What is the recommended treatment for orbital cellulitis?

Treatment of Orbital Cellulitis

For orbital cellulitis, initiate immediate IV antibiotics with nafcillin or cefazolin to cover Staphylococcus aureus and Streptococcus species, with hospitalization and daily monitoring until definite clinical improvement occurs. 1

Initial Assessment and Risk Stratification

When evaluating suspected orbital cellulitis, immediately assess for:

• Proptosis, impaired visual acuity, or painful/impaired extraocular movements - these mandate hospitalization and IV therapy 1
• Systemic signs of infection (fever, tachycardia, altered mental status) - require immediate admission 1
• Degree of eyelid closure - if >50% closed, hospitalize regardless of other factors 1
• CT scan of orbits with IV contrast is the most useful imaging to differentiate preseptal from postseptal involvement and identify complications 1

Antibiotic Selection Algorithm

For Moderate to Severe Orbital Cellulitis (Hospitalized Patients)

First-line IV therapy:

• Nafcillin (penicillinase-resistant penicillin) OR Cefazolin 1-2g IV every 8 hours 1, 2
• Alternative effective regimen: Ceftriaxone plus clindamycin 1

These agents target the two most common pathogens: Staphylococcus aureus and Streptococcus species 1

For severe penicillin allergy:

• Clindamycin or Vancomycin 1

For Mild Periorbital Cellulitis (Outpatient Candidates)

Only if eyelid <50% closed, no proptosis, no visual changes, and reliable follow-up:

• High-dose amoxicillin-clavulanate as first-line 1
• Oral ciprofloxacin plus clindamycin may be as effective as IV therapy based on bioavailability data 3

Critical caveat: Outpatient treatment requires mandatory reassessment within 24-48 hours - if no improvement or any progression, immediate hospitalization and IV therapy 1

MRSA Coverage Considerations

Add MRSA-active antibiotics when:

• Risk factors present (penetrating trauma, known MRSA colonization, injection drug use) 1
• Failure to respond to standard beta-lactam therapy within 48 hours 1

MRSA-active options:

• Vancomycin 15-20 mg/kg IV every 8-12 hours (first-line for hospitalized patients) 4
• Clindamycin (if local resistance <10%) 1
• Trimethoprim-sulfamethoxazole or Doxycycline (as alternatives) 1

Treatment Duration and Monitoring

• Standard duration: 5-7 days, extending only if infection has not improved 1
• Daily assessment is necessary for hospitalized patients to monitor response 1
• Repeat CT imaging if clinical suspicion of progression to intracranial complications 1

Surgical Intervention

Consult ophthalmology, otolaryngology, and infectious disease when:

• No improvement after 24-48 hours of appropriate IV antibiotics 1, 2
• Evidence of subperiosteal abscess with clinical deterioration 2
• Orbital complications or intracranial extension 1

Important note: CT evidence of subperiosteal abscess alone is NOT an absolute indication for drainage - most respond to medical management 2

Common Pitfalls to Avoid

• Delaying imaging in patients with proptosis, visual changes, or ophthalmoplegia - these require immediate CT 1
• Using penicillin G or ampicillin - these show 100% resistance in bacterial susceptibility testing for orbital cellulitis pathogens 5
• Inadequate follow-up for outpatient cases - failure to reassess within 24-48 hours can lead to vision-threatening complications 1
• Not considering MRSA coverage when standard therapy fails or risk factors are present 1
• Treating as simple preseptal cellulitis when true orbital involvement exists - this requires more aggressive management 1

Transition to Oral Therapy

Once definite clinical improvement occurs (typically after 3-7 days IV therapy):

• Amoxicillin-clavulanate for continued coverage 1, 6
• Clindamycin if MRSA coverage needed and local resistance low 1
• Complete total antibiotic course of 5-7 days from initiation 1