Variations in ventricular distribution of polymyxin B following intraventricular administration in patients with central nervous system infections.

Polymyxin B (PMB) demonstrates activity against multidrug-resistant Gram-negative pathogens. Intraventricular administration is considered when systemic therapy yields suboptimal cerebrospinal fluid (CSF) levels. We describe two cases of carbapenem-resistant gram-negative meningoencephalitis successfully treated with intraventricular PMB, in which unilateral PMB administration appeared to achieve bilateral ventricular distribution, with higher concentrations on the administration side. A potential association was observed between reduced CSF drainage and increased PMB concentrations. These findings may offer preliminary insights into optimizing PMB dosing strategies for CNS infections.