dressings based on wound characteristics 1:
  • Hydrogels or continuously moistened saline gauze for dry/necrotic wounds
  • Alginates or foams for exudative wounds
  • Hydrocolloids to facilitate autolysis and absorb exudate

Culture and Microbiological Evaluation

Obtain cultures from debrided wound base using curettage or biopsy, not superficial swabs 1:

• Cleanse and debride before specimen collection 1
• Avoid swabbing undebrided ulcers or drainage 1
• Blood cultures are indicated for severe infections or systemic illness 1
• Cultures may be unnecessary for acute mild infections in antibiotic-naive patients 1

Surgical Consultation Criteria

Seek urgent surgical consultation for any of the following 1:

• Deep abscess or compartment syndrome
• Extensive bone/joint involvement
• Crepitus or necrotizing fasciitis
• Substantial necrosis or gangrene
• Critical limb ischemia
• Plantar wound with dorsal erythema (suggests fascial compartment penetration) 1

Early surgery (within 24-48 hours) combined with antibiotics reduces major amputation rates in moderate-to-severe infections 1.

Hospitalization Indications

Hospitalize patients with any of the following 1:

• Systemic toxicity (fever, leukocytosis)
• Metabolic instability (severe hyperglycemia, acidosis)
• Rapidly progressive or deep-tissue infection
• Substantial necrosis, gangrene, or critical ischemia
• Need for urgent diagnostic/therapeutic interventions
• Inability to perform self-care or inadequate home support

Follow-up and Monitoring

Re-evaluate within 3-5 days (or sooner if worsening) for outpatients 1:

• If infection fails to respond, consider discontinuing antibiotics for several days, then obtain optimal culture specimens 1
• Continue antibiotics until infection resolves, not necessarily until wound heals 1
• Monitor for complications requiring surgical intervention 1

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for uninfected wounds—this does not improve healing and promotes resistance 1
• Do not delay surgical debridement while awaiting revascularization in ischemic limbs 1
• Do not rely solely on absence of fever/leukocytosis to rule out severe infection—50% of limb-threatening infections lack systemic signs 1
• Do not use superficial swabs from undebrided wounds—these yield unreliable results 1