What are the recommended antibiotics for preseptal cellulitis?

Recommended Antibiotics for Preseptal Cellulitis

For mild preseptal cellulitis with less than 50% eyelid closure, treat as an outpatient with high-dose amoxicillin-clavulanate (Augmentin 875/125 mg twice daily in adults) for 5 days, providing comprehensive coverage against streptococci, staphylococci, and anaerobes. 1

Initial Assessment and Severity Stratification

• Measure eyelid closure percentage: If less than 50% closed, outpatient management is appropriate; if greater than 50% or any orbital signs present, immediate hospitalization is required. 1

• Screen for orbital involvement: The presence of proptosis, impaired visual acuity, painful or impaired extraocular movements, or ophthalmoplegia indicates progression to orbital cellulitis requiring immediate IV antibiotics and hospitalization. 1, 2

• Check inflammatory markers: C-reactive protein >120 mg/L strongly suggests orbital rather than preseptal cellulitis and warrants imaging and admission. 2

First-Line Antibiotic Selection

Outpatient Oral Therapy (Mild Cases)

• High-dose amoxicillin-clavulanate is the preferred first-line agent because it provides single-agent coverage for the polymicrobial flora typically involved: streptococci, staphylococci (including MSSA), and anaerobes. 1

• Alternative oral agents for penicillin-allergic patients include cephalexin 500 mg four times daily, dicloxacillin, or clindamycin 300-450 mg every 6 hours. 1

• Treatment duration is 5 days if clinical improvement occurs, extending only if symptoms have not improved within this timeframe. 3, 1

Inpatient IV Therapy (Severe Cases or Orbital Involvement)

• For hospitalized patients requiring IV therapy, the most commonly used regimens based on clinical experience include clindamycin (600 mg IV every 8 hours in adults) combined with ceftriaxone (1-2 g IV daily). 4, 2

• Alternative IV regimens include cefotaxime plus fosfomycin, or sulbactam-ampicillin, which have demonstrated safety and efficacy in pediatric preseptal and orbital cellulitis. 5, 6

MRSA Coverage: When and How

• MRSA coverage is generally unnecessary for typical preseptal cellulitis, as beta-lactam monotherapy succeeds in 96% of cases. 1

• Add MRSA-active antibiotics only when specific risk factors are present:

  • Penetrating trauma or history of injection drug use 1
  • Purulent drainage from the affected area 1
  • Evidence of MRSA infection elsewhere or known MRSA colonization 1
  • Failure of initial beta-lactam therapy after 24-48 hours 1

• For MRSA coverage when needed:

  • Oral option: Clindamycin 300-450 mg every 6 hours (covers both streptococci and MRSA) 1
  • IV option: Vancomycin 15-20 mg/kg every 8-12 hours 1, 4
  • Alternative for vancomycin failure: Linezolid plus rifampin has been reported effective in MRSA preseptal cellulitis resistant to vancomycin. 7

Mandatory Follow-Up and Escalation Criteria

• Daily follow-up is mandatory for outpatients until definite improvement is documented, typically within 24-48 hours. 1

• Escalate to IV antibiotics and hospitalization if:

  • No improvement within 24-48 hours of oral therapy 1
  • Progression of infection or development of orbital signs 1
  • Systemic toxicity, fever with altered mental status, or immunocompromise 1

Common Pitfalls to Avoid

• Do not reflexively add MRSA coverage to all preseptal cellulitis cases, as this represents overtreatment in the absence of specific risk factors. 1

• Do not use doxycycline or trimethoprim-sulfamethoxazole as monotherapy for preseptal cellulitis, as their activity against beta-hemolytic streptococci is unreliable. 3

• Do not delay imaging (CT scan) if orbital involvement is suspected, as early detection of complications like subperiosteal abscess changes management significantly. 2

• Do not continue ineffective antibiotics beyond 48 hours without reassessing for complications, resistant organisms, or misdiagnosis. 3

Special Populations

• Immunocompromised patients (malignancy, severe immunodeficiency) require a lower threshold for hospitalization and broader antibiotic coverage due to higher risk of complications including streptococcal toxic shock syndrome. 1

• Pediatric dosing for amoxicillin-clavulanate should be weight-based (45 mg/kg/dose of amoxicillin component twice daily), with the same 5-day duration if improvement occurs. 1