Detection of Listeria monocytogenes in a beef cattle herd in which previously occurred a clinical case of nervous listeriosis

Abstract

Listeriosis is a disease associated with the consumption of food contaminated with bacteria of the genus Listeria. This study was carried out in an extensive beef cattle operation. The aims were to confirm the clinical suspicion of nervous listeriosis in a beef cattle, to detect asymptomatic carriers of Listeria sp. within the herd and to establish the presence of bacteria of the genus Listeria in pastures and drinking water from the farm. A cow showed circling, decubitus and death. Necropsy was performed and Listeria monocytogenes was isolated from the central nervous system (CNS). Suppurative meningoencephalitis with multiple microabscesses was observed in the brainstem and positive L. monocytogenes immunostaining was detected. Two asymptomatic cows were shedding L. monocytogenes and six were shedding L. inocua in feces. Listeria sp. was not isolated from pasture samples, while L. innocua was isolated in the water sample from the stream. L. monocytogenes isolates from CNS and another from an asymptomatic carrier cow were typified as serotype 4b profile, and the other one as serotype 1/2a. Both serotypes belong to the most commonly reported worldwide in humans and animals diseases, as well as in foods for human consumption nationwide. More epidemiological studies are necessary in beef and dairy cattle operations of Uruguay in order to investigate the dispersion of the agent, establish its relationship with cases of listeriosis in humans and design/apply control measures that reduce its dissemination among animals.