What is the best treatment approach for a patient presenting with fever, irritability, and a red, warm, painful, tender swelling in the lower leg, without pus or abscess, and with stable vitals?

Treatment Recommendation for Lower Leg Cellulitis

This patient requires oral flucloxacillin with close outpatient follow-up (Option B), as they present with uncomplicated cellulitis without systemic instability or features requiring hospitalization.

Clinical Presentation Analysis

This patient demonstrates classic non-purulent cellulitis of the lower leg with:

• Localized signs of infection (erythema, warmth, pain, tenderness, spreading) 1
• Fever and irritability (systemic response) 1
• Stable vital signs (no hemodynamic instability) 1
• No abscess or purulent collection (no surgical indication) 2
• No signs of necrotizing infection or compartment syndrome 2

Why Oral Antibiotics Are Appropriate

Stable vital signs are the key determinant that allows outpatient oral therapy rather than IV hospitalization 1. The Infectious Diseases Society of America framework suggests hospital admission only for hemodynamic instability, severe symptoms, or inability to tolerate oral medications 1.

Oral Flucloxacillin (Floxacillin) Is the Correct Choice

• First-line agent for non-purulent cellulitis targeting Staphylococcus aureus and Streptococcus pyogenes 3, 4
• Excellent oral bioavailability and tissue penetration 3
• Standard dosing: 500-1000 mg four times daily for 7 days 4
• Recent evidence shows high-dose cephalexin (1000 mg QID) reduces treatment failure rates to 3.2% versus 12.9% with standard dosing 4

Why NOT the Other Options

Option A (Oral + Topical Antibiotics): Incorrect

• Topical antibiotics have no role in established cellulitis 2
• Topical therapy is only considered for superficial wound colonization or very mild infections, not spreading cellulitis with systemic symptoms 2
• Adding topical agents provides no additional benefit and may increase resistance risk 2

Option C (IV Antibiotics + Surgical Consultation): Inappropriate Escalation

• IV antibiotics are reserved for 2:
  • Hemodynamically unstable patients
  • Inability to tolerate oral medications
  • Failed oral therapy
  • Deep abscesses or necrotizing infections
• Surgical consultation is indicated for 2:
  • Deep abscesses or compartment syndrome (absent here)
  • Necrotizing soft tissue infections (no clinical evidence)
  • Gas gangrene or systemic sepsis (vitals are stable)

This patient has none of these indications 2, 1.

Critical Follow-Up Requirements

Close outpatient monitoring is essential because cellulitis can progress despite appropriate therapy 1, 4:

• 48-72 hour reassessment to evaluate treatment response 4
• Mark the borders of erythema to track progression 1
• Return precautions for worsening symptoms, spreading infection, or development of systemic instability 1
• Treatment failure occurs in 3-13% of cases even with appropriate antibiotics 4

Common Pitfalls to Avoid

• Don't delay antibiotics waiting for cultures in uncomplicated cellulitis—blood cultures are rarely positive and don't change management 1
• Don't add MRSA coverage empirically unless there are specific risk factors (IV drug use, known colonization, recurrent infections) 2
• Don't use topical antibiotics for established cellulitis—they don't penetrate adequately 2
• Don't hospitalize stable patients—this increases healthcare costs without improving outcomes 1, 4