Treatment of Carbapenem-Resistant Acinetobacter baumannii Infections

First-Line Treatment Options

For CRAB susceptible to sulbactam, ampicillin-sulbactam is the preferred treatment, especially for hospital-acquired/ventilator-associated pneumonia (HAP/VAP) 1
For CRAB resistant to sulbactam, a polymyxin (colistin) should be used if the isolate is susceptible in vitro 1, 2

Ampicillin-sulbactam: Administer as a 4-hour infusion of 3g sulbactam every 8 hours (9-12g/day total) for isolates with MIC ≤4 mg/L 1, 2
Colistin: Dosing should be weight-based and adjusted for renal function according to institutional protocols 1

Combination therapy is recommended for severe CRAB infections to improve clinical outcomes and prevent resistance 1
Colistin plus glycopeptides (vancomycin) is discouraged due to increased nephrotoxicity 1, 3

For CRAB with meropenem MIC <8 mg/L, high-dose extended-infusion carbapenem as part of combination therapy may be considered 1
Duration of therapy should be individualized but generally maintained for 2 weeks in severe infections such as VAP or bacteremia 4

Monitor renal function in patients receiving colistin, as nephrotoxicity occurs in up to 33% of patients 2
Monitor for emergence of resistance during therapy, particularly with colistin, as heteroresistance has been reported 5

Obtain cultures and susceptibility testing before initiating therapy 6
Start empiric therapy based on local resistance patterns and patient risk factors 2
For confirmed CRAB infection:
- If susceptible to sulbactam: Use ampicillin-sulbactam (9-12g/day) 1, 2
- If resistant to sulbactam: Use colistin (with appropriate weight-based dosing) 1
- For severe infections: Consider combination therapy with two active agents 1
Continue treatment for approximately 2 weeks for severe infections 4