What is the first-line treatment for preseptal cellulitis?

First-Line Treatment for Preseptal Cellulitis

The first-line treatment for preseptal cellulitis is an oral antibiotic active against beta-hemolytic streptococci, with cephalexin 500mg four times daily for 5 days being the preferred option for mild to moderate cases. 1, 2

Pathogen Considerations

• Preseptal cellulitis is most commonly caused by beta-hemolytic streptococci, particularly Streptococcus pyogenes (Group A Streptococcus) 1
• Staphylococcus aureus is a less frequent cause but should be considered in cases with purulent drainage or following penetrating trauma 3, 1
• MRSA is an unusual cause of typical non-purulent cellulitis, with studies showing beta-lactam therapy is successful in 96% of cases 2

Treatment Algorithm

Mild to Moderate Preseptal Cellulitis (Outpatient)

• First-line oral therapy options include:
  • Cephalexin 500mg four times daily 1, 2
  • Amoxicillin or amoxicillin-clavulanate 1
  • Dicloxacillin 1
  • Penicillin 1
• Standard duration is 5 days, which is as effective as 10 days if clinical improvement is observed 3, 1, 2
• For patients with beta-lactam allergies, clindamycin is an appropriate alternative 1, 2

Severe Preseptal Cellulitis (Inpatient)

• First-line parenteral therapy options include:
  • Nafcillin or oxacillin 3, 1
  • Cefazolin 3, 1
  • For patients with life-threatening penicillin allergies: clindamycin or vancomycin 3, 1

Adjunctive Measures

• Elevation of the affected area to promote drainage of edema and inflammatory substances 1, 2
• Systemic corticosteroids (e.g., prednisone 40mg daily for 7 days) may be considered in non-diabetic adult patients to attenuate inflammation and hasten resolution 3, 1
• Address predisposing conditions such as sinusitis, which is present in over 50% of cases 4, 2

Indications for Hospitalization

• Systemic inflammatory response syndrome (SIRS) 1
• Altered mental status 1
• Hemodynamic instability 1
• Concern for deeper infection 1
• Poor adherence to therapy 1
• Failure of outpatient treatment 1
• Children with high C-reactive protein levels (>120 mg/L) which may indicate orbital involvement 5

Warning Signs of Complications

• Development of proptosis, impaired visual acuity, or painful/impaired extraocular mobility suggests progression to orbital cellulitis requiring immediate hospitalization 1, 5
• CT scan should be performed if orbital involvement is suspected 1, 5
• Fever is more common in orbital cellulitis (82.2%) compared to preseptal cellulitis (51.5%) 5

Common Pitfalls to Avoid

• Failing to distinguish between preseptal and orbital cellulitis, which have very different management approaches and potential outcomes 1, 5
• Unnecessarily prescribing MRSA coverage for typical non-purulent preseptal cellulitis 2
• Prolonging antibiotic therapy beyond 5 days in cases showing good clinical response 1, 2
• Overlooking predisposing factors such as sinusitis, which is present in a significant percentage of cases 4, 6