Best Treatment for Gram-Negative Bacteremia

Initial Empiric Treatment

The Infectious Diseases Society of America recommends combination therapy with two antimicrobial agents of different classes with gram-negative activity as initial empiric therapy for gram-negative bacteremia, followed by de-escalation to a single appropriate antibiotic once culture and susceptibility results are available 1
For empiric coverage, broad-spectrum agents with activity against Pseudomonas aeruginosa are recommended, as infections caused by gram-negative bacilli including P. aeruginosa have been associated with the highest infection-associated mortality 2
Recommended empiric regimens include a carbapenem (meropenem, imipenem, or doripenem) plus an aminoglycoside 3, 1
An antipseudomonal cephalosporin plus an aminoglycoside is also a recommended empiric regimen 2, 4
Piperacillin-tazobactam plus an aminoglycoside is another recommended empiric regimen 2, 5

Optimizing pharmacokinetic/pharmacodynamic parameters is crucial to ensure adequate serum bactericidal activity 4
Extended infusion (e.g., 3-hour infusion for meropenem) is recommended for carbapenems to improve efficacy 3
Therapeutic drug monitoring (TDM) is recommended for aminoglycosides to optimize dosing and minimize toxicity 6

De-escalation to a single appropriate antibiotic is recommended based on culture and susceptibility results 1
For carbapenem-resistant gram-negative bacilli (CRGNB), polymyxin (colistin) combination therapy is recommended over monotherapy 3
Ceftazidime-avibactam is recommended for susceptible isolates of CRGNB 7
Fosfomycin-containing combinations are recommended for Klebsiella pneumoniae carbapenemase (KPC) producers 8, 6

For persistent bacteremia or severe sepsis, therapy should be extended beyond 7-14 days 1
In patients with long-term catheters and persistent bacteremia, device removal is recommended and evaluation for endovascular or metastatic infection is necessary 1

For gram-negative catheter-related bloodstream infections (CRBSI), removal of short-term catheters is recommended 1
For long-term catheters, device removal is recommended for persistent bacteremia despite appropriate antibiotic therapy 1
Procalcitonin monitoring can be used to guide antimicrobial discontinuation in complicated cases 5

Monotherapy for suspected or proven Pseudomonas aeruginosa sepsis should be avoided due to the risk of rapid resistance development 4
Extended-spectrum β-lactamase (ESBL) producing organisms may appear susceptible to cephalosporins in vitro but can lead to treatment failure 7
Combining nephrotoxic drugs with polymyxins should be avoided due to the increased risk of renal injury 3
In vitro synergy testing results may not always translate to clinical benefits in the treatment of severe CRGNB infections 3