From the Guidelines
Colistin (Polymyxin E) has antimicrobial coverage against gram-negative bacteria, particularly multidrug-resistant organisms, including Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae. The antimicrobial spectrum of colistin includes most Enterobacteriaceae, including many carbapenem-resistant strains 1. However, it has notable gaps in coverage, including all gram-positive bacteria, anaerobes, Proteus species, Serratia marcescens, Morganella morganii, and Providencia species, which have modifications in their lipopolysaccharide structure that prevent colistin binding 1. Some key points to consider when using colistin include:
- The optimal dose of colistin is 9 MU of colistin methanesulfonate (CMS) initially followed by 4.5 MU CMS twice a day as the maintenance dose, as supported by international consensus guidelines and expert panel discussions 1.
- Renal function should be monitored during colistin treatment, and therapeutic drug monitoring is recommended when available to optimize dosing and minimize toxicity 1.
- Combination therapy with other antibiotics may be employed to prevent resistance development and potentially achieve synergistic effects, but the use of colistin-based combination therapy is controversial and should be considered on a case-by-case basis 1. It's essential to weigh the benefits and risks of colistin treatment, considering its potential for nephrotoxicity and neurotoxicity, and to carefully monitor patients for signs of adverse effects 1.
From the Research
Antimicrobial Coverage of Colistin (Polymyxin E)
- Colistin, also known as Polymyxin E, has been used to treat infections caused by multidrug-resistant Gram-negative bacteria, including Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae 2, 3.
- The antimicrobial coverage of Colistin includes:
- Acinetobacter baumannii: Colistin has been shown to be effective against this pathogen, with a clinical response rate of 66.7% in one study 2.
- Pseudomonas aeruginosa: Colistin has been used to treat infections caused by this pathogen, with a reported clinical response rate of 62.0% in another study 3.
- Klebsiella pneumoniae: Colistin has been used to treat infections caused by this pathogen, although the clinical response rate is not as well established as for other pathogens 2, 3.
- The use of Colistin as a salvage therapy for multidrug-resistant and extremely drug-resistant Gram-negative bacterial infections has been evaluated, with reported clinical cure rates ranging from 50.0% to 62.0% 3.
- Colistin can be administered intravenously, by inhalation, or via the intraventricular/intrathecal route, with the choice of administration route depending on the site of infection and the patient's condition 4, 5.