What are the first-line antibiotic recommendations for preseptal cellulitis?

First-Line Antibiotic Recommendations for Preseptal Cellulitis

For preseptal cellulitis, the first-line oral antibiotic therapy is cephalexin 500 mg 3-4 times daily for 5-6 days, with alternative options including clindamycin and amoxicillin-clavulanate. 1

Antibiotic Regimens for Preseptal Cellulitis

First-Line Options:

• Cephalexin: 500 mg orally 3-4 times daily for 5-6 days 1

Alternative Options:

• Clindamycin: 300-450 mg orally three times daily for 5-6 days 1
• Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5-6 days 1, 2

MRSA Considerations

If risk factors for MRSA are present, consider broader antibiotic coverage:

• Clindamycin: 300-450 mg orally three times daily 1
• Trimethoprim-sulfamethoxazole (TMP-SMX): For MRSA coverage 1, 3

For severe infections with suspected MRSA that are not responding to oral therapy:

• Vancomycin: 15-20 mg/kg IV every 8-12 hours 1
• Linezolid with rifampin: Consider for cases that fail to respond to vancomycin 4

Special Populations

Pediatric Patients:

• Children weighing less than 100 pounds: Dose based on weight
  • Cephalexin: 25-45 mg/kg/day divided into 3-4 doses 1
  • Amoxicillin-clavulanate: 45 mg/kg/day divided every 12 hours for more severe infections 2

Patients with Renal Impairment:

• Adjust dosing for patients with impaired renal function:
  • For GFR <30 mL/min: Avoid 875 mg/125 mg amoxicillin-clavulanate 2
  • For GFR 10-30 mL/min: Use 500 mg/125 mg or 250 mg/125 mg every 12 hours 2

Clinical Pearls and Pitfalls

• Obtain cultures: When possible, obtain cultures from purulent material to guide antibiotic therapy 1
• Reassessment: Patients should be reassessed within 2-3 days and considered for antibiotic change if no improvement is seen after 72 hours 1
• Duration of therapy: Standard treatment duration for most bacterial skin infections is 5-6 days, but may be extended to 7-14 days for more severe cases 1
• Penicillin allergy: Patients with immediate hypersensitivity reactions to penicillin should avoid cephalosporins due to cross-reactivity concerns 1
• Children under 8: Should not receive doxycycline due to risk of dental staining 1, 5
• Pregnant patients: Should avoid doxycycline 1, 5

Common Pathogens

The most common pathogens causing preseptal cellulitis include:

• Staphylococcus aureus (including MRSA) 6, 7
• Streptococcus species (including Group A Streptococcus) 8
• Haemophilus influenzae (less common since Hib vaccination) 7

Treatment Failure

If no improvement is seen after 72 hours of initial therapy:

1. Consider changing antibiotics based on local resistance patterns
2. Re-evaluate for possible orbital involvement or abscess formation
3. Consider imaging studies (CT or MRI) to rule out complications
4. Consider broader spectrum antibiotics or combination therapy 1, 4

Remember that preseptal cellulitis can progress to orbital cellulitis or other serious complications if not treated appropriately, so prompt and effective antibiotic therapy is essential.