A mouse model for postoperative fatal enteritis due to Staphylococcus infection.
BACKGROUND
Postoperative infection of intestine with methicillin-resistant Staphylococcus aureus (MRSA) is fatal in some cases. The object of this study was to establish a mouse model for the infection, providing a useful tool for investigating mechanisms in the progression of infection.


METHODS
Mice were pretreated with cyclophosphamide, injected orally or directly into jejunum with MRSA prepared from a postoperative patient, and then given 5 daily doses of antibiotics. Forty-eight hours after the injection, bacterial translocation and serum endotoxin levels were examined. Macrophage depletion was carried out by the administration of liposome-encapsulated dichloromethylene diphosphate (Cl(2)MDP), 4 days before MRSA injection.


RESULTS
Injection into the jejunum but not oral administration of MRSA induced enteritis with diarrhea and resulted in death in most cyclophosphamide-treated mice. Translocation of MRSA in mesenteric lymph nodes and liver was observed, concomitantly with E. coli infection. Endotoxin-resistant C3H/HeJ mice infected with MRSA survived longer than endotoxin-sensitive C3H/He mice, but also died within a week after MRSA injection. Selective depletion of macrophages induced infection in mice that were not pretreated with cyclophosphamide.


CONCLUSIONS
We established a mouse model for the fatal MRSA infection which induced enteritis with diarrhea, that will be a useful tool for investigating the mechanisms for sometimes fatal MRSA infection of the intestine in postoperative patients. The presence of E. coli or endotoxin seemed to play a major role in the mortality of mice in the early days of MRSA-induced enteritis, but other factors, probably from MRSA, in the later days. Phagocytes were quite important for protection against the MRSA infection.
Nakamura
Y
Y
Third Department of Surgery, Toho University School of Medicine, 2-17-6 Ohashi, Meguro-ku, Tokyo 153-8515, Japan.
Aramaki
Y
Y
Kakiuchi
T
T
D018712:Analgesics, Non-Narcotic / Q000494:pharmacology; D000818:Animals; D018988:Bacterial Translocation; D004002:Clodronic Acid / Q000494:pharmacology; D003520:Cyclophosphamide; D004195:Disease Models, Animal; D004731:Endotoxins / Q000097:blood; D004760:Enterocolitis / Q000382:microbiology* / Q000401:mortality / Q000601:surgery; D004926:Escherichia coli; D007166:Immunosuppressive Agents; D007583:Jejunum / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology; D008297:Male; D016106:Methicillin Resistance; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D011183:Postoperative Complications / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000401:mortality / Q000601:surgery
D018712:Analgesics, Non-Narcotic; D004731:Endotoxins; D007166:Immunosuppressive Agents; D004002:Clodronic Acid; D003520:Cyclophosphamide