Gram-Positive Cocci in Pairs: Identification and Treatment
The most likely organism is Streptococcus species (including Streptococcus pyogenes or Streptococcus agalactiae) or Enterococcus species, and empiric therapy should be vancomycin, linezolid, or daptomycin pending culture identification and susceptibility testing.
Organism Identification
Gram-positive cocci in pairs visualized on wound culture Gram stain most commonly represent:
- Streptococcal species (including beta-hemolytic streptococci)
- Enterococcal species (Enterococcus faecalis or E. faecium)
- Less commonly: Staphylococcus aureus (though typically appears in clusters rather than pairs)
The Verigene assay demonstrates 89.7% concordance with culture for Gram-positive cocci in pairs and/or chains, confirming these organisms as the primary differential 1. In European surveillance of skin and soft tissue infections, beta-hemolytic streptococci accounted for 10.5% and enterococci for 9.3% of isolates 2.
Recommended Antimicrobial Therapy
Empiric Treatment (Before Susceptibility Results)
For severe wound infections, initiate vancomycin or alternative agents with robust gram-positive activity 3:
- Vancomycin: 30-60 mg/kg/day IV in 2-4 divided doses (target trough 15-20 µg/mL for severe infections)
- Linezolid: 600 mg IV/PO every 12 hours (100% oral bioavailability; covers VRE and MRSA)
- Daptomycin: 4-6 mg/kg/day IV (covers VRE; note potential cross-resistance with vancomycin-nonsusceptible strains)
- Ceftaroline: Alternative agent with gram-positive activity
These recommendations come from the 2014 IDSA guidelines for skin and soft tissue infections 3, which provide strong evidence (high quality) for empiric gram-positive coverage in wound infections.
Rationale for Broad Empiric Coverage
The choice of vancomycin or alternatives is critical because:
- Resistance patterns are evolving: Vancomycin-resistant enterococci (VRE) rates increased from 1.5% in 2003 to 11.0% in 2008 in European centers 2
- Gram-positive cocci increasingly include resistant organisms: 22.5% MRSA rate and 5.1% VRE rate overall in skin infections 2
- Daptomycin and linezolid maintain excellent activity: All monitored isolates were susceptible to daptomycin, with only one E. faecium isolate non-susceptible to linezolid 2
Targeted Therapy (After Culture Results)
Once organism identification and susceptibilities are available:
- For susceptible streptococci: De-escalate to penicillin G or ampicillin
- For susceptible enterococci: Ampicillin (for E. faecalis) or continue vancomycin/linezolid/daptomycin (for E. faecium or VRE)
- For resistant organisms: Continue vancomycin, linezolid, or daptomycin based on susceptibility patterns
Critical Considerations
Obtain Blood Cultures
Blood cultures should be obtained in addition to wound cultures, as skin lesions may harbor resistant microbes requiring aggressive evaluation 3.
Healthcare-Associated vs. Community-Acquired
- Healthcare-associated infections show higher rates of multidrug-resistant organisms (100% vs 50%, p=0.006) 4
- Patients on long-term quinolone prophylaxis have increased MDR bacteria (67% vs 24%, p=0.013) 4
Avoid Common Pitfalls
- Do not use first-generation cephalosporins for empiric therapy—they miss enterococci and have inadequate coverage for resistant streptococci
- Do not delay empiric broad-spectrum therapy while awaiting culture results in severe infections
- Do not assume beta-lactams will be effective—resistance is increasingly common in both community and healthcare settings 5
Duration and Monitoring
Treatment duration is typically 2 weeks after clinical resolution, though this may be extended based on infection severity and patient response. Monitor vancomycin troughs to maintain therapeutic levels (15-20 µg/mL) in severe infections 3.