In 1926, a bacterium was recovered from the livers of rabbits who had become ill during a laboratory epidemic. The illness was septicemic in nature and characterized by marked peripheral monocytosis and the development of necrotic foci in the liver. The report of these events by Murray and co-workers1 provided the first description of disease due to the organism now known as Listeria monocytogenes. The name "L monocytogenes" was chosen because of the mononuclear cell response observed in rabbits, guinea pigs, and gerbils infected with this organism. It should be emphasized at the outset that human infections usually are characterized by a polymorphonuclear response in peripheral blood, cerebrospinal fluid, and tissues.
During the last 50 years, this organism has been reported to cause infection in 42 domestic and feral mammalian species and 22 avian species.2 It also has been isolated from animal feeds, soil, water, and sewage and has