From the Guidelines
Colistin is recommended as a treatment for Acinetobacter infections, particularly when the isolate is sensitive only to polymyxins, with a suggested dose of 5 mg/kg IV as a loading dose, followed by 2.5 mg/kg IV every 12 hours, adjusted for renal function 1.
Key Considerations
- The treatment of Acinetobacter infections with colistin should be guided by antimicrobial susceptibility testing to ensure the isolate is sensitive to colistin.
- Combination therapy with other antibiotics, such as carbapenems, may be considered, but the evidence for its benefit is limited, and it may not provide a significant advantage over monotherapy with colistin 1.
- Monitoring renal function is crucial, as nephrotoxicity is a significant side effect of colistin, occurring in 30-50% of patients.
- Inhaled colistin may be added for respiratory infections to achieve higher drug concentrations in the lungs while minimizing systemic toxicity.
Dosage and Administration
- The recommended dose of colistin is 5 mg/kg IV as a loading dose, followed by 2.5 mg/kg IV every 12 hours, adjusted for renal function 1.
- The dose should be adjusted based on creatinine clearance, with a recommended daily dose of 1.25-15 million units divided into 2-3 doses for adjunctive inhaled colistin.
Important Notes
- Colistin works by disrupting bacterial cell membranes, causing leakage of cellular contents and bacterial death.
- Neurotoxicity can also occur, manifesting as paresthesias, dizziness, or neuromuscular blockade.
- The treatment duration is usually 7-14 days, depending on the infection site and clinical response.
From the FDA Drug Label
INDICATIONS AND USAGE Colistimethate for Injection, USP is indicated for the treatment of acute or chronic infections due to sensitive strains of certain gram-negative bacilli. Colistimethate for Injection, USP has proven clinically effective in treatment of infections due to the following gram-negative organisms: Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa
The FDA drug label does not answer the question.
From the Research
Treatment of Acinetobacter Infections using Colistin
- Colistin is used as a salvage therapy for nosocomial infections caused by multidrug-resistant Acinetobacter baumannii 2.
- The combination of colistin and rifampicin has been shown to be effective and safe for the treatment of severe infections due to multidrug-resistant A. baumannii, with a clinical and microbiological response rate of 76% 3.
- Colistin can be used in combination with other antibacterial agents, such as meropenem, tigecycline, fosfomycin, fusidic acid, or sulbactam, to treat extensively drug-resistant Acinetobacter baumannii infections 4.
- However, colistin resistance has been reported, and the mechanism of resistance may involve the loss of lipopolysaccharide or the PmrAB two-component system 5.
- Combination therapy with colistin and other antibacterial agents may be the best antimicrobial strategy against colistin-resistant A. baumannii 5.
Efficacy and Safety of Colistin
- Colistin has been shown to be effective in treating nosocomial infections caused by multidrug-resistant A. baumannii, with a favorable clinical response rate of 76.9% 2.
- The safety profile of colistin is generally good, with nephrotoxicity being the most common adverse event, occurring in 10% of patients 3.
- However, the risk of nephrotoxicity may be higher when colistin is used in combination with other antibacterial agents 6.
Combination Therapy with Colistin
- Colistin can be used in combination with rifampicin, meropenem, tigecycline, fosfomycin, fusidic acid, or sulbactam to treat Acinetobacter baumannii infections 3, 4.
- The combination of colistin and rifampicin has been shown to be effective and safe for the treatment of severe infections due to multidrug-resistant A. baumannii 3.
- The combination of colistin and meropenem may be an appropriate option for treating extensively drug-resistant Acinetobacter baumannii infections, especially when the meropenem MIC is ≤32 mg/L 4.