Antibiotic Treatment for Acinetobacter baumannii

First-Line Treatment

The American College of Critical Care Medicine recommends carbapenems (imipenem, meropenem, or doripenem) as the first-line treatment for carbapenem-susceptible A. baumannii in areas with low carbapenem resistance rates 1, 2
The Infectious Diseases Society of America suggests that carbapenems should not be used as monotherapy for severe infections in areas with high resistance rates (>25% carbapenem resistance) 2

The European Society of Clinical Microbiology and Infectious Diseases recommends imipenem dosing at 0.5–1 g every 6 hours (extended infusion not possible due to drug instability) 3
The International Society for Antimicrobial Chemotherapy suggests meropenem dosing at 2 g every 8 hours (high doses associated with seizure risk) 3

The American College of Critical Care Medicine recommends ampicillin-sulbactam as the preferred treatment for CRAB with sulbactam MIC ≤4 mg/L, due to its superior safety profile and comparable efficacy to polymyxins 2, 3
The Infectious Diseases Society of America suggests sulbactam dosing at 9–12 g/day in 3 daily doses, administered as 4-hour infusions (3 g sulbactam every 8 hours) 2, 3
Clinical studies demonstrate comparable outcomes to imipenem for severe infections 3
Sulbactam has lower nephrotoxicity compared to colistin (15.3% vs 33%) 2, 3
Microbiologic cure rates at day 7 are significantly higher with sulbactam than colistin 3

The European Society of Clinical Microbiology and Infectious Diseases recommends colistin as a treatment option for CRAB showing resistance to all beta-lactams and sulbactam 1, 5
The International Society for Antimicrobial Chemotherapy suggests colistin dosing with a loading dose of 6–9 million IU, followed by maintenance doses of 4.5 million IU every 12 hours in critically ill patients with creatinine clearance >50 mL/min 1, 5
Polymyxin B is an alternative to colistin, with a loading dose of 2–2.5 mg/kg and maintenance doses of 1.5–3 mg/kg/day in 2 doses 1, 5
Polymyxin B is associated with less nephrotoxicity than colistin 1

The American College of Critical Care Medicine recommends against using tigecycline as monotherapy for bacteremia or primary bloodstream infections due to suboptimal serum concentrations 5, 1
The Infectious Diseases Society of America suggests that tigecycline may be considered for approved indications only (complicated intra-abdominal infections, complicated skin/soft tissue infections) with secondary bacteremia 1, 5
High-dose tigecycline regimens (200 mg loading, then 100 mg every 12 hours) may be used for severe infections as part of combination therapy, though not FDA-approved 1, 3

The European Society of Clinical Microbiology and Infectious Diseases recommends combination therapy with two in vitro active agents for severe CRAB infections (septic shock, severe sepsis) 4, 6
Recommended combinations include colistin + high-dose carbapenem, colistin + sulbactam + tigecycline, and sulbactam or polymyxin + second agent (tigecycline, rifampicin, or fosfomycin) 6, 7

The American College of Critical Care Medicine recommends maintaining antimicrobial therapy for 2 weeks for severe infections (VAP, bacteremia with severe sepsis/septic shock) 7, 4
Shorter durations may be acceptable for less severe infections 7

The Infectious Diseases Society of America suggests considering nebulized colistin as adjunctive therapy for MDR A. baumannii pneumonia/VAP 4
The European Society of Clinical Microbiology and Infectious Diseases recommends against using tigecycline monotherapy for pneumonia/VAP due to poor lung penetration 1, 5
For urinary tract infections, ampicillin-sulbactam 3 g sulbactam every 8 hours is recommended for sulbactam-susceptible isolates, and colistin (6-9 million IU loading, then 9 million IU/day) for sulbactam-resistant isolates 6

The American College of Critical Care Medicine recommends monitoring renal function closely in all patients receiving colistin (nephrotoxicity occurs in up to 33% of patients) 4, 8