Modulation of chronic enteric infection by distant oral infection.

This investigation determined the effects of a distant oral infection (Porphyromonas gingivalis) on a concurrent local enteric infection (Echerichia coli). A modified murine subcutaneous tissue chamber model was used. Subcutaneously implanted chambers with different microbial makeups were monitored for sloughing and their contents assayed for prostaglandin E2. Bilaterally implanted chamber experiments revealed that a distant "chronic" (immunization with heat-killed organism, followed by live challenge) P. gingivalis infection offered protection against a local chronic E. coli infection, as evidenced by delaying the time for 50% of the chambers to reject from day 19 to day 25 and a statistically significant prostaglandin E2 decrease from 529.4 +/- 176.6 ng/ml to 191.5 +/- 100.9 ng/ml (p < 0.01) (Mann-Whitney test). An acute (live challenge only) distant P. gingivalis infection or immunization with the heat-killed organism alone had no effect on "chronic" E. coli infection in this model. These data suggest that the presence of low-grade chronic oral infection may modify the responses to other infectious challenges.