Rifamycin lavage in the treatment of experimental intra-abdominal infection

Hypothesis: Peritoneal lavage with rifamycin reduces the number of intraperitoneal bacteria and adhesions and improves the outcome of intra-abdominal Infection (IAI).

Material and methods: Experimental IAI was induced in Wistar rats. After 24 h, the Animals underwent relaparotomy. A peritoneal fluid sample was obtained and lavage of the abdominal cavity was performed. Animals were randomly assigned to the three following groups: lavage with 0.9% sodium chloride solution (S group); lavage with rifamycin at the dose of 25 mg/kg (R25 group); and lavage with rifamycin at the dose of 12.5 mg/kg (R12.5 group). Mortality was recorded every 8 h for 7 d. All Animals that died had a necropsy. Surviving rats were later sacrificed and also underwent a necropsy. At necropsy, intraperitoneal adhesions were noted and a peritoneal fluid sample was obtained for Bacterial analysis.

Results: Peritoneal lavage with rifamycin improved survival from 50% in the S group to 91.7 and 100% in the R25 group and R12.5 group, respectively. Adhesion formation was significantly reduced in the R25 group and R12.5 group compared with the S group (P < or = 0.01 and P < 0.01, respectively). There was a greater reduction in Bacterial counts in peritoneal fluid in the R25 group compared with the S group (P = 0.003) but there was no significant difference in the reduction of Bacterial count between R25 group and R12.5 group.

Conclusion: These results suggest that peritoneal lavage with rifamycin improves the outcome of IAI.