Colistin for Resistant Infections

Why does the CDC's pandemic analysis matter for colistin treatment?

The CDC's COVID-19 and antimicrobial resistance overview describes a historical setback: hospital-onset resistant infections and deaths each increased by at least 15% across seven pathogens between 2019 and 2020. Hospitals faced longer admissions, greater use of invasive devices and disrupted infection prevention. These figures describe the pandemic's first year; they are not newly measured October 2026 infection rates. [CDC overview](https://www.cdc.gov/antimicrobial-resistance/data-research/threats/covid-19.html)

That context makes the limitations of rescue antibiotics especially relevant. Colistin belongs to the polymyxin family and damages the outer membrane of certain gram-negative bacteria. It has been used when resistance leaves few alternatives, but its ability to injure the kidneys complicates treatment. International consensus guidance describes a narrow therapeutic window: achieving adequate antibacterial exposure while limiting toxicity can be difficult. [Polymyxin consensus guidance](https://pmc.ncbi.nlm.nih.gov/articles/PMC7437259/)

Does adding meropenem to colistin improve survival?

Published in NEJM Evidence in 2023, OVERCOME compared colistin plus meropenem with colistin plus placebo for pneumonia or bloodstream infections caused by specified resistant gram-negative bacteria. Researchers randomized 464 participants; 423 qualified for the main efficacy analysis. Mortality at 28 days was 43% with colistin alone and 37% with combination treatment, but the difference was not statistically significant. [OVERCOME trial](https://pubmed.ncbi.nlm.nih.gov/37538951/)

Most infections involved Acinetobacter baumannii, limiting conclusions about other organisms. The findings do not establish that every antibiotic combination is ineffective, or that colistin alone is the preferred treatment. They show that laboratory evidence of drugs working together does not necessarily translate into better patient outcomes. [Trial findings and limitations](https://pmc.ncbi.nlm.nih.gov/articles/PMC10398788/)

When is colistin still used, and how are kidney risks managed?

The Infectious Diseases Society of America's July 2026 guidance lists colistin as an alternative for uncomplicated urinary tract infections caused by carbapenem-resistant Enterobacterales, rather than a preferred option. Its urinary activity helps explain this limited role. For invasive infections, treatment selection depends on the organism, its resistance mechanism and which drugs remain active. The guidance favors other agents in many settings and identifies toxicity as an important limitation of polymyxins. [IDSA treatment guidance](https://www.idsociety.org/practice-guideline/amr-guidance/)

When intravenous colistin is necessary, specialists must account for its administration as colistimethate sodium, a precursor converted into active colistin. Kidney function affects dosing decisions, and monitoring helps detect emerging injury. Consensus recommendations also advise avoiding other kidney-toxic medicines where possible. Patients receiving treatment can ask how their kidney function is being monitored and whether an effective alternative is available. [Polymyxin dosing and safety guidance](https://pmc.ncbi.nlm.nih.gov/articles/PMC7437259/)