What is the recommended management for preseptal cellulitis, including antibiotic selection, dosing, indications for hospital admission, and follow‑up for children and adults?

Preseptal Cellulitis Management

Antibiotic Selection

For preseptal cellulitis, initiate beta-lactam monotherapy with oral cephalexin 500 mg every 6 hours or dicloxacillin 250–500 mg every 6 hours for 5 days in adults, as this provides excellent coverage against the primary pathogens (Staphylococcus aureus and beta-hemolytic streptococci) with a 96% success rate. 1

Pediatric Antibiotic Selection

• Children: Cephalexin 25 mg/kg/day divided into four doses or amoxicillin-clavulanate 45 mg/kg/day divided twice daily for 5 days 1, 2
• Young children (<36 months) with concurrent upper respiratory symptoms or otitis: Add coverage for Haemophilus influenzae with amoxicillin-clavulanate 45 mg/kg/day, as these patients are at risk for bacteremia 3
• Pediatric IV therapy (if hospitalized): Vancomycin 15 mg/kg IV every 6 hours if MRSA risk factors present, or cefazolin 25–50 mg/kg/day divided every 8 hours for typical cases 1

Adult Alternative Regimens

• Penicillin allergy: Clindamycin 300–450 mg orally every 6 hours (only if local MRSA resistance <10%) 1, 4
• Severe penicillin allergy with cephalosporin contraindication: Levofloxacin 500 mg daily or moxifloxacin 400 mg daily 1

When to Add MRSA Coverage

Add MRSA-active antibiotics only when these specific risk factors are present 1, 5:

• Penetrating trauma or injection drug use
• Purulent drainage or exudate
• Known MRSA colonization or prior MRSA infection
• Failure to respond to beta-lactam therapy after 48–72 hours
• Systemic inflammatory response syndrome (fever >38°C, tachycardia, hypotension)

MRSA regimens:

• Outpatient: Clindamycin 300–450 mg every 6 hours (if resistance <10%) OR trimethoprim-sulfamethoxazole 1–2 double-strength tablets twice daily PLUS cephalexin 500 mg four times daily 1, 5
• Inpatient: Vancomycin 15–20 mg/kg IV every 8–12 hours 1, 5

Treatment Duration

Treat for exactly 5 days if clinical improvement occurs (reduced warmth, tenderness, and erythema); extend only if symptoms have not improved within this timeframe. 1 Traditional 7–14 day courses are no longer necessary for uncomplicated cases 1.

Indications for Hospital Admission

Admit patients with any of the following high-risk features 1, 5, 6:

• Age <6 months with moderate-to-severe disease
• Systemic toxicity: Fever with hypotension, altered mental status, or confusion
• Concern for orbital extension: Diplopia, ophthalmoplegia, proptosis, or pain with extraocular movements (these findings are never present in isolated preseptal cellulitis) 6, 7
• Rapidly progressive infection or severe pain out of proportion to examination
• Severe immunocompromise or neutropenia
• CRP >120 mg/L (suggests possible orbital involvement requiring imaging) 6
• Inability to take oral medications or lack of reliable follow-up

Inpatient IV Antibiotic Regimens

• Standard: Cefazolin 1–2 g IV every 8 hours (adults) or 25–50 mg/kg/day divided every 8 hours (children) 1
• MRSA coverage needed: Vancomycin 15–20 mg/kg IV every 8–12 hours (adults) or 15 mg/kg IV every 6 hours (children) 1, 5
• Severe infection with systemic toxicity: Vancomycin 15–20 mg/kg IV every 8–12 hours PLUS piperacillin-tazobactam 3.375–4.5 g IV every 6 hours 1, 5

Transition to oral therapy once clinical improvement is demonstrated (typically after 48–72 hours of IV treatment), then complete a total 5–7 day course 1, 2.

Diagnostic Imaging

Obtain urgent CT scan with contrast if any of the following are present 6, 7:

• Diplopia, ophthalmoplegia, or proptosis (suggests orbital cellulitis)
• Visual acuity changes or afferent pupillary defect
• Severe pain with eye movements
• CRP >120 mg/L
• Failure to improve after 48 hours of appropriate antibiotics

CT helps detect complications early, including subperiosteal abscess (most commonly medial), orbital abscess, or intracranial extension 6.

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. Document the extent of erythema, warmth, and swelling at each visit to track progression or improvement 1.

Signs of Treatment Failure Requiring Escalation

• Expanding erythema or worsening swelling after 48–72 hours
• Development of orbital signs: Proptosis, diplopia, ophthalmoplegia, or vision changes 6, 7
• Persistent fever beyond 48 hours of appropriate therapy
• Severe pain out of proportion to examination findings

If treatment failure occurs, switch to vancomycin 15–20 mg/kg IV every 8–12 hours and obtain CT imaging to rule out orbital extension or abscess formation 1, 6.

Adjunctive Measures

• Warm compresses to the affected area three times daily 1
• Elevation of the head of the bed to promote drainage 1
• Treat predisposing conditions: Sinusitis (present in 77.8% of orbital cellulitis cases but only 2% of preseptal cases), skin trauma, or insect bites 6, 3

Critical Pitfalls to Avoid

• Never assume preseptal cellulitis is benign in young children (<36 months) with concurrent upper respiratory symptoms—these patients require coverage for H. influenzae and are at risk for bacteremia 3
• Never delay CT imaging if any orbital signs are present, as complications (vision loss, brain abscess, cavernous sinus thrombosis, death) can develop rapidly 6, 7
• Never use doxycycline or trimethoprim-sulfamethoxazole as monotherapy for typical preseptal cellulitis, as they lack reliable streptococcal coverage 1, 5
• Never continue ineffective antibiotics beyond 48–72 hours—progression despite appropriate therapy indicates either resistant organisms or orbital extension requiring imaging and treatment escalation 1, 6