Rifamycin lavage in the treatment of experimental intra-abdominal infection

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

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.

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.

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