What is the recommended treatment for soft tissue cellulitis?

Recommended Treatment for Soft Tissue Cellulitis

The first-line treatment for soft tissue cellulitis is cephalexin 500 mg orally 3-4 times daily for 5-6 days, with alternative options including clindamycin 300-450 mg orally three times daily or amoxicillin-clavulanate 875/125 mg twice daily for patients with penicillin allergies. 1

Antibiotic Selection Algorithm

First-line Treatment:

• Cephalexin 500 mg orally 3-4 times daily for 5-6 days 1
  • Targets the most common pathogens (Streptococcus and Staphylococcus aureus)
  • Recent evidence suggests high-dose cephalexin (1000 mg four times daily) may result in fewer treatment failures compared to standard dosing, though with slightly more minor adverse effects 2

Alternative Options (for penicillin allergies or first-line failure):

• Clindamycin 300-450 mg orally three times daily for 5-6 days 1

  • Effective against both streptococci and staphylococci
  • Good option for penicillin-allergic patients

• Amoxicillin-clavulanate 875/125 mg twice daily orally for 5-6 days 1

  • Provides broader coverage including some gram-negative organisms
  • Consider when mixed infection is suspected

Special Considerations

MRSA Coverage:

Consider adding MRSA coverage for high-risk patients 1:

• Prior MRSA infections
• Injection drug use
• Recent hospitalization
• Athletes
• Prisoners
• Military recruits
• Residents of long-term care facilities

MRSA coverage options:

• TMP-SMX 1-2 double-strength tablets twice daily 1
  • Caution: Less effective against streptococci
• Doxycycline 100 mg twice daily 1
  • Not recommended for children under 8 years
• Linezolid 600 mg twice daily (for severe cases) 1
  • Expensive with risk of myelosuppression with prolonged use

Severe Infections Requiring IV Therapy:

• Cefazolin 1-2g IV every 8 hours (with or without metronidazole 500mg IV/oral every 8 hours for suspected anaerobic involvement) 1
• Piperacillin-tazobactam 3.375g IV every 6 hours (for complicated skin infections) 3
  • Particularly useful for diabetic foot infections or when broader coverage is needed

Treatment Duration and Assessment

• Standard duration: 5-7 days 1

• Extended duration may be needed for:

  • Elderly patients
  • Patients with diabetes
  • Patients with bacteremia
  • Infections not improved within initial treatment period

• Critical assessment point: 72 hours after starting therapy 1

  • If no improvement is seen, consider:
    1. Alternative antibiotic regimen
    2. Possible abscess requiring drainage
    3. Alternative diagnosis

Hospitalization Criteria

Consider inpatient treatment if 1:

• Concern for deeper or necrotizing infection
• Poor adherence to therapy expected
• Severely immunocompromised patient
• Outpatient treatment is failing
• Systemic symptoms (high fever, hypotension)

Common Pitfalls to Avoid

1. Inadequate MRSA coverage in high-risk patients 1

   • Particularly important in injection drug users

2. Using TMP-SMX alone for streptococcal infections 1

   • Poor activity against streptococci, which are common causes of cellulitis

3. Prescribing fluoroquinolones to children under 18 years 1

   • Contraindicated due to risk of tendon damage

4. Not adjusting therapy when clinical improvement is not seen within 72 hours 1

   • Failure to improve should prompt reevaluation

5. Overlooking potential uncommon pathogens in treatment-resistant cases 4

   • Consider culture and sensitivity testing for non-responding infections

Prevention Strategies

• Maintain good hand hygiene practices 1
• Avoid trauma to skin
• Keep skin clean and dry
• Promptly treat minor skin breaks
• Identify and treat predisposing conditions:
  • Edema
  • Obesity
  • Eczema
  • Venous insufficiency
  • Toe web abnormalities

The evidence strongly supports using "simple" antibiotics like cephalexin for uncomplicated soft tissue infections, with clinical response rates exceeding 95% 5. This approach is both cost-effective and clinically appropriate, as most cellulitis cases are caused by susceptible strains of Streptococcus and Staphylococcus aureus 6.