Collagen changes around intestinal anastomoses in germ-free rats

The changes in collagen, measured as hydroxyproline, concentration around both ileal and colonic anastomoses in germ-free and control rats have been investigated and compared with each other. The germ-free rats were raised, operated on and maintained under completely pyrogen-free conditions. Animals were killed 2, 3 or 7 days after operation. There was a significant reduction in the lowering of hydroxyproline concentrations around the colonic anastomosis of germ-free rats compared with control rats both in the anastomosis at days 2 and 3 (P = 0.04 and P = 0.006 respectively) and in the proximal segment at day 3 (P = 0.03). In ileal anastomoses, significant differences between control and germ-free rats were only found at 7 days. Here, the increase in hydroxyproline concentration observed in control rats was significantly reduced in germ-free rats. These data are taken to support the hypothesis that bacteria affect colonic anastomotic healing by contributing to postoperative collagen degradation.