The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholars Program

GVSP Summer 2009 Scholars

Georgia Veterinary Scholar

Faculty Mentor

Lauren LeBlanc
University of Georgia
Class of 2012

Dr. Mary Alice Smith
Environmental and Health Sciences

UGA College of Public Health

Yogurt in the prevention of infection by Listeria monocytogenes

* L. LeBlanc under the direction of M.A. Smith

Listeria monocytogenes (L. monocytogenes), a foodborne pathogen, can invade pregnant hosts, cross the placenta, infect the fetus, and result in stillbirths. L. monocytogenes has the highest case/fatality ratio of any foodborne pathogen. Our objective was to test the in vivo efficacy of yogurt containing Lactobacillus and Bifidobacterium in the prevention of infection following exposure to L. monocytogenes in a pregnant guinea pig model. The dam was considered the experimental unit (N=1). Guinea pigs were treated with 5ml of commercially available yogurt on gestation days (gd) 33 through 36 and were inoculated on gd 35 with 10^9 CFU of L. monocytogenes in sterile whipping cream; the guinea pigs were sacrificed on gd 56. L. monocytogenes were cultured from 57% of maternal liver samples from pregnant guinea pigs as well as 50% of non-pregnant guinea pig liver samples. L. monocytogenes was recovered from 14% of pregnant guinea pig spleen samples. Of seven pregnant guinea pigs, one dam spontaneously aborted a litter of nine pups; L. monocytogenes was cultured from 100%, 100%, and 89% of this litter’s fetal liver, placenta, and brain samples, respectively. All other dams carried viable litters to the day of sacrifice and 0% of fetal liver, brain, and placenta samples yielded L. monocytogenes. Previous studies performed by our lab have shown 75% of pregnant guinea pigs treated with 10^8 CFU L. monocytogenes alone to have stillbirths compared to 14% when treated with yogurt and L. monocytogenes. Thus, yogurt appears to have a protective effect for L. monocytogenes infection.