Combined intravenous and intraventricular administration of colistin methanesulfonate in critically ill patients with central nervous system infection.

Colistin pharmacokinetics were prospectively studied after intravenous administration of colistin methanesulphonate in critically ill patients without central nervous system infection (controls, n = 5) and in patients with external ventricular drain-associated ventriculitis after intravenous administration (EVDViv, n = 3) or combined intravenous/intraventricular administration (EVDVcomb, n = 4). Cerebrospinal fluid (CSF)/serum colistin concentration ratios were higher in EVDViv than in control patients (11% versus 7%, P ≤ 0.05) and in EVDVcomb compared to all other patients (P < 0.0001). CSF colistin concentrations above the MIC of 0.5 μg/ml were achieved only in EVDVcomb patients.