Immunosuppression and intestinal bacterial overgrowth synergistically promote bacterial translocation.

Gram-negative, enteric bacilli of the indigenous gastrointestinal tract microflora translocated primarily to the mesenteric lymph nodes in mice given either oral penicillin G sodium or clindamycin hydrochloride. These bacteria also translocated to the mesenteric lymph nodes in mice injected with cyclophosphamide or prednisone. However, in mice treated with the combination of an oral antibiotic plus an immunosuppressive drug, the translocating bacteria spread systemically to the peritoneal cavity. When the treatment with clindamycin and prednisone was extended to 12 days, the mice died of lethal sepsis beginning eight days after treatment. Thus, the combination of intestinal bacterial overgrowth and host immunosuppression synergistically promoted bacterial translocation from the gastrointestinal tract that resulted in lethal sepsis.