What is the treatment for Acinetobacter (A.) baumannii in Intensive Care Unit (ICU) settings?

From the Guidelines

Treatment for Acinetobacter (A.) baumannii in Intensive Care Unit (ICU) settings is primarily based on polymyxins, such as colistin or polymyxin B, due to their in vitro activity against this pathogen.

Key Considerations

• Colistin is suggested as part of the empirical treatment in patients with severe infections and high probability of CR A. baumannii, with a recommended loading dose of 6–9 million IU and subsequently high, extended-interval maintenance doses (4.5 million IU/12 h) in critically ill patients and patients with severe sepsis/septic shock with creatinine clearance above 50 mL/min 1.
• Polymyxin B may be a suitable alternative to colistin, associated with less side effects, with a recommended dose of 1.5–3 mg/kg/day; a loading dose of 2–2.5 mg/kg is suggested 1.
• Ampicillin-sulbactam has shown advantage over polymyxins for CRAB in some studies, particularly in terms of mortality and clinical response, although the evidence is of low certainty 1.

Treatment Approaches

• Monotherapy vs. Combination Therapy: The use of monotherapy or combination therapy does not significantly impact clinical outcome, although some studies suggest that combination therapy may be associated with higher rates of microbiological eradication and clinical cure 1.
• Dosing and Administration: The maintenance dose of colistin should be individually adjusted according to creatinine clearance, and dose adjustment is not necessary for patients on continuous renal replacement therapy when using polymyxin B 1.
• Resistance and Susceptibility: The selection of empirical antimicrobial therapy should be based on local susceptibility patterns and the presence of risk factors for A. baumannii infection 1.

From the Research

Treatment Options for Acinetobacter baumannii in ICU Settings

• The treatment of Acinetobacter baumannii infections in ICU settings is challenging due to its high resistance to multiple antimicrobial agents 2, 3.
• Carbapenems may not be considered the treatment of choice in areas with high rates of carbapenem-resistant A. baumannii 2.
• Polymyxins, such as colistin, are often used to treat A. baumannii infections, with colistin being the most widely used in clinical practice 2.
• The recommended dosage of colistin is a loading dose of 9 million IU, followed by high, extended-interval maintenance doses (4.5 million IU/12 h) 2.
• Combination therapy, such as colistin and tigecycline, may increase the rates of microbiological eradication, but its effectiveness in reducing clinical outcomes is uncertain 2, 4.

Predictors of Multi-Drug Resistance

• Previous septic shock, previous adult respiratory distress syndrome (ARDS), number of previous antibiotics, previous aminoglycoside use, and reoperation are risk factors for multi-resistance in A. baumannii infections 5.
• Patients with previous septic shock and reoperation are at higher risk of developing multi-resistance, and colistin may be the only appropriate treatment option for these patients 5.

Infection Control Measures

• Strict infection control measures, including antimicrobial stewardship programs, can significantly reduce the incidence of nosocomial A. baumannii infections in ICU settings 6.
• The implementation of infection control bundles can lead to a significant reduction in the relative incidence of A. baumannii infections, with a relative risk reduction of 35% 6.