A model of intrauterine infection and preterm delivery in mice.
OBJECTIVE
Our purpose was to determine whether intrauterine bacterial inoculation leads to preterm delivery in mice.


METHODS
Fifty-four female CD-1 mice at 75% of the length of the gestational period (14.5 days) received either an intrauterine bacterial inoculum of 2 to 10 x 10(3) Escherichia coli (n = 33), an intraperitoneal bacterial inoculum (n = 7), or an intrauterine injection of a sterile solution (n = 14).


RESULTS
Delivery within 48 hours of surgery occurred in 91% of mice after intrauterine bacteria, in 0% after intraperitoneal bacteria, and in 7% after sterile intrauterine injection (p < 0.001). Intrauterine bacterial inoculation produced systemic infection (i.e., recovery of organisms from culture of the heart) in 50% of animals post partum. Intraperitoneal bacteria and intrauterine saline solution injections resulted in systemic infection rates of 20% and 0%, respectively, 48 hours after surgery. Five of seven animals injected with bacteria into the uterus had histologic evidence of metritis, mild in all cases. Intrauterine bacterial inoculation resulted in induction of ribonucleic acid transcripts for tumor necrosis factor-alpha, interleukin-1 alpha, interleukin-1 beta, and cyclooxygenase-2.


CONCLUSIONS
Intrauterine inoculation with Escherichia coli in mice leads to preterm delivery and the local induction of factors known to be involved in human preterm labor with infection. The observation that intraperitoneal bacterial inoculation does not result in preterm delivery suggests that in this model labor is the product of a local (uterine) stimulus.
Hirsch
E
E
Department of Obstetrics and Gynecology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Saotome
I
I
Hirsh
D
D
D000818:Animals; D016009:Chi-Square Distribution; D004195:Disease Models, Animal; D004927:Escherichia coli Infections / Q000150:complications* / Q000378:metabolism / Q000382:microbiology; D005260:Female; D007375:Interleukin-1 / Q000096:biosynthesis; D051379:Mice; D008815:Mice, Inbred Strains; D007752:Obstetric Labor, Premature / Q000209:etiology* / Q000378:metabolism; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000378:metabolism / Q000382:microbiology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis; D012313:RNA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D014591:Uterine Diseases / Q000150:complications* / Q000378:metabolism / Q000382:microbiology
D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D011451:Prostaglandin-Endoperoxide Synthases