Treatment of Carbapenem-Resistant Acinetobacter baumannii (CRAB)

Recommended Treatment Regimens

The American College of Microbiology recommends using colistin with a carbapenem (meropenem 2g IV q8h or imipenem 500mg IV q6h) as combination therapy, with adjunctive inhaled colistin for at least 7 days for CRAB pneumonia 1
The Infectious Diseases Society of America suggests that colistin-carbapenem combination therapy is the primary regimen for CRAB pneumonia, with a colistin loading dose of 5 mg CBA/kg, followed by 2.5 mg CBA × (1.5 × CrCl + 30) IV q12h, and a carbapenem (meropenem or imipenem) at specific doses 1
The European Society of Clinical Microbiology and Infectious Diseases recommends sulbactam monotherapy (6-9 g/day IV in 3-4 divided doses) as an alternative regimen for CRAB pneumonia, but only if the MIC is ≤4 mg/L 1, 2

The American College of Microbiology recommends using combination therapy (two active agents) for severe infections with septic shock, ventilator-associated pneumonia, bacteremia with severe sepsis, clinical failures on monotherapy, and isolates with MIC at the upper limit of susceptibility 1, 3, 4
The Infectious Diseases Society of America suggests that combination therapy prevents the emergence of colistin resistance during treatment and achieves higher microbiological eradication rates and reduced mortality in XDR-AB bloodstream infections 3, 2

The American College of Microbiology recommends monitoring renal function closely, with a nephrotoxicity risk of 33-39% with colistin therapy, and adjusting the colistin maintenance dose based on CrCl using a specific formula 5, 4
The European Society of Clinical Microbiology and Infectious Diseases suggests monitoring for hepatotoxicity if using tigecycline, which is associated with increased hepatotoxicity 4

The American College of Microbiology recommends a treatment duration of at least 7 days for pneumonia, typically 10-14 days for HAP/VAP, and 10-14 days for bloodstream infections 1, 6
The Infectious Diseases Society of America suggests maintaining treatment for 2 weeks in cases of severe sepsis or septic shock 7, 4

The Infectious Diseases Society of America recommends sulbactam-based therapy (9-12 g/day in 3-4 divided doses) as the preferred first-line treatment for patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections and impaired renal function, when the MIC is ≤4 mg/L, due to its comparable efficacy to colistin with significantly lower nephrotoxicity risk 8, 9
Sulbactam demonstrates comparable clinical cure rates to colistin but with markedly lower nephrotoxicity (15.3% vs 33%) 8
In patients with existing renal dysfunction, sulbactam is preferable to preserve remaining kidney function and avoid colistin-associated nephrotoxicity 9
The 4-hour infusion of sulbactam optimizes pharmacokinetic/pharmacodynamic properties and may allow treatment of isolates with MIC up to 8 mg/L 8

The European Society of Clinical Microbiology and Infectious Diseases recommends not skipping the colistin loading dose in patients with renal impairment, as subtherapeutic levels persist for 2-3 days without loading, increasing mortality risk 8
The Clinical and Laboratory Standards Institute recommends not using automated susceptibility testing for sulbactam, but instead using Etest with MIC ≤4 mg/L as the susceptibility breakpoint 8, 9