Estudio de inocuidad de Salmonella entérica, subespecie entérica, serotipo Enteritidis, var Danysz lisina negativa en pollos parrilleros

Abstract

Se realizó un estudio con la cepa Salmonella enterica, subespecie entérica, serotipo Enteritidis, var. Danysz lisina negativa, principio activo de un producto comercial usado para el control biológico de roedores. Evaluándose su inocuidad en pollos parrilleros. Se usaron 120 aves de 1 día de edad de la linea Cobb Vantress divididas en 3 grupos, con igual porcentaje de hembras y machos. El grupo A fue alimentado los días 5, 6 y 7 de edad con un alimento comercial que contenía 20% del producto raticida. El grupo B fue inoculado al 8vo día de edad directamente al buche con 1 ml. de 108 UFC de la bacteria. El tercer grupo permaneció como control. Se registraron signos clínicos y mortalidad diaria, peso corporal individual semanal, recuperación de la cepa de Salmonella usada y reapuesta serológica. A partir del quinto día postinoculación y durante una semana, dos aves de cada grupo fueron necropsiadas. Adicionalmente se tomaron muestras de sangre a todos los grupos a los 21, 28 y 35 días post inoculación y en aves sacrificadas, para detectar anticuerpos a Salmonella mediante la prueba de aglutinación en placa. Los resultados del estudio bacteriológico, y de las pruebas serológicas realizadas entre el día 5 a 12 post desafio fueron negativos a Salmonella spp. No se encontraron lesiones macroscópicas compatibles con infección por Salmonella, sin embargo a los 28 y 35 días post desafio las aves del grupo A dieron 5.5% a los 28 días (1/18) y 16.6% a los 35 días de edad (3/18) aves positivas a la prueba de aglutinación para Salmonella spp.. las aves que reaccionaron serológicamente fueron sometidas a una evaluación bacteriológica, se aisló Salmonella spp. tipificada como lisina positiva. Los pesos corporales a la sétima semana no mostraron diferencias significativas entre grupos.

The Salmonella enterica serotipe Enteritidis var Danysz negative lysine strain is used as a component of a product for biological control of rodents. This product is a mixture of grains containing the strain. The present study evaluated whether the strain was innocuous for chickens or not. One hundred and twenty day – old Cobb Vantress broiler chicks (50% each sex) were divided into 3 groups of 40 chicks each. Four chicks per group were separated to verify if they were free from Salmonella spp. The group A was fed with standard broilers food containing 20% of the product for biological rodent control. The group B received 1 ml containing 108 CFU of Salmonella enterica serotipe Enteritidis var Danysz negative lysine by crop gavage at eighth day. The group C was kept as uninoculated control group. Clinical signs, mortality, recovery strain used in the experiment, body weight, and serological response were recorded. Chicks were observed daily for clinical signs and mortality. Bacteriological cultures were made in order to recover the microorganism from liver and spleen. All birds were weighed every week. Two chicks were randomly selected from each treatment group, euthanatized, and necropsied since the fifth day during one week. Serum samples and select tissues (liver and spleen) were collected for bacteriological culture. Additionally, serum samples were collected from each group in the 21st , 28th and 35th days postinoculation. The results of bacteriological work of select tissues (direct and indirect cultures) and the serological study of serum samples tested negative for Salmonella spp. Positive birds to the agglutination test to Salmonella spp. were found only in the group A. It was found 5.5% at 28 days and 16.6% at 35 days of age. The positive birds were submitted to a bacteriological evaluation; in one of them Salmonella spp was isolated and typified by biochemistry as positive lysine. Significant weight differences among groups recorded in the seventh week, were not found.