Peritonitis in Nude Mice in a Xenograft Study

After 30 Sim: (NCR) nu/nu mice were anesthetized with intraperitoneal tribromoethanol, they were injected with 106 human breast cancer cells or phosphate buffered saline (PBS) into the mammary fat pad through a surgical incision. Over the next six days, 24 of 30 mice became ill or died. Necropsies showed peritonitis, and a variety of bacteria were isolated from the peritoneal cavities of the mice. The tribromoethanol solution, PBS solution, and neoplastic cell line were all cultured and were microbiologically negative. Three immunocompetent mice were subsequently injected intraperitoneally with the same tribromoethanol solution used for the 30 nude mice. All three of the immunocompetent mice showed histologic evidence of peritonitis, but only one yielded positive peritoneal bacterial cultures and showed gross evidence of peritonitis. The tribromoethanol solution, previously reported to cause peritonitis, likely induced a chemical peritonitis in these mice, and the bacteria isolated were a secondary infection from normal gastrointestinal flora. We conclude that adequate mixing and storage of tribromoethanol are essential and that it is a safe and effective anesthetic when properly used.