Preterm delivery in mice with renal abscess.

OBJECTIVE

Our purpose was to develop a mouse model of renal abscess to study the effect of extrauterine infection on preterm delivery.

METHODS

Escherichia coli or sterile medium was injected into the left kidney of 70 pregnant mice that had completed approximately 75% of gestation. Preterm delivery rates were recorded for various inocula. Kidney specimens were obtained and examined grossly and histologically for abscess formation.

RESULTS

Thirty-one of 51 animals (60.8%) infected with 1 x 10(5)-9 x 10(6) bacteria and none of 19 uninfected animals delivered prematurely (P < .001). Renal abscess was induced in 100% of mice receiving bacterial inoculation but in none receiving sterile medium.

CONCLUSION

Kidney injection provides a reliable method for inducing renal abscess in pregnant mice. Renal abscess induces preterm delivery at a stable rate across a wide range of bacterial inocula. This model of extrauterine infection may be particularly useful in investigations of infection-induced preterm delivery.