Yersinia enterocolitica infection in pregnant mice and their offspring

In order to investigate the susceptibility to Yersinia enterocolitica infection before and during pregnancy, and the potential vertical transmission to the offspring, female adult mice were intravenously inoculated with 3 x 10(4) CFU of Y enterocolitica either 7 days before conception or on day 8 of pregnancy. Infection was assessed by determining the number of bacterial counts in spleen of mothers, entire body of fetuses, placentas, and spleen of newborns. Mice challenged 7 days before pregnancy had cured at the time of mating. Pregnancy did not reactivate infection. In contrast, mice challenged at day 8 of pregnancy showed an intense reactivation of the splenic infection from day 15 of pregnancy to delivery. Moreover, they gave birth to live offspring, that were or were not infected, and to stillborn pups that were heavily infected. Splenic infection of mothers and living offspring that had been congenitally infected, cured by 8 days after delivery.