Management of Staphylococcus lugdunensis Bacteremia
Treat S. lugdunensis bacteremia with the same aggressive approach as S. aureus bacteremia, including mandatory echocardiography, source control, and prolonged antibiotic therapy (4-6 weeks for complicated cases), because this coagulase-negative staphylococcus causes endocarditis and metastatic infections with mortality rates comparable to S. aureus. 1
Why S. lugdunensis Demands Special Attention
Unlike other coagulase-negative staphylococci that are often dismissed as contaminants, S. lugdunensis behaves like S. aureus with aggressive virulence. The 2009 IDSA catheter-related infection guidelines explicitly state that "CRBSI due to Staphylococcus lugdunensis should be managed in a manner similar to CRBSI due to S. aureus" 1. This organism causes valve destruction, abscess formation, and has mortality rates of 30-37% in endocarditis cases—comparable to MRSA endocarditis 2.
Recent data confirms that even single positive blood cultures often represent true bacteremia rather than contamination, particularly when intravascular devices are present 3, 4. In one multicenter study, 97% of patients with S. lugdunensis in a single blood culture set fulfilled SIRS criteria, had an infectious focus on imaging, or had a second positive culture site 3.
Antibiotic Selection
First-Line Therapy
- For methicillin-susceptible isolates: Use cefazolin or an antistaphylococcal penicillin (nafcillin/oxacillin)
- For methicillin-resistant isolates: Use vancomycin (15-20 mg/kg IV q8-12h) or daptomycin (6 mg/kg IV daily, consider 8-10 mg/kg for complicated cases)
S. lugdunensis remains highly susceptible to most antibiotics, which is atypical for coagulase-negative staphylococci 5. The breakpoints are similar to S. aureus rather than other CNS 5. For aggressive infections like endocarditis or bone/joint infections, β-lactam agents are recommended when susceptible 5.
Do not routinely add gentamicin or rifampin to vancomycin for bacteremia or native valve endocarditis, as combination therapy does not improve outcomes and increases toxicity 6, 7. One case report described successful treatment with cefazolin plus rifampin for persistent bacteremia with endocarditis 8, but this is not standard practice.
Essential Investigations
Mandatory Workup
- Repeat blood cultures at 2-4 days after initial positive cultures to document clearance 6, 7
- Echocardiography for ALL patients: Transesophageal echocardiography (TEE) is preferred over transthoracic (TTE) because of superior sensitivity for vegetations and complications 7
- Clinical assessment for source identification and metastatic foci through history, physical exam, and symptom-directed imaging 6
- Source control evaluation: Remove infected intravascular devices promptly after establishing alternative access 9, 10
Timing Considerations
Perform TEE 5-7 days after bacteremia onset to minimize false-negative results 1. The high propensity for endocarditis and perivalvular extension with S. lugdunensis makes this timing critical 2.
Treatment Duration
Uncomplicated Bacteremia (ALL criteria must be met):
- Endocarditis excluded by TEE
- No implanted prostheses
- Follow-up blood cultures negative at 2-4 days
- Defervescence within 72 hours of effective therapy
- No metastatic infection sites
Duration: Minimum 2 weeks 6, 7
Complicated Bacteremia (any of the following):
- Persistent bacteremia beyond 72 hours
- Presence of prosthetic devices
- Metastatic infection foci
- Slow clinical response
- Undrainable infection foci
Duration: 4-6 weeks depending on extent of infection 6, 7, 10
Endocarditis:
Duration: 6 weeks of IV therapy 6, 7
The Surviving Sepsis Campaign guidelines note that "longer courses are appropriate in patients who have a slow clinical response, undrainable foci of infection, bacteremia with Staphylococcus aureus, some fungal and viral infections, or immunologic deficiencies" 9, 10—and S. lugdunensis should be managed similarly.
Source Control
Identify and eliminate the source within 12 hours when feasible 9, 10. Common sources include:
- Central venous catheters (most common at 17%) 3
- Arteriovenous fistulas for hemodialysis 11
- Other intravascular devices
- Skin and soft tissue infections
Remove infected intravascular devices promptly after establishing alternative access 9, 10, 1. For long-term catheters, removal is strongly recommended unless major contraindications exist (no alternative access, severe bleeding diathesis) 1.
Critical Pitfalls to Avoid
Do not dismiss as a contaminant: While single positive blood cultures may represent contamination in some cases, the presence of intravascular devices, SIRS criteria, or clinical signs of infection strongly predict true bacteremia 3, 4. When in doubt, treat as significant.
Do not use short courses: Unlike other coagulase-negative staphylococci that may resolve with catheter removal alone, S. lugdunensis requires full antibiotic courses 1.
Do not skip echocardiography: The rate of endocarditis is similar between S. lugdunensis and S. aureus bacteremia (approximately 12-16%) 12, 13.
Do not delay infectious disease consultation: Studies show that ID consultation improves diagnostic workup (more echocardiograms performed, more deep infections diagnosed) and reduces 90-day and 1-year mortality 14.
Role of Infectious Disease Consultation
Obtain ID consultation for all cases of S. lugdunensis bacteremia. A multicenter study demonstrated that bedside ID consultation was associated with:
- More frequent echocardiography (OR 4.00-16.0) 14
- More deep infections diagnosed (OR 7.44-9.56) 14
- Lower 90-day mortality (OR 0.11) and 1-year mortality (OR 0.22) 14
The complexity of managing this organism—distinguishing true bacteremia from contamination, determining appropriate treatment duration, and identifying metastatic complications—makes specialist input valuable for optimizing outcomes.