What is the recommended dose of doxycycline (Doxycycline) for a widespread Staphylococcus (Staph) infection on the legs and trunk?

Doxycycline Dosing for Widespread Staphylococcal Skin Infection

For a widespread staphylococcal infection involving the legs and trunk, doxycycline should be dosed at 100 mg orally twice daily for 5-10 days, based on clinical response. 1

Dosing Regimen

• Standard adult dose: 100 mg orally twice daily 1
• Duration: 5-10 days, individualized based on clinical response 1
• First-day loading: The FDA label recommends 200 mg on day 1 (100 mg every 12 hours), followed by 100 mg daily maintenance, though for more severe infections 100 mg every 12 hours is recommended 2

Clinical Context and Rationale

Doxycycline is an appropriate oral option for empirical coverage of community-acquired MRSA in outpatients with skin and soft tissue infections (SSTI). 1 The IDSA guidelines specifically list tetracyclines (doxycycline or minocycline) as A-II level recommendations for empirical CA-MRSA coverage in outpatient SSTI. 1

When to Use Doxycycline

• Purulent cellulitis (cellulitis with purulent drainage or exudate without drainable abscess) warrants empirical CA-MRSA coverage 1
• Extensive disease involving multiple sites qualifies for antibiotic therapy beyond simple incision and drainage 1
• Widespread infection on legs and trunk meets criteria for antibiotic treatment 1

Important Limitations

Doxycycline does NOT provide coverage for beta-hemolytic streptococci. 1 If you suspect both streptococcal and staphylococcal involvement (nonpurulent cellulitis with systemic toxicity), you must add a beta-lactam such as amoxicillin to the doxycycline regimen. 1

Efficacy Data

Retrospective cohort data demonstrates that tetracyclines are superior to beta-lactams for community-onset MRSA SSTI. 3 In a study of 282 MRSA SSTI episodes, patients receiving beta-lactams had nearly 4 times higher odds of treatment failure compared to those receiving doxycycline or minocycline (adjusted OR 3.94,95% CI 1.28-12.15). 3 Treatment failure occurred in only 10% of cases overall, with median time to failure of 3 days. 3

MRSA susceptibility to tetracyclines is typically excellent, with median susceptibility rates of 95% in community settings. 3

Pediatric Considerations

Tetracyclines should NOT be used in children under 8 years of age due to risk of permanent tooth discoloration. 1

For children ≥8 years:

• Weight <45 kg: 2 mg/kg/dose orally every 12 hours 1
• Weight ≥45 kg: Adult dose of 100 mg orally every 12 hours 1

Common Pitfalls

• Failing to add beta-lactam coverage when nonpurulent cellulitis is present—doxycycline alone misses streptococcal pathogens 1
• Using doxycycline for hospitalized patients with complicated SSTI—these patients require IV therapy with vancomycin, linezolid, or daptomycin 1
• Inadequate fluid intake—tetracyclines should be taken with adequate fluids to reduce esophageal irritation and ulceration risk 2
• Prescribing to children <8 years—this causes permanent dental staining 1

Administration Considerations

Doxycycline may be given with food or milk if gastric irritation occurs, as absorption is not significantly affected. 2 This distinguishes it from some other tetracyclines and improves tolerability.

No dose adjustment is needed for renal impairment at usual recommended doses. 2