What treatment is needed for a patient with a history of cellulitis treated with Keflex (Cephalexin) a couple of months ago?

Management After Recent Cellulitis Treatment

If the patient has no current signs of active infection, no treatment is needed—focus on preventing recurrence through addressing predisposing factors and considering prophylactic antibiotics only if recurrent episodes occur despite preventive measures. 1

Current Clinical Assessment

Determine if active infection is present:

• Look for erythema, warmth, swelling, tenderness, or advancing borders of inflammation 2
• Assess for systemic signs including fever, tachycardia, or altered mental status 2
• If no active infection exists, this is a surveillance visit requiring preventive counseling, not antibiotics 1

If No Active Infection: Prevention Strategy

Address underlying predisposing conditions that increase recurrence risk:

Skin and Lymphatic Management

• Examine interdigital toe spaces for tinea pedis (athlete's foot) and treat aggressively with antifungals 1
• Keep skin well-hydrated with emollients to prevent dryness and cracking that serve as bacterial entry points 1
• Manage chronic edema through elevation of extremity, compressive stockings, pneumatic pressure pumps, or diuretic therapy if appropriate 1
• Treat venous eczema ("stasis dermatitis") if present 1

Prophylactic Antibiotics for Recurrent Cellulitis

Consider prophylaxis ONLY if frequent infections occur despite the above measures:

• Monthly intramuscular benzathine penicillin 1.2 million units in adults 1
• Oral penicillin V 1 g twice daily 1
• Oral erythromycin 250 mg twice daily 1

The evidence for prophylactic antibiotics is mixed, so this should be reserved for patients with documented recurrent episodes (typically ≥3-4 per year) despite optimal preventive measures 1.

If Active Infection is Present

Reassess the clinical scenario as this represents treatment failure or recurrence:

Evaluate for Treatment Failure Indicators

• Spreading erythema despite 48-72 hours of appropriate antibiotics 3
• New purulent drainage suggesting MRSA involvement 2, 3
• Systemic toxicity including fever >38°C, tachycardia >90 bpm, hypotension, or confusion 2, 3
• Severe pain out of proportion to examination raising concern for necrotizing fasciitis 2

Treatment Algorithm for Active Infection

For typical nonpurulent cellulitis without MRSA risk factors:

• Cephalexin 500 mg four times daily for 5 days if clinical improvement occurs 2, 4
• Beta-lactam monotherapy succeeds in 96% of cases 2, 4
• Do NOT add MRSA coverage reflexively—combination therapy with trimethoprim-sulfamethoxazole plus cephalexin provides no additional benefit 4

For cellulitis with MRSA risk factors (purulent drainage, penetrating trauma, injection drug use):

• Clindamycin 300-450 mg three times daily provides both streptococcal and MRSA coverage 2, 3
• Alternative: Doxycycline 100 mg twice daily PLUS a beta-lactam (never doxycycline alone) 2

For severe infection with systemic toxicity:

• Hospitalize immediately 2, 3
• Vancomycin 15-20 mg/kg IV every 8-12 hours PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours 2
• Obtain emergent surgical consultation if necrotizing fasciitis suspected 2

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for resolved cellulitis—this promotes resistance without benefit 5
• Do not assume MRSA is the problem in typical nonpurulent cellulitis—streptococci cause the majority of cases even in high-MRSA-prevalence settings 2, 4
• Do not ignore predisposing factors—each cellulitis episode causes permanent lymphatic damage, and recurrence risk increases without addressing underlying conditions 1
• Do not use cephalexin if Lyme disease is possible—it has poor activity against Borrelia burgdorferi and will allow disease progression 6
• Avoid concurrent acid suppressive therapy with cephalexin—this may reduce efficacy, with failure rates of 40% versus 20% for other antibiotics 7

Adjunctive Measures for Active Infection

• Elevate the affected extremity to promote gravity drainage of edema and inflammatory mediators 1, 2
• Consider systemic corticosteroids (prednisone 30 mg with 8-day taper) in non-diabetic adults to hasten resolution by approximately 1 day 1, 3
• Add NSAIDs (ibuprofen 400 mg every 6 hours for 5 days) as adjunctive therapy to shorten time to complete resolution 8