Background: Infectious postoperative complications often delay systemic chemotherapy after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CS-HIPEC). Because the authors have empirically observed fewer incisional infectious complications than expected after CS-HIPEC with mitomycin C (MMC), they investigated the antimicrobial properties of HIPEC perfusate fluid.
Methods: This study prospectively measured in vitro bacterial growth inhibition by HIPEC perfusate (n = 18). After 10 µL of perfusate had been plated on agar plate inoculated by standard strains of either Escherichia coli (strain 25922) or Staphylococcus aureus (strain 25923), it was incubated at 37 °C for 24 h. Antimicrobial activity evidenced by a zone of complete growth inhibition was measured in millimeters. These were compared against growth inhibition produced by control groups represented by MMC solution in normal saline (MMC concentrations of 2, 4, 6, 8, and 8.75 µg/mL), 7 per group.
Results: Bacterial inhibition by HIPEC perfusate was stronger against E. coli than against S. aureus (13.1 ± 6.8 vs 8.3 ± 7.7 mm; p = 0.005). No E. coli inhibition was observed for MMC saline in concentrations of 2 through 8 µg/mL (p < 0.001 each), and inhibition of 4.5 ± 5.7 mm was observed for an MMC saline concentration of 8.75 µg/mL (p = 0.007). The S. aureus inhibition zones by MMC saline solutions were 2.2 ± 2.1 (p = 0.002), 5.1 ± 2.3 (p = 0.135), 7.5 ± 1.0 (p = 0.654), 9.6 ± 0.9 (p = 0.058), and 10.2 ± 0.4 mm (p = 0.021).
Conclusion: The antimicrobial properties of HIPEC perfusate are considerable but variable between patients and stronger against E. coli than against S. aureus. Further studies of HIPEC carrier solutions and chemotherapy agents may result in reduction of surgical-site infection and thus enhanced patient recovery.