Listeria monocytogenes is a Gram-positive rod-shaped bacterium. It is the causative agent of listeriosis, a serious infection caused by eating food contaminated with the bacteria. The disease generally affects older adults, pregnant women, newborns, and adults with weakened immune systems. However, rarely, persons without these risk factors can also be affected (CDC 2012; Todar 2012).
The overt form of the disease has mortality greater than 25 percent. The two main clinical manifestations are sepsis and meningitis. Meningitis is often complicated by encephalitis, a pathology that is unusual for bacterial infections (Todar 2012).
Czuprynski et al. ( 2003) studied susceptibility of C57BL/6 mice and A/J mice to Listeria monocytogenes (strain Scott A) inoculating them intragastrically (Czuprynski, Faith et al. 2003). Similarly, Golnazarian et al. (1989) also compared infectious dose in normal and compromised C57BL/6J mice with pathogens( strain F5817) via oral route (Golnazarian, Donnelly et al. 1989).