Intrathecal colistin and sterilization of resistant Pseudomonas aeruginosa shunt infection

OBJECTIVE: To report 2 cases of multidrug-resistant (MDR) Pseudomonas aeruginosa meningitis and ventriculo-peritoneal shunt (VPS) infection successfully sterilized with intrathecal colistin 10 mg/day after development of nephrotoxicity associated with intravenous administration. CASE SUMMARIES: Case 1. A 69-year-old African American woman with a history of subarachnoid hemorrhage and hydrocephalus requiring VPS placement was admitted with VPS infection and meningitis. Cerebrospinal fluid (CSF) cultures revealed MDR P aeruginosa susceptible only to colistin. Intravenous colistin was initiated but rapidly discontinued due to development of renal dysfunction. Intravenous colistin was the probable cause of the adverse effect. Intrathecal colistin was initiated via an externalized VPS, with subsequent improvement in white blood cell counts in the CSF. Follow-up CSF cultures remained sterile and renal function returned to baseline. Case 2. A 69-year-old white woman with a history of subarachnoid hemorrhage, hydrocephalus, and VPS was transferred from an extended-care facility for management of a VPS infection. CSF cultures revealed MDR P aeruginosa susceptible only to colistin. Intravenous colistin was initiated but subsequently discontinued due to worsening renal function that, as with the first case, probably correlated with colistin administration and persisted despite dose adjustment. Therapy was changed to intrathecal administration, with subsequent normalization of her CSF white blood cell counts and sterilization of cultures. DISCUSSION: The limited availability of antibiotics for treatment of highly resistant or MDR gram-negative organisms has prompted clinicians to reconsider the use of older drugs. Prior reports have suggested that intravenous colistin is a potential alternative for treating highly resistant gram-negative central nervous system infections, specifically Acinetobacter, but its use is limited by nephrotoxicity. Our experience suggests that intrathecal colistin is a potentially curative intervention for the treatment of severe MDR P. aeruginosa meningitis and VPS infections in patients in whom intravenous colistin is not an option. CONCLUSIONS: Intrathecal use of colistin is a potentially safe, effective, and viable treatment option for MDR P. aeruginosa central nervous system infections when intravenous administration is not feasible.