Management of Pseudomonas Bacteremia

Initial Empiric Therapy

The Infectious Diseases Society of America recommends initiating combination therapy with an antipseudomonal β-lactam PLUS either an aminoglycoside or fluoroquinolone until susceptibility results are available for patients with Pseudomonas bacteremia 1, 2
Combination therapy significantly improves the likelihood that at least one active agent is included in the initial regimen, which directly impacts mortality in bacteremia, with mortality being higher when initial therapy is inappropriate during the first 48 hours 1, 5, 6

The American College of Clinical Pharmacy recommends de-escalating to monotherapy with the most appropriate single agent based on susceptibility testing at 48-72 hours, once susceptibility results are available and the patient shows clinical improvement 1, 5, 6
De-escalation criteria include culture and susceptibility results available, patient clinically improving, organism susceptible to at least one agent, and no evidence of septic shock or critical illness 1, 5, 6

The Society of Critical Care Medicine recommends maintaining or escalating combination therapy for poor clinical response at 48-72 hours, multidrug-resistant Pseudomonas confirmed on susceptibility testing, persistent bacteremia on repeat blood cultures, or septic shock or hemodynamic instability 1, 2, 5, 6
Options for difficult-to-treat resistant Pseudomonas include ceftolozane/tazobactam, ceftazidime/avibactam, imipenem/cilastatin/relebactam, cefiderocol, and colistin-based therapy 2, 3

The Infectious Diseases Society of America recommends a standard duration of 10-14 days for Pseudomonas bacteremia, which is longer than the 7-10 days recommended for other infections due to the propensity for relapse and resistance development with Pseudomonas 2, 3, 5, 6

Never assume broad-spectrum equals antipseudomonal, as ceftriaxone, cefazolin, ampicillin/sulbactam, and ertapenem have no activity against Pseudomonas despite being broad-spectrum agents 2, 3
Never underdose, as standard doses may be inadequate for Pseudomonas infections, and never de-escalate prematurely without documented clinical improvement and susceptibility results 1, 2, 4, 5, 6

Obtain repeat blood cultures at 48-72 hours to document clearance of bacteremia, and monitor for clinical improvement, including resolution of fever, hemodynamic stability, and decreasing inflammatory markers 1, 5, 6
Perform therapeutic drug monitoring for aminoglycosides, targeting tobramycin peak 25-35 mg/mL, trough <1 mg/mL, and consider weekly susceptibility testing if prolonged therapy is required 2, 4