Antibiotic Treatment for Gram-Positive Cocci Infections

Introduction to Antibiotic Selection

The Infectious Diseases Society of America recommends daptomycin 10 mg/kg/dose IV once daily for complicated MRSA infections 1, 2
The Infectious Diseases Society of America recommends linezolid 600 mg IV every 12 hours for MRSA infections 1, 2
The Infectious Diseases Society of America recommends ceftaroline standard dosing IV for MRSA infections 1, 2
The Infectious Diseases Society of America recommends dalbavancin single or two-dose regimen IV for MRSA infections 1, 2
The Infectious Diseases Society of America recommends tedizolid 200 mg IV every 24 hours for MRSA infections 1, 2
The Infectious Diseases Society of America recommends tigecycline standard dosing IV for MRSA infections 1, 2

For necrotizing fasciitis with Group A Streptococci, the Infectious Diseases Society of America recommends combination therapy with clindamycin 600-900 mg IV every 8 hours PLUS penicillin 3
For polymicrobial necrotizing infections, the Infectious Diseases Society of America recommends a preferred regimen of ampicillin-sulbactam 1.5-3.0 g IV every 6-8 hours PLUS clindamycin 600-900 mg IV every 8 hours PLUS ciprofloxacin 400 mg IV every 12 hours 3
For Fournier's gangrene in stable patients, the Infectious Diseases Society of America recommends piperacillin/tazobactam 4.5 g IV every 6 hours PLUS clindamycin 600 mg IV every 6 hours 4
For Fournier's gangrene in unstable patients, the Infectious Diseases Society of America recommends one broad-spectrum agent (piperacillin/tazobactam 4.5 g every 6 hours, meropenem 1 g every 8 hours, OR imipenem/cilastatin 500 mg every 6 hours) PLUS one anti-MRSA agent (linezolid 600 mg every 12 hours, tedizolid 200 mg every 24 hours, vancomycin, teicoplanin, daptomycin 6-8 mg/kg daily, OR telavancin 10 mg/kg daily) PLUS clindamycin 600 mg every 6 hours 4

The Infectious Diseases Society of America notes that clindamycin resistance is now very common in MRSA, limiting its utility 1, 2
The Infectious Diseases Society of America notes that glycopeptide MIC creep, with rising vancomycin MICs, may affect efficacy even in "susceptible" isolates 1, 2
The Infectious Diseases Society of America recommends a standard duration of therapy of 7-14 days for most skin and soft tissue infections, individualized based on clinical response 1, 2
The Infectious Diseases Society of America recommends implementing IV-to-oral switch when clinical stability criteria are met (afebrile, improving inflammatory markers, tolerating oral intake) 1, 2
The Infectious Diseases Society of America recommends obtaining microbiological samples before starting antibiotics and de-escalating from broad-spectrum to targeted therapy based on susceptibility results and clinical improvement 4

The Infectious Diseases Society of America recommends vancomycin 40 mg/kg/day IV divided every 8-12 hours (up to 2 g daily) with target trough concentrations of 15-20 μg/mL in severe infections for methicillin-resistant S. aureus (MRSA) 5, 6
For methicillin-susceptible S. aureus (MSSA), the American College of Clinical Pharmacy suggests anti-staphylococcal penicillins (oxacillin or nafcillin) at 200 mg/kg/day IV divided every 4-6 hours (up to 12 g/day) 6
The Society for Healthcare Epidemiology of America recommends penicillin G 200,000-300,000 U/kg/day IV divided every 4 hours (up to 12-24 million U daily) for penicillin-susceptible streptococci 6
For ampicillin-susceptible enterococci, the Infectious Diseases Society of America suggests ampicillin 200-300 mg/kg/day IV divided every 4-6 hours (up to 12 g daily) plus gentamicin 6

In neutropenic patients with gram-positive infections, the Infectious Diseases Society of America recommends initial empiric therapy with an anti-pseudomonal β-lactam (cefepime, meropenem, imipenem-cilastatin, or piperacillin-tazobactam) 7, 5
Vancomycin should be added for specific indications, such as suspected catheter-related infections or known colonization with resistant gram-positive organisms, as recommended by the Infectious Diseases Society of America 8, 7

The Infectious Diseases Society of America suggests considering local resistance patterns when selecting empiric therapy 7, 5
Risk factors for resistant organisms include previous infection or colonization with resistant organisms, treatment in a hospital with high rates of resistance, and recent antibiotic exposure, as noted by the American College of Clinical Pharmacy 7, 6

The Infectious Diseases Society of America recommends monitoring vancomycin trough levels in patients with impaired renal function to avoid toxicity 7, 6
Therapy should be reassessed when culture and susceptibility results become available (typically within 48-72 hours), and de-escalation from broad-spectrum to targeted therapy should be considered based on susceptibility results, as suggested by the Society for Healthcare Epidemiology of America 6, 7, 6