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Pathotypes of Avian Escherichia coli as Related to tsh-, pap-, pil-, and iuc-DNA Sequences, and Antibiotic Sensitivity of Isolates from Internal Tissues and the Cloacae of Broilers

Musangu Ngeleka, Lena Brereton, Gabriel Brown and John M. Fairbrother
Avian Diseases
Vol. 46, No. 1 (Jan. - Mar., 2002), pp. 143-152
Stable URL: http://www.jstor.org/stable/1592797
Page Count: 10
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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.
Pathotypes of Avian Escherichia coli as Related to tsh-, pap-, pil-, and iuc-DNA Sequences, and Antibiotic Sensitivity of Isolates from Internal Tissues and the Cloacae of Broilers
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Abstract

One hundred four Escherichia coli isolates were collected from internal tissues and the cloacae of broilers with colibacillosis or from the cloacae of healthy birds. The isolates were tested for the presence of DNA sequences for temperature-sensitive hemagglutinin (tsh), for P (pap) and F1 (pil) fimbriae, and for aerobactin synthesis (iuc) by DNA/DNA hybridization. The isolates were also tested for O1, O2, and O78 serogroups, serum and antibiotic resistance, and virulence in day-old chickens. The Tsh/Pil/Iuc was the major pathotype detected in 53.8% of isolates from internal tissues, as compared with only 28.8% of isolates from the cloacae. The Tsh/Pap/Iuc pathotype was detected at a lower frequency (15.4%) but only in isolates from internal tissues. Among the virulence-associated marker genes, tsh and iuc were detected in most of the isolates from internal tissues (90.4% and 92.3%), as compared with only 51.9% and 63.5% of isolates from the cloacae, respectively. pap was detected to a lesser extent, in 25% of isolates but only from internal tissues. In contrast to the pil gene, the tsh-, pap-, and iuc-DNA sequences were more frequently detected in isolates from internal tissues than in isolates from the cloacae. O-antigen typing revealed that 25% of isolates belonged to serogroups O1 (4.8%), O2 (9.6%), and O78 (10.6%). Although most isolates appeared to be resistant to serum, only isolates from internal tissues were virulent in day-old chickens in contrast to isolates from the cloacae. More than 10% of isolates were resistant to most of the antibiotics used for the study. However, less resistance to enrofloxacin and norfloxacin was observed. Our data suggest that the Tsh/Pil/Iuc and Tsh/Pap/Iuc pathotypes and Tsh and Iuc virulence-associated markers are important factors of avian pathogenic E. coli. Enrofloxacin appeared to be the best choice for treatment of the infection. /// Se colectaron 104 aislamientos de Escherichia coli a partir de tejidos internos y de cloaca de pollos de engorde con colibacilosis y de pollos sanos. Los aislamientos se analizaron mediante hibridación de ADN con ADN para detectar la presencia de las secuencias de ADN codificantes para la hemoaglutinina termosensible (tsh), para las fimbrias tipo P (pap) y F1 (pil), así como para la síntesis de aerobactina (iuc). Los aislamientos también se analizaron para determinar si pertenecían a los serogrupos O1, O2 ó O78. Finalmente, los aislamientos se estudiaron para determinar su resistencia a suero, antibióticos y para determinar su virulencia en pollos de un día. Las bacterias Tsh/Pil/Iuc resultaron ser el patotipo principal, que se detectaron en 53.8% de los aislamientos de tejidos internos, en comparación con solo 28.8% de los aislamientos de cloaca. El patotipo Tsh/Pap/Iuc se detectó con menor frecuencia (15.4%) pero solo en aislamientos de órganos internos. Entre los genes marcadores asociados con virulencia, se detectaron tsh e iuc de la mayoría de los tejidos internos (90.4% y 92.3%), en comparación con solo 51.9% y 63.5% de los aislamientos de cloaca, respectivamente. El marcador pap se detectó con menor frecuencia en 25% de los aislamientos y únicamente en tejidos internos. A diferencia del gen pil, las secuencias de DNA tsh, pap, y iuc se detectaron con mayor frecuencia en aislamientos de tejidos internos en comparación con aislamientos de la cloaca. La serotipificación con el antígeno O reveló que 25% de los aislamientos pertenecían a los serogroupos O1 (4.8%), O2 (9.6%), y O78 (10.6%). Aunque la mayoría de los aislamientos parecían ser resistentes al suero, solo los aislamientos de tejidos internos fueron virulentos en pollos de un día de edad a diferencia de los aislamientos de cloaca. Más del 10% de los aislamientos fueron resistentes a la mayoría de los antibióticos usados en el estudio. Sin embargo, se observó una resistencia menor a la enrofloxacina y a la norfloxacina. Los datos de este estudio sugieren que los patotipos Tsh/Phil/Iuc y Tsh/Pap/Iuc así como los marcadores asociados con la virulencia Tsh e Iuc son factores importantes para E. coli patogénica aviar. La enrofloxacina pareció ser la mejor opción para el tratamiento de la infección.

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