What is the treatment for Acinetobacter baumannii infection?

From the Guidelines

Acinetobacter baumannii infections should be treated with a combination of antibiotics, with intravenous colistin (loading dose of 5 mg CBA/kg, then 2.5 mg CBA every 12 hours) or polymyxin B, often combined with a carbapenem such as meropenem (2 grams every 8 hours as extended infusions), as the recommended first-line treatment. This approach is based on the most recent guidelines from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) 1 and recommendations from the Journal of Microbiology, Immunology and Infection 1. The choice of antibiotic treatment for Acinetobacter baumannii infections depends on the susceptibility of the strain, with ampicillin-sulbactam being a suitable option for strains susceptible to sulbactam 1.

For patients with severe and high-risk Acinetobacter baumannii infections, combination therapy including two in vitro active antibiotics among the available antibiotics (polymyxin, aminoglycoside, tigecycline, sulbactam combinations) is suggested 1. The treatment duration is typically 7-14 days depending on the infection site and severity, with a minimum of 7 days for pneumonia and 10-14 days for bloodstream infections 1.

It is essential to note that susceptibility testing is crucial as resistance patterns vary widely, and source control through drainage of abscesses or removal of infected devices is essential when applicable 1. Alternative options for susceptible strains include ampicillin-sulbactam, minocycline, or newer agents like cefiderocol, although the use of cefiderocol is not recommended for the treatment of infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) 1.

Key considerations in the treatment of Acinetobacter baumannii infections include:

• The use of colistin or polymyxin B as part of the empirical treatment in patients with severe infections and high probability of CRAB 1
• The importance of adjusting the maintenance dose of colistin according to creatinine clearance 1
• The potential use of polymyxin B as a suitable alternative to colistin, with a recommended dose of 1.5-3 mg/kg/day 1

From the FDA Drug Label

1.1 Lower Respiratory Tract Infections Imipenem and Cilastatin for Injection, USP (I.V.) for intravenous use is indicated for the treatment of lower respiratory tract infections caused by susceptible strains of Staphylococcus aureus (penicillinase-producing isolates), Acinetobacter species, Enterobacter species, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella species, Serratia marcescens. 1.7 Skin and Skin Structure Infections Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of skin and skin structure infections caused by susceptible strains of Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing isolates), Staphylococcus epidermidis, Acinetobacter species, Citrobacter species, Enterobacter species, Escherichia coli, Klebsiella species, Morganella morganii, Proteus vulgaris, Providencia rettgeri, Pseudomonas aeruginosa, Serratia species, Peptococcus species, Peptostreptococcus species, Bacteroides species including B. fragilis, Fusobacterium species.

Treatment of Acinetobacter banimani

• Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of infections caused by susceptible strains of Acinetobacter species.
• The dosage recommendations for Imipenem and Cilastatin for Injection (I.V.) are as follows:
  • 500 mg every 6 hours
  • 1,000 mg every 8 hours
  • 1,000 mg every 6 hours for infections caused by bacterial species with intermediate susceptibility 2

From the Research

Treatment Options for Acinetobacter baumannii Infections

• The treatment of Acinetobacter baumannii infections is challenging due to its resistance to multiple antimicrobial agents, including carbapenems and polymyxins 3.
• Effective antibiotics against A. baumannii infections include carbapenems, polymyxins E and B, sulbactam, piperacillin/tazobactam, tigecycline, and aminoglycosides 3.
• However, the optimal treatment for A. baumannii nosocomial infections, especially for multidrug-resistant (MDR) strains, has not been established 3.

Carbapenem-Resistant A. baumannii (CRAB) Infections

• The preferred treatment for CRAB infections has not been defined, and traditional agents with retained in vitro activity are limited by suboptimal pharmacokinetic characteristics, emergence of resistance, and/or toxicity 4.
• Combination therapy, including meropenem, polymyxin B, and ampicillin/sulbactam, is advocated for critically ill patients infected with CRAB 4.
• Newer agents, such as cefiderocol and eravacycline, demonstrate potent in vitro activity against CRAB, but clinical data do not yet support widespread use 4.

Emerging Treatment Options

• Several anti-infectives that target CRAB are in later-stage clinical trials, including cefiderocol, sulbactam-durlobactam, and other novel drugs such as BV-100, cefepime-zidebactam, zosurabalpin, and OMN6 5.
• These newer molecules may provide alternative treatment options for CRAB infections, but further clinical trials are needed to establish their efficacy and safety 5.

Treatment of CAPT-Resistant A. baumannii

• CAPT-resistant A. baumannii, which is co-resistant to carbapenems, aminoglycosides, polymyxins, and tigecycline, poses a significant treatment challenge 6.
• Treatment options for CAPT-resistant A. baumannii are limited, but synergistic combinations of older agents, such as polymyxin- or fosfomycin-based combinations, may represent a last resort option 6.
• Further study is needed to establish the efficacy and safety of these treatment options for CAPT-resistant A. baumannii 6.