The University of Georgia College of Veterinary Medicine

Georgia Veterinary Scholars Program

GVSP Summer 2011 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Knox Hilliard UGA College of Veterinary Medicine Class of 2014	Dr. Mary Alice Smith Department of Environmental Science UGA College of Public Health

Isolation of Listeria monocytogenes from various organs after oral exposure to adult female gerbils

Knox Hilliard, Jill Fishburn, Mary Alice Smith

Listeria monocytogenes is a gram positive food-borne obligate intracellular pathogen that causes a range of disease symptoms in both animals and humans such as gastroenteritis, meningitis, and fetal death. The vast majority of cases of listeriosis occur in pregnancy, immunocompromised patients and the elderly.

Disease dissemination requires that the bacteria invade host cells, and current data suggest that interactions through host E-cadherin and Met receptor proteins and bacterial InlA and InlB proteins aid in invasion, respectively. The gerbil has been proposed as an ideal test subject for studying listeriosis because unlike the mouse or guinea pig, it displays both the E-cadherin and Met receptor proteins on the outer surface of its cells.

The purpose of this study is to investigate the dissemination of listeriosis in an animal model containing both the E-cadherin and Met receptors. Four female gerbils were challenged with 2.3x108 CFU of Listeria monocytogenes 12443 strain (a rhesus monkey isolate). Their fecal samples were collected daily and selectively cultured for the presence of L. monocytogenes, and upon sacrifice seven days after the initial treatment, samples of blood, brain, kidney, thymus, mesenteric lymph nodes, liver, gall bladder, spleen, pancreas, cecum, jejunum and colon were taken and selectively cultured for the presence and enumeration of L. monocytogenes.

The bacteria was found to be present in the pancreas of two subjects, a novel finding in the dissemination of listeriosis. There were also positive results in much of the lower intestinal tract in all subjects through enrichment methods despite a lack of presence in all collected fecal samples. Additionally, Listeria was detected in the brain tissue of two of the four subjects, a site very common in human infections.