First-Line Treatment for Preseptal Cellulitis
For mild to moderate preseptal cellulitis, initiate oral therapy with penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, or cephalexin for 5 days, targeting the primary pathogen Streptococcus pyogenes (Group A Streptococcus). 1
Pathogen-Directed Therapy
The causative organism drives antibiotic selection:
Beta-hemolytic streptococci, particularly Streptococcus pyogenes, cause the majority of preseptal cellulitis cases. 1 This is confirmed by clinical data showing S. pyogenes as the predominant pathogen in both pediatric and adult populations. 2, 3
Staphylococcus aureus represents a secondary but important pathogen, particularly in cases with trauma or purulent features. 1, 4
MRSA is uncommon in typical preseptal cellulitis and does not require routine empiric coverage. 1
Oral Antibiotic Options for Outpatient Management
First-line oral agents (choose one):
- Cephalexin - provides excellent coverage against both streptococci and methicillin-sensitive S. aureus 1
- Dicloxacillin - penicillinase-resistant option with strong anti-staphylococcal activity 1
- Amoxicillin-clavulanate - broader coverage including beta-lactamase producing organisms, particularly useful if recent amoxicillin use or traumatic wounds 1
- Penicillin or amoxicillin - appropriate when streptococcal infection is most likely 1
Treatment Duration
Treat for 5 days if clinical improvement is evident - this duration is equally effective as 10-day courses for uncomplicated cases. 1
Extend therapy only if infection has not improved by day 5. 1
Reassess at 48-72 hours to confirm treatment response. 1
Parenteral Therapy for Severe Cases
Indications for hospitalization and IV antibiotics include: 1
- Systemic inflammatory response syndrome (SIRS)
- Altered mental status or hemodynamic instability
- Concern for orbital extension (proptosis, impaired visual acuity, painful/impaired extraocular movements)
- Failure of outpatient treatment
- Poor adherence anticipated
IV antibiotic options (choose one):
- Nafcillin or oxacillin 1
- Cefazolin 1
- Clindamycin or vancomycin (if MRSA risk factors present or penicillin allergy) 1
Special Populations and Considerations
For penicillin-allergic patients:
- Clindamycin monotherapy provides coverage for both streptococci and S. aureus, with 99.5% of S. pyogenes strains remaining susceptible. 5
When to add MRSA coverage (use clindamycin alone OR trimethoprim-sulfamethoxazole plus a beta-lactam): 1, 5
- Penetrating trauma
- Purulent drainage present
- Evidence of MRSA infection elsewhere
- Known MRSA nasal colonization
- IV drug use
Adjunctive Measures
Elevate the affected area to promote drainage of edema and inflammatory substances. 1
Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients to hasten resolution, though evidence is limited. 1 Corticosteroids have shown benefit in orbital cellulitis management and may be extrapolated cautiously. 3, 6
Critical Warning Signs Requiring Immediate Action
Hospitalize immediately and obtain CT imaging if any of the following develop: 1
- Proptosis (forward displacement of the globe)
- Impaired visual acuity
- Impaired or painful extraocular movements
- Diplopia or ophthalmoplegia 3
These signs indicate potential progression to orbital cellulitis, which has vastly different management and potential for vision-threatening complications. 1, 3
Common Pitfalls to Avoid
Failing to distinguish preseptal from orbital cellulitis - this is the most critical error, as orbital cellulitis requires immediate hospitalization, IV antibiotics, and potential surgical intervention. 1 Key differentiating features include age (orbital cellulitis more common in older children, mean age 7.5 years vs 3.9 years), presence of fever (82% vs 52%), preexisting sinusitis (78% vs 2%), and markedly elevated CRP (>120 mg/L suggests orbital involvement). 3
Unnecessarily prolonging antibiotics beyond 5 days when good clinical response is evident. 1
Routinely covering MRSA without specific risk factors - this represents inappropriate broad-spectrum use. 1
Using doxycycline as monotherapy - it lacks reliable streptococcal coverage and should not be used for preseptal cellulitis. 7