Listeria monocytogenes infection in pregnant guinea pigs is associated with maternal liver necrosis, a decrease in maternal serum TNF-α concentrations, and an increase in placental apoptosis

Stillbirths and spontaneous abortions can result when pregnant women are exposed to the food borne pathogen, Listeria monocytogenes. Fetuses and neonates account for one-third of the 2500 cases annually. The objectives were to determine the dose dependent trends of immunological and pathological effects in pregnant guinea pigs after infection with L. monocytogenes. Timed pregnant guinea pigs were treated on gestation day (gd) 35 with doses of 104 to 108 colony forming units (CFUs) and sacrificed on gd 56. Hepatic lesions were found in dams treated with ≥105 CFUs. Apoptosis was detected in significantly more placentas from dams treated with ≥106 CFUs compared to controls. Maternal serum TNF-α concentrations were significantly decreased in all dose groups compared to controls. In conclusion, increases in premature delivery, maternal hepatic effects and placental apoptosis along with a decrease in TNF-α concentrations were associated with L. monocytogenes infection in pregnant guinea pigs.