Management of Gram-Positive Cocci in Pairs on Blood Cultures
For a patient with blood cultures positive for gram-positive cocci in pairs who is currently on cefepime and vancomycin, continue the current antibiotic regimen until final identification and susceptibility results are available, then de-escalate therapy based on those results. 1
Initial Assessment
- Obtain at least one additional set of blood cultures (two bottles) from peripheral sites to confirm the initial finding and rule out contamination 2, 1
- If a central venous catheter is present, collect blood cultures from each lumen of the catheter 2
- Monitor complete blood count, renal function, electrolytes, and hepatic enzymes to assess the patient's clinical status and potential organ dysfunction 2
- Evaluate for signs of severe sepsis or hemodynamic instability which would warrant continued broad-spectrum coverage 2
Current Antibiotic Regimen Assessment
- The current regimen of cefepime and vancomycin is appropriate for empiric coverage of gram-positive cocci in pairs pending identification 2, 1
- Cefepime provides excellent coverage against many strains of viridans streptococci and other gram-positive organisms 2
- Vancomycin is appropriate for empiric coverage of potentially resistant gram-positive organisms including MRSA and resistant pneumococci 2, 1
Diagnostic Considerations
- Gram-positive cocci in pairs commonly represent:
- Streptococcus pneumoniae
- Viridans group streptococci
- Enterococci
- Occasionally Staphylococcus aureus 1
- Consider rapid diagnostic testing if available to expedite identification 3
Next Steps Based on Organism Identification
If Streptococcus pneumoniae is identified:
- Once susceptibility results are available, de-escalate from vancomycin to appropriate β-lactam therapy if the isolate is susceptible 1
- For penicillin-susceptible isolates, narrow to penicillin or ampicillin 2
- For penicillin-resistant isolates, continue cefepime if susceptible 2
If Viridans streptococci are identified:
- Cefepime alone provides excellent coverage for most viridans streptococci 2
- Discontinue vancomycin once susceptibility is confirmed unless the patient has endocarditis 2
- For suspected endocarditis, obtain echocardiography and consider longer duration of therapy 2
If Enterococci are identified:
- Continue vancomycin for Enterococcus faecium pending susceptibility 1
- For Enterococcus faecalis, consider switching to ampicillin if susceptible 4
- For suspected endocarditis, add gentamicin for synergy 4
If Staphylococcus aureus is identified:
- Continue vancomycin for MRSA 1
- Consider switching to nafcillin/oxacillin for MSSA 1
- Obtain echocardiography to rule out endocarditis 2
Monitoring and Follow-up
- Monitor vancomycin trough levels if therapy continues beyond 72 hours, especially in patients with impaired renal function 1
- Reassess therapy when culture and susceptibility results become available (typically within 48-72 hours) 1
- Consider infectious disease consultation for complicated infections or if endocarditis is suspected 2
Common Pitfalls to Avoid
- Continuing vancomycin unnecessarily when cultures identify organisms susceptible to narrower-spectrum antibiotics 1
- Treating a single positive blood culture for coagulase-negative staphylococci without confirmation from a second culture 2
- Failing to investigate for endocarditis in patients with persistent bacteremia 2
- Discontinuing antibiotics prematurely before complete identification and susceptibility testing 1