Indwelling pleural catheter is an established management for malignant pleural effusions. Extending its use to patients with malignant ascites by insertion of a catheter intraperitoneally enables regular outpatient drainage and improves quality-of-life. However, indwelling pleural/peritoneal catheter (IPC/IPeC) is associated with catheter-related infections, traditionally managed with systemic antibiotics and occasionally requires catheter removal. Direct administration of antibiotics intra-abdominally via peritoneal dialysis (PD) catheters is a well-established, efficacious practice in PD-related peritonitis and minimizes systemic adverse effects. We applied the same principles to a patient with peritoneal mesothelioma who developed peritonitis 3 weeks after insertion of IPeC. Intraperitoneal vancomycin was administered via, and compatible with, the IPeC. The patient tolerated the treatment without adverse effects and made a full recovery without requiring catheter removal.