Treatment of Oxacillin-Resistant, Beta-Lactamase Positive Staphylococcus lugdunensis Bacteremia
Vancomycin is the recommended first-line treatment for oxacillin-resistant Staphylococcus lugdunensis bacteremia, administered intravenously for a minimum of 6 weeks. 1
Antibiotic Selection
- Vancomycin is the drug of choice for methicillin/oxacillin-resistant staphylococcal bacteremia, including S. lugdunensis 1
- Treatment should be administered intravenously at a dosage of 30-60 mg/kg/day divided into 2-4 doses (typically 15 mg/kg every 6 hours) 1
- Daptomycin (6-10 mg/kg/dose IV daily) may be a reasonable alternative to vancomycin, particularly in cases with poor response to vancomycin therapy 1
- Addition of gentamicin or rifampin to vancomycin is not recommended for uncomplicated bacteremia 1
Duration of Therapy
- Minimum 6 weeks of therapy is recommended for S. lugdunensis bacteremia due to its virulence profile similar to S. aureus 1
- For complicated bacteremia (e.g., with metastatic foci of infection, endocarditis, or persistent bacteremia), at least 6 weeks of therapy is required 1
- Shorter courses (2 weeks) may be considered only for uncomplicated right-sided endocarditis, but this approach should not be applied to left-sided infections 1
Monitoring and Management
- Blood cultures should be repeated to document clearance of bacteremia 2
- Echocardiography (preferably transesophageal) should be performed to rule out endocarditis, as S. lugdunensis has a propensity for endocardial involvement similar to S. aureus 1
- Infectious diseases consultation is strongly recommended for management of S. lugdunensis bacteremia 1
- Patients with S. lugdunensis bacteremia should be cared for in a medical facility with cardiothoracic surgery capabilities due to the risk of endocarditis 1
Special Considerations
- S. lugdunensis, though a coagulase-negative staphylococcus, behaves more like S. aureus in terms of virulence and should be treated accordingly 3, 2
- While most S. lugdunensis isolates are typically susceptible to oxacillin (methicillin), resistance can occur through acquisition of the mecA gene and SCCmec elements 4, 3
- Beta-lactamase production, as in this case, further limits treatment options 3, 5
- Vancomycin MIC should be monitored, as higher MICs (≥1.5 mg/L) have been associated with increased mortality in MRSA infections 1
Treatment Algorithm
- Initiate vancomycin IV (15 mg/kg every 6 hours) immediately 1
- Obtain infectious diseases consultation 1
- Perform echocardiography to rule out endocarditis 1
- Monitor vancomycin trough levels (target 15-20 μg/mL for serious infections) 1
- Continue therapy for minimum 6 weeks 1
- Consider alternative agents (daptomycin) if clinical response is inadequate 1
- Follow blood cultures to document clearance of bacteremia 2
Common Pitfalls to Avoid
- Do not underestimate the virulence of S. lugdunensis despite it being a coagulase-negative staphylococcus; it should be treated as aggressively as S. aureus 3, 2
- Do not use cephalosporins despite in vitro susceptibility results, as cross-resistance exists with methicillin-resistant staphylococci 1
- Do not shorten therapy duration without confirming uncomplicated infection and complete clearance of bacteremia 1
- Do not fail to evaluate for metastatic foci of infection, particularly endocarditis 1