Vancomycin for Gram-Positive Cocci in Chains
Vancomycin is appropriate and recommended for empirical treatment of gram-positive cocci in chains on blood cultures until final identification and susceptibility results are available. 1, 2
Why Vancomycin is Appropriate
Gram-positive cocci in chains most commonly represent streptococcal species (including viridans streptococci, Streptococcus pneumoniae, and Streptococcus pyogenes) or enterococci, and vancomycin provides essential coverage for potentially resistant organisms in this group. 1, 2
Key Coverage Considerations
Vancomycin covers penicillin-resistant and cephalosporin-resistant Streptococcus pneumoniae, which can appear as cocci in chains and may be life-threatening if inadequately treated. 3, 4
Enterococci, particularly Enterococcus faecium, require vancomycin coverage as they are often ampicillin-resistant and can present as gram-positive cocci in chains. 1, 2
Viridans streptococci, while typically susceptible to beta-lactams, can occasionally be resistant or tolerant to penicillin, and mortality may be higher in patients not initially treated with vancomycin, particularly in neutropenic patients. 5
When Vancomycin Should Be Added
The Hospital Infection Control Practices Advisory Committee (HICPAC) and Infectious Diseases Society of America establish that vancomycin is appropriate for:
Treatment of serious infections caused by beta-lactam-resistant gram-positive microorganisms. 5
Treatment of infections caused by gram-positive microorganisms in patients with serious beta-lactam allergies. 5
Empirical therapy when gram-positive cocci are visualized on blood culture before final identification, especially in patients with hemodynamic instability, severe sepsis, or clinically suspected serious catheter-related infections. 1, 2
Optimal Empirical Regimen
Combination therapy with vancomycin plus an anti-pseudomonal beta-lactam (such as cefepime, piperacillin-tazobactam, or a carbapenem) is recommended for empirical coverage until organism identification is complete. 1, 2
Cefepime provides excellent activity against many streptococcal species including viridans group streptococci and S. pneumoniae, complementing vancomycin's coverage. 2
This combination ensures comprehensive coverage for both susceptible and resistant gram-positive organisms while also providing gram-negative coverage if needed. 1
Critical De-escalation Strategy
Plan for antibiotic de-escalation within 48-72 hours when identification and susceptibility results become available. 1, 2
If Streptococcus pneumoniae is identified and susceptible to beta-lactams, discontinue vancomycin and narrow to appropriate beta-lactam monotherapy. 1, 2
If viridans streptococci are identified, cefepime alone typically provides excellent coverage and vancomycin can be discontinued unless endocarditis is suspected. 2
If Enterococcus faecium is identified, continue vancomycin and consider adding an aminoglycoside if endocarditis is present. 2
Dosing and Monitoring
Vancomycin should be dosed at 15-20 mg/kg every 8-12 hours (typically 30-60 mg/kg/day in divided doses) to ensure adequate coverage for serious gram-positive infections. 1
Target trough concentrations of 15-20 mcg/mL are recommended for severe infections. 1, 6
Monitor vancomycin trough levels if therapy continues beyond 72 hours, particularly in patients with renal impairment, to avoid nephrotoxicity. 1, 2
Common Pitfalls to Avoid
Do not continue vancomycin unnecessarily when cultures identify organisms susceptible to narrower-spectrum antibiotics, as this promotes vancomycin resistance. 5, 1
Do not treat a single positive blood culture for coagulase-negative staphylococci without confirmation from a second culture, as this likely represents contamination rather than true infection. 5
Do not delay appropriate gram-positive coverage in a febrile patient with gram-positive cocci on blood culture, as this can lead to increased mortality, especially with virulent organisms like viridans streptococci in neutropenic patients. 5, 1
Obtain at least one additional set of blood cultures from peripheral sites to confirm the finding and rule out contamination. 1, 7