What is the recommended antibiotic treatment for an otherwise healthy individual with a bacterial skin and soft tissue infection, such as cellulitis, at the bottom of the eyelid extending to the cheekbone?

Antibiotic Treatment for Periorbital Cellulitis Extending to the Cheekbone

For an otherwise healthy adult with bacterial cellulitis extending from the lower eyelid to the cheekbone, initiate oral cephalexin 500 mg every 6 hours for 5 days, as beta-lactam monotherapy successfully treats 96% of typical nonpurulent cellulitis cases. 1

Critical Initial Assessment

Before prescribing antibiotics, you must immediately evaluate for orbital involvement versus simple periorbital (preseptal) cellulitis, as orbital cellulitis is a vision- and life-threatening emergency requiring IV antibiotics and urgent ophthalmology consultation 2:

• Warning signs of orbital cellulitis: Pain with eye movement, proptosis (bulging eye), restricted extraocular movements, decreased visual acuity, or afferent pupillary defect 2
• Imaging requirement: If any orbital signs are present, obtain emergent CT scan of orbits with contrast before initiating treatment 2
• Systemic toxicity indicators: Fever >38°C, hypotension, altered mental status, or severe pain out of proportion to examination findings mandate hospitalization and IV therapy 1

First-Line Oral Antibiotic Regimen

For uncomplicated periorbital cellulitis without orbital involvement or systemic toxicity:

• Cephalexin 500 mg orally every 6 hours (four times daily) for 5 days 1, 3
• Alternative beta-lactams include dicloxacin 250-500 mg every 6 hours or amoxicillin-clavulanate 875/125 mg twice daily 1
• Treatment duration: Exactly 5 days if clinical improvement occurs; extend only if symptoms have not improved within this timeframe 1

Rationale: Beta-hemolytic streptococci (especially Streptococcus pyogenes) and methicillin-sensitive Staphylococcus aureus cause the vast majority of typical cellulitis, and beta-lactam monotherapy achieves 96% success rates 1, 4

When to Add MRSA Coverage

Do NOT routinely add MRSA coverage for typical facial cellulitis. However, add MRSA-active antibiotics if any of these specific risk factors are present 1:

• Purulent drainage or exudate from the infection site
• Penetrating trauma or recent facial procedure
• Known MRSA colonization or previous MRSA infection
• Injection drug use
• Failure to respond to initial beta-lactam therapy after 48 hours

If MRSA coverage is needed:

• Clindamycin 300-450 mg orally every 6 hours provides single-agent coverage for both streptococci and MRSA 3
• Use clindamycin only if local MRSA clindamycin resistance rates are <10% 1
• Alternative: Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily PLUS a beta-lactam (never as monotherapy, as it lacks streptococcal coverage) 1

Penicillin/Cephalosporin Allergy Alternatives

For patients with documented penicillin or cephalosporin allergy:

• Clindamycin 300-450 mg orally every 6 hours for 5 days is the optimal choice, providing coverage for both streptococci and MRSA without requiring combination therapy 1, 3
• Clindamycin is FDA-approved for serious skin and soft tissue infections caused by susceptible streptococci and staphylococci 3
• Critical caveat: Cross-reactivity between penicillins and cephalosporins is only 2-4%, so cephalexin remains an option for most penicillin-allergic patients except those with immediate hypersensitivity reactions 1

Hospitalization and IV Therapy Indications

Admit for IV antibiotics if any of the following are present 1:

• Orbital involvement confirmed by examination or imaging
• Systemic inflammatory response syndrome (SIRS): fever, tachycardia >90 bpm, tachypnea >24 rpm
• Hypotension or altered mental status
• Severe immunocompromise or neutropenia
• Rapid progression despite oral antibiotics
• Inability to take oral medications

IV regimen for hospitalized patients:

• Vancomycin 15-20 mg/kg IV every 8-12 hours (first-line, A-I evidence) 1
• Alternative: Cefazolin 1-2 g IV every 8 hours if MRSA risk factors are absent 1
• For severe infection with systemic toxicity: Vancomycin PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours 1

Mandatory Reassessment and Follow-Up

• Reassess within 24-48 hours to verify clinical response, as treatment failure rates of 21% have been reported with some oral regimens 1
• Signs of improvement: Decreased warmth, reduced tenderness, stabilization or regression of erythema border
• Treatment failure indicators: Expanding erythema, increasing pain, new systemic symptoms, or development of orbital signs 1
• If no improvement after 48 hours on appropriate antibiotics, consider resistant organisms (MRSA), deeper infection (orbital cellulitis, abscess), or alternative diagnosis 1

Essential Adjunctive Measures

• Elevation: Keep head elevated, especially when sleeping, to promote gravitational drainage of periorbital edema 1
• Warm compresses: Apply to affected area to increase local blood flow
• Predisposing factors: Examine for and treat underlying conditions such as facial dermatitis, eczema, or chronic sinusitis that may have served as portal of entry 1, 2

Common Pitfalls to Avoid

• Do not reflexively add MRSA coverage for typical facial cellulitis without specific risk factors—this represents overtreatment and increases antibiotic resistance 1
• Do not extend treatment to 10-14 days based on tradition if clinical improvement occurs by day 5—this increases adverse effects without improving outcomes 1
• Do not delay ophthalmology consultation if any orbital signs develop, as orbital cellulitis can progress to cavernous sinus thrombosis, meningitis, or permanent vision loss 2
• Do not use doxycycline or trimethoprim-sulfamethoxazole as monotherapy for facial cellulitis, as their activity against beta-hemolytic streptococci is unreliable 1