What is the recommended treatment for Staphylococcus lugdunensis infection in an adult with skin or soft‑tissue infection without prosthetic material?

Treatment of Staphylococcus lugdunensis Skin and Soft Tissue Infection

Treat Staphylococcus lugdunensis skin and soft tissue infections with the same aggressive approach as methicillin-susceptible Staphylococcus aureus (MSSA), using beta-lactam antibiotics as first-line therapy.

Key Clinical Principle

While the provided guidelines focus on MRSA treatment 1, 2, 1, 2, S. lugdunensis is a unique coagulase-negative staphylococcus that behaves clinically like S. aureus rather than typical skin flora. Recent evidence demonstrates that S. lugdunensis causes significant infections with comparable morbidity to S. aureus, including similar rates of infective endocarditis and metastatic complications 3, 4.

Treatment Algorithm

For Simple Cutaneous Abscesses:

• Primary treatment: Incision and drainage 1, 2, 1
• Add antibiotics if:
  • Multiple sites of infection
  • Rapid progression with surrounding cellulitis
  • Systemic signs (fever, tachycardia)
  • Immunosuppression or comorbidities
  • Difficult drainage location (face, hand, genitalia)
  • Failed drainage alone 1, 2, 1

Antibiotic Selection:

Outpatient oral therapy (5-10 days):

• First-line: Cephalexin 500 mg every 6 hours OR dicloxacillin 500 mg every 6 hours
• Alternatives: Clindamycin 300-450 mg every 8 hours (if local resistance <10%) 2
• Penicillin allergy: Trimethoprim-sulfamethoxazole 1-2 DS tablets twice daily OR doxycycline 100 mg twice daily 1

Hospitalized patients with complicated SSTI (7-14 days):

• IV options: Cefazolin 1-2 g every 8 hours OR nafcillin/oxacillin 2 g every 6 hours 5
• If MRSA coverage needed empirically: Vancomycin 15 mg/kg every 12 hours until cultures confirm S. lugdunensis 2, 1

Critical Distinctions from Typical CoNS:

S. lugdunensis is NOT a contaminant when isolated from clinical specimens 6, 7, 3. All isolates demonstrate methicillin susceptibility similar to MSSA, with resistance patterns showing:

• 100% susceptibility to vancomycin and linezolid 8
• High susceptibility to fluoroquinolones and TMP-SMX 8, 6
• Occasional beta-lactamase production (treat as MSSA) 7

Common Pitfalls to Avoid:

1. Do not dismiss as contamination: Unlike other coagulase-negative staphylococci, S. lugdunensis isolated from wounds or abscesses represents true infection requiring treatment 7, 3

2. Do not undertreat: This organism causes destructive infections comparable to S. aureus, including endocarditis in 5-14% of bacteremic cases 3, 4

3. Watch for recurrence: Patients on biologic therapies (anti-TNF agents) show higher recurrence rates and may need longer treatment courses 9

4. Surgical debridement is essential: For post-operative infections, aggressive surgical management combined with antibiotics achieves 96% cure rates 10

Special Populations:

Post-surgical infections: Require mean of 2 surgical procedures plus antibiotics; levofloxacin-rifampin combination shows good results in orthopedic infections 10

Older adults: Patients >65 years appear more susceptible to significant S. lugdunensis SSTI 6

Cancer patients: SSTI most common presentation (50%), typically following prior surgery or invasive procedures at the affected site 8

The clinical course and mortality of S. lugdunensis infections mirror S. aureus rather than typical coagulase-negative staphylococci, warranting the same level of clinical vigilance and aggressive management 3, 4.