Polymyxin B: a new strategy for multidrug-resistant Gram-negative organisms

Background: There has been a renewed interest in using polymyxin B as a last resort therapeutic option, due to emergence of multidrug-resistant Gram-negative bacteria. Despite being available for clinical use for decades, there is still a very limited understanding on many aspects of this agent. Objective: To review what is known about polymyxin B and to identify missing information or gaps for future investigations. Methods: Pertinent information was reviewed from published literature in English. Results/conclusion: For optimal use of polymyxin B, a more thorough understanding is needed on standardized susceptibility testing, serum and tissue concentrations achieved, antibacterial activity when polymyxin B is combined with other agents, and mechanisms of resistance. A more precise characterization of the relationship between drug concentration and toxicity is also required.