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Identification of Salmonella enteritidis from Experimentally Infected Hens Using a Colorimetric DNA Hybridization Method

P. F. Cotter, J. E. Murphy, J. D. Klinger and R. L. Taylor, Jr.
Avian Diseases
Vol. 39, No. 4 (Oct. - Dec., 1995), pp. 873-878
DOI: 10.2307/1592426
Stable URL: http://www.jstor.org/stable/1592426
Page Count: 6
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Identification of Salmonella enteritidis from Experimentally Infected Hens Using a Colorimetric DNA Hybridization Method
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Abstract

Identification of Salmonella enteritidis from cloacally challenged commercial laying hens was studied by comparing bacterial isolations using conventional methods with detection by the use of the GENE-TRAK® colorimetric DNA probe assay. More positive test results were obtained using the latter on days 14, 28, and 42 postchallenge, but the difference between the two methods was not statistically significant. Over the duration of the experiment, positive cloacal samples were statistically more frequent from a commercial strain of white leghorn hens when compared with a commercial brown egg-producing strain (28/60 vs. 9/57; chi-square 1 df = 12.9, P < 0.001). Eggs having various shell defects were produced by the infected hens only after Salmonella challenge. These defects included, in order of frequency, elongated shape, thin shells, off-white color (tints), small size, wrinkles, and pimples. No Salmonella could be recovered from 193 defective eggs, nor were positive isolates made from additional tests performed on 50 normal eggs. Proteus sp. was isolated from 10 eggs, however. Our observations demonstrate that the GENE-TRAK colorimetric method is comparable with conventional bacteriology for the identification of Salmonella in cloacal samples taken from laying hens. Moreover, the two methods demonstrate the existence of breed differences in susceptibility to S. enteritidis challenge. /// Se estudió la identificación de Salmonella enteritidis a partir de gallinas ponedoras desafiadas por la vía cloacal. Se compararon los métodos convencionales de aislamiento bacteriano con el uso de la sonda colorimétrica del ácido desoxiribonucléico, Gene-Track®. Con este último método se obtuvieron mayores resultados positivos a los 14, 28 y 42 días después del desafío, pero no hubo una diferencia estadísticamente significante entre los dos métodos. Durante el experimento, las muestras cloacales positivas fueron estadísticamente más frecuentes en las gallinas de una estirpe comercial leghorn blanca que en una estirpe comercial de huevo marrón (28/60 vs. 9/57: Chi-cuadrado 1 gl = 12.9 P < 0.001). En las gallinas infectadas, se obtuvieron huevos con varios defectos en la cáscara sólamente después del desafío. Estos defectos incluyeron huevos alargados, con cáscara delgada, pérdida de color, tamaño reducido y huevos con cáscaras arrugadas y granulosas. No se pudo aislar la Salmonella de ninguno de los 193 huevos defectuosos ni de un grupo de 50 huevos normales. Sólamente se aisló Proteus sp. de 10 huevos. Los resultados demostraron que el método colorimétrico Gene-Trak® es comparable con el método bacteriológico convencional para la identificación de Salmonella en muestras tomadas de la cloaca de ponedoras comerciales. Además, los dos métodos demostraron diferencias en la susceptibilidad entre las estirpes frente al desafío con S. enteritidis.

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