Detección de Listeria monocytogenes en un rodeo de bovinos de carne en el que previamente ocurrió un caso clínico de listeriosis nerviosa

Abstract

espanolListeriosis es una enfermedad asociada al consumo de alimentos contaminados con bacterias del genero Listeria. Este trabajo se realizo en un sistema de cria extensiva de bovinos. Los objetivos fueron confirmar la sospecha clinica de un caso de listeriosis nerviosa en un bovino de carne a pastoreo, detectar la presencia de portadores asintomaticos de Listeria sp. en el rodeo y establecer la presencia de bacterias del genero Listeria en pasturas y agua de bebida del predio. Se realizo la necropsia de una vaca de cria que presentaba marcha en circulos, decubito y muerte. En sistema nervioso central (SNC) se recuperaron colonias de Listeria monocytogenes, mientras que en la histopatologia se observo meningoencefalitis supurativa con multiples microabscesos en tronco encefalico e inmunomarcacion positiva a L. monocytogenes. Se detectaron dos vacas de cria portadoras asintomaticas que excretaban L. monocytogenes y seis que excretaban L. innocua en materia fecal. En las muestras de pasturas no hubo aislamiento, mientras que en la muestra de agua de arroyo se recupero L. innocua. El aislamiento de L. monocytogenes obtenido de SNC y otro de una vaca portadora asintomatica se tipificaron como perfil de serotipo 4b, el restante se tipifico como perfil 1/2a. Estos serotipos coinciden con los mas comunmente reportados a nivel mundial en casos humanos y animales, asi como en alimentos para consumo humano a nivel nacional. Es necesario continuar los estudios epidemiologicos en los sistemas de produccion carnica y lechera de Uruguay para conocer la dispersion del agente, establecer su relacion con casos de listeriosis en humanos y disenar/aplicar medidas de control adecuadas que disminuyan su diseminacion entre animales de produccion. Palabras clave: Rumiante, romboencefalitis, pastoreo EnglishListeriosis 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. Key words: ruminant, rhombencephalitis, grazing