The Retroperitoneum Protects Prosthetic Graft Material from Intraperitoneal Contamination: An Experimental Study

To evaluate the ability of the retroperitoneum to serve as a barrier, against bacterial contamination, between the peritoneal cavity to the retroperitoneal space. Seventy rats had a small piece of knitted Dacron graft placed in the retroperitoneal space and 10 6–10 9 colony forming unit (cfu) Enterococcus faecalis was injected into the peritoneal cavity. In half the retroperitoneal (RP) group, the retroperitoneum was preserved and in the remainder, the open peritoneal (OP) group, needle holes were created. Grafts were harvested after 1, 4, or 7 days and cultured for E. faecalis. A blood sample was collected from three rats in each group for culture before the graft was harvested. Graft infection did not develop in any rat injected with 10 6 or 10 7 cfu in the RP group, while seven out of the 10 graft cultures of the OP group grew E. faecalis ( P=0.003). In rats injected with 10 8 or 10 9 cfu, five out of the 10 graft cultures in the RP group and eight out of 10 in the OP group grew E. faecalis. All blood cultures were negative when the injected bacterial count was 10 7 cfu or less. One out of the three blood cultures was positive at 10 8 cfu, and all were positive at 10 9 cfu. These results suggest that an intact retroperitroneum acts as a protective barrier against intraperitoneal bacterial contamination, particularly when blood cultures are negative.