[Etiology of sepsis occurring in the immunocompromised host and its prevention. 1. Analysis of the bacterial portal of entrance in experimental mice with bacteremia].

Nosocomial infections due to aerobic gram-negative bacilli are life-threatening problems for immunocompromised patients. Most of these infections might arise from the patient's own flora, especially from their faecal flora. The purpose of this study was to investigate the bacterial portal of entry in experimental mice with bacteremia which were treated by cyclophosphamide (CY). It was clarified that almost all of the isolates from blood of CY and antibiotics treated mice were identical with their own faecal flora, and that organisms were isolated in some cases only from the portal vein but not from heart blood. From these results it was concluded that some of the bacteria entered from the intestinal tract through the portal vein to the systemic circulation in the immunosuppressed state. The time course of bacterial translocation were examined with SPF mice which were given Pseudomonas aeruginosa orally prior to CY treatment. Twelve strains of Escherichia coli were isolated, 10 of which were isolated only from mesenteric lymph nodes (MLN). Though six strains of P. aeruginosa were isolated from the heart blood, 4 were not isolated from MLN. It was suggested that translocations of E. coli and P. aeruginosa occurred by lymphogenous and hematogenous routes respectively. And translocation of viable E. coli was observed only after ABPC treatment but before CY inoculation, on the other hand translocation of viable P. aeruginosa was observed after CY inoculation. So only disruption of the normal flora ecology was necessary for translocation of E. coli, but immunosuppression was additionally necessary for translocation of P. aeruginosa.