Prevention of Ommaya Reservoir–Associated Bacterial Meningitis With Prophylactic Intraventricular Vancomycin

BACKGROUND AND OBJECTIVES: Intraventricular chemotherapy administered through an Ommaya reservoir (OmR) constitutes an integral part of therapy for patients with leptomeningeal metastasis. Unfortunately, OmR infections remain a frequent, costly, morbid, and occasionally fatal complication, limiting the benefit of this approach. We evaluate the efficacy, cost savings, and toxicity of vancomycin coadministered with intraventricular chemotherapy for the prevention of OmR-associated bacterial meningitis. METHODS: This was a cohort study comparing a treatment group treated from May 1, 2021, to April 30, 2022, and a retrospective control group treated from 2016 to 2021. Patients were included if they had a diagnosis of leptomeningeal metastasis and subsequent placement of an OmR, followed by delivery of planned intraventricular chemotherapy. Patients in the treatment group received a 10-mg dose of intraventricular vancomycin in addition to their standard chemotherapy regimen at each treatment. We compared this group to a retrospective cohort from the preceding 5 years who did not receive intraventricular vancomycin, evaluating the rate of infection, adverse events, and associated treatment costs between groups. RESULTS: The infection rate was 0% (95% CI 0%-6.75%) among the 63 patients and 0% (0%-0.76%) in the 501 consecutive treatments administered over the 12-month study period, compared with 10.25% (7.39%-14.0%) among the 322 patients and 1.71% (1.22%-2.39%) in 1932 treatments over the preceding 5 years. The absolute risk reduction was 10.3% (3.83-14.04), P = .0028. The number needed to treat was 10 (7-26). Cost per vancomycin dose was $10.00 ($5010 over 12 months). The cost of nonsurgical treatment of 1 OmR-associated infection is $88 372, which translates into $618 604 for the estimated 7 patients over 12 months who developed an OmR-associated infection. No treatment-associated toxicity was observed. CONCLUSION: Prophylactic intraventricular vancomycin eliminated OmR-associated infections without added toxicity and with dramatic cost savings.