Guiding appropriate use of colistin and polymyxins
Panelists discuss how regulatory incentives are advancing antimicrobial development, enabling a shift away from older, toxic agents like colistin, while acknowledging that despite the superiority of newer therapies, polymyxins still retain a limited role in rare, highly resistant infections where no better alternatives exist.
Efforts to incentivize the development of new antimicrobials through regulatory tools like exclusivity extensions and fast-track designations are beginning to pay off. These programs are designed to encourage pharmaceutical companies to develop treatments for neglected but critical areas of infectious disease—especially drug-resistant pathogens—by offering extended market protection and expedited approval processes. The ultimate goal is to reduce the reliance on older, more toxic antibiotics by providing safer, more effective alternatives.
This raises a long-standing question: Are we finally ready to remove polymyxins—particularly colistin—from hospital formularies? Although new antibiotics have shown superior outcomes compared with polymyxins in clinical trials, full retirement remains complex. Colistin, for example, still has utility in certain cases like urinary tract infections due to its good urinary penetration. However, its use is limited by poor systemic conversion and distribution, making it unreliable for bloodstream or pulmonary infections. Newer antibiotics consistently outperform polymyxins in these settings, but rare scenarios involving resistant organisms without effective alternatives mean colistin still has a narrow, though diminishing, role.
Ultimately, the clinical community now has the data and tools to move away from polymyxins in most situations. Ten years ago, these decisions were made with limited comparative evidence; today, the superiority of newer agents is well established for many high-risk infections. Still, the unpredictable nature of resistance means having backup options—even imperfect ones—remains important. Clinicians must be deliberate when reaching for older agents, ensuring there are truly no better alternatives. The hope is that continued development and stewardship will eventually make routine use of polymyxins obsolete, but for now, their occasional necessity remains a reality in managing complex infections.
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