From the Guidelines
For Acinetobacter infections, imipenem/cilastatin is generally preferred over Zavicefta (ceftazidime/avibactam) due to its broader activity against this pathogen. Imipenem/cilastatin is typically administered at 500 mg to 1 g intravenously every 6-8 hours, with dosage adjustments needed for patients with renal impairment 1. Treatment duration usually ranges from 7-14 days depending on infection severity and site. Zavicefta has limited activity against Acinetobacter species, as avibactam does not inhibit the OXA-type carbapenemases commonly produced by Acinetobacter baumannii. In contrast, imipenem often retains activity against many Acinetobacter strains, though resistance rates are increasing globally.
Key Considerations
- Imipenem/cilastatin is the preferred treatment for Acinetobacter infections due to its broader activity against this pathogen
- Zavicefta has limited activity against Acinetobacter species
- Antimicrobial susceptibility testing is crucial before initiating therapy, as resistance patterns vary significantly by region and institution
- Treatment should be tailored based on culture results, infection site, and patient factors such as renal function and drug allergies
Treatment Approach
- Imipenem/cilastatin is typically administered at 500 mg to 1 g intravenously every 6-8 hours
- Dosage adjustments are needed for patients with renal impairment
- Treatment duration usually ranges from 7-14 days depending on infection severity and site
- For highly resistant Acinetobacter infections, combination therapy may be necessary, potentially including colistin, tigecycline, or high-dose ampicillin-sulbactam 1.
From the Research
Treatment Options for Acinetobacter Infections
- Zavicefta (ceftazidime/avibactam) and imipenem/cilastatin are two treatment options for Acinetobacter infections.
- According to a study published in 2010 2, carbapenems, including imipenem, are the mainstay of treatment for Acinetobacter baumannii infections.
- However, the study also notes that carbapenem-resistant Acinetobacter strains have increasingly been reported worldwide in recent years.
Efficacy of Ceftazidime/Avibactam
- A study published in 2019 3 investigated the in-vitro effectiveness of ceftazidime/avibactam alone or in combination with antibiotics against multidrug-resistant Acinetobacter baumannii isolates.
- The study found that ceftazidime/avibactam showed synergistic activities with colistin, tobramycin, and tigecycline against MDR A. baumannii isolates.
- Another study published in 2023 4 compared ceftazidime-avibactam-based therapy with polymyxin-based combination therapy for carbapenem-resistant Enterobacteriaceae and found that ceftazidime-avibactam-based therapy was associated with lower mortality rates.
Efficacy of Imipenem/Cilastatin
- A study published in 2021 5 reviewed the pharmacology, pharmacokinetics, pharmacodynamics, antimicrobial activity, efficacy, safety, and current regulatory status of imipenem/cilastatin/relebactam.
- The study found that imipenem/cilastatin/relebactam is active in vitro against a wide range of pathogens, including multidrug-resistant Pseudomonas aeruginosa and carbapenem-resistant Enterobacterales.
- However, the study also notes that the addition of relebactam does not restore the activity of imipenem against metallo-β-lactamase-producing Enterobacterales and carbapenem-resistant Acinetobacter baumannii.
Comparison of Zavicefta and Imipenem/Cilastatin
- There is limited direct comparison between Zavicefta and imipenem/cilastatin for the treatment of Acinetobacter infections.
- However, based on the available studies, ceftazidime/avibactam may be a viable option for the treatment of multidrug-resistant Acinetobacter baumannii infections, especially when used in combination with other antibiotics 3, 4.
- Imipenem/cilastatin/relebactam may also be effective against certain strains of Acinetobacter, but its efficacy against carbapenem-resistant strains is limited 5.