From the Research
For multidrug-resistant (MDR) Acinetobacter infections, imipenem-EDTA is generally preferred over ceftazidime-avibactam due to its ability to overcome certain resistance mechanisms in Acinetobacter, as supported by the most recent study 1. Imipenem-EDTA typically combines imipenem (500mg IV every 6 hours) with EDTA as a beta-lactamase inhibitor that helps overcome certain resistance mechanisms in Acinetobacter. Ceftazidime-avibactam (2.5g IV every 8 hours), while effective against many gram-negative pathogens, has limited activity against MDR Acinetobacter because avibactam does not inhibit the metallo-beta-lactamases (MBLs) commonly produced by this organism. When treating MDR Acinetobacter, combination therapy is often necessary, potentially adding colistin (loading dose of 9 million units, then 4.5 million units IV every 12 hours, adjusted for renal function) or tigecycline. Some key points to consider when treating MDR Acinetobacter infections include:
- Treatment duration typically ranges from 7-14 days depending on infection site and clinical response.
- Susceptibility testing is crucial before initiating therapy as resistance patterns vary significantly between institutions.
- Monitoring for seizures with imipenem and renal function with both agents is essential, with dose adjustments required for patients with renal impairment. The most recent study 1 suggests that ceftazidime/avibactam may be more suitable than ceftazidime for polymyxin B based combination therapy against CR-A. baumannii, as it has a higher synergistic rate with polymyxin B, and the antibacterial activity of ceftazidime/avibactam is much higher than that of ceftazidime when tested in combination with polymyxin B. However, imipenem-EDTA remains the preferred treatment option due to its established efficacy and safety profile, as supported by earlier studies 2, 3, 4, 5.