How many days of Intravenous (IV) antibiotic therapy is recommended for bacteremia with a positive blood culture for Enterococcus or a Gram-negative organism?

Duration of IV Antibiotic Therapy for Bacteremia with Enterococcus or Gram-Negative Organisms

For uncomplicated bacteremia with Enterococcus or gram-negative organisms, a 7-14 day course of intravenous antibiotic therapy is recommended, with 10-14 days being the most appropriate duration for most cases. 1

Treatment Duration Based on Organism Type

Enterococcus Species

• Duration: 7-14 days of IV antibiotic therapy for uncomplicated enterococcal bacteremia 1
• Antibiotic selection:
  • Ampicillin for ampicillin-susceptible enterococci
  • Vancomycin for ampicillin-resistant strains
  • Linezolid or daptomycin for ampicillin- and vancomycin-resistant enterococci 1

Gram-Negative Organisms

• Duration: 10-14 days of IV antibiotic therapy for uncomplicated gram-negative bacteremia 1
• Antibiotic selection:
  • Based on susceptibility testing
  • Consider empiric coverage with drugs active against Pseudomonas aeruginosa in neutropenic patients 1

Factors That May Modify Treatment Duration

Factors Requiring Longer Treatment (4-6 weeks)

• Evidence of endocarditis
• Septic thrombosis
• Osteomyelitis
• Persistent bacteremia after catheter removal
• Underlying valvular heart disease 1

Factors Allowing Shorter Treatment

• Recent evidence suggests that 7 days of therapy may be sufficient for uncomplicated gram-negative bacteremia in clinically stable patients 2, 3
• Early switch to oral antibiotics (within 4 days) may be appropriate for uncomplicated gram-negative bacteremia in clinically stable patients 4

Catheter Management Considerations

Catheter Removal Recommendations

• Short-term catheters: Remove infected catheters 1
• Long-term catheters: Remove if there is:
  • Insertion site or pocket infection
  • Suppurative thrombophlebitis
  • Sepsis
  • Endocarditis
  • Persistent bacteremia
  • Metastatic infection 1

If Catheter Retention is Necessary

• For tunneled catheters or implantable devices that cannot be removed:
  • Extend antibiotic therapy to 14 days
  • Add antibiotic lock therapy to systemic antibiotics 1
  • Monitor with follow-up blood cultures
  • Remove catheter if bacteremia persists >72 hours after starting appropriate therapy 1

Clinical Monitoring During Treatment

• Assess for resolution of fever and clinical symptoms
• Obtain follow-up blood cultures to document clearance of bacteremia
• For enterococcal bacteremia, consider transesophageal echocardiography (TEE) if:
  • Signs/symptoms suggest endocarditis
  • Bacteremia or fever persists >72 hours despite appropriate therapy
  • Radiographic evidence of septic pulmonary emboli
  • Presence of prosthetic valve or other endovascular foreign bodies 1

Common Pitfalls to Avoid

• Premature discontinuation of antibiotics before adequate treatment duration, especially with deep-seated infections
• Failure to remove infected catheters when indicated, which can lead to persistent bacteremia and complications
• Inadequate assessment for metastatic foci of infection that may require longer treatment
• Overtreatment with prolonged courses when shorter durations would be sufficient for uncomplicated cases

Recent evidence from randomized controlled trials suggests that shorter courses (7 days) may be as effective as longer courses (14 days) for uncomplicated gram-negative bacteremia in patients who achieve clinical stability 2, 3, but most established guidelines still recommend 10-14 days of therapy for most cases of bacteremia with these organisms 1.