TY - JOUR

T1 - Variations in virulence of avian pathogenic Escherichia coli demonstrated by the use of a new in vivo infection model

AU - Pors, Susanne Elisabeth

AU - Olsen, Rikke Heidemann

AU - Christensen, Jens Peter

N1 - Copyright © 2014 Elsevier B.V. All rights reserved.

PY - 2014

Y1 - 2014

N2 - Salpingitis and peritonitis are common pathological manifestations observed in egg-laying hens. To improve methods to study these conditions, a surgical model was developed. Initially, eighteen white layers underwent laparotomy with subsequent inoculation of ink, bacteria or sterile broth directly into the oviduct. Eight birds inoculated with 0.1 ml blue ink were euthanized immediately after inoculation and the specific site of inoculation was assessed. In all birds, ink was injected into the oviduct between five and seven cm cranial to the isthmus. To demonstrate the use of this approach to cause infection of the oviduct, five birds were inoculated with 8.6 × 10(6)CFU of a clinical Escherichia coli isolate. Five control birds received broth with no bacteria. Both infected and control birds were euthanized after 48 h followed by a post mortem examination. Infected birds showed diffuse fibrino-purulent peritonitis, E. coli was found in pure culture from one or more positions in the oviduct and the liver. Birds receiving sterile broth did not culture positive and demonstrated no gross lesions. Subsequently, 19 birds were inoculated with an isolate of E. coli ST95 and 20 birds with an isolate of E. coli ST141. Major variation in virulence was observed between the two isolates used in relation to clinical signs, gross lesions and histopathology. In contrast to E. coli ST141, E. coli ST95 caused severe clinical signs, epithelial necrosis of the oviduct and purulent salpingitis. The results of the study show the potential of the model in studies of the pathogenesis of infections and virulence of bacteria of the oviduct.

AB - Salpingitis and peritonitis are common pathological manifestations observed in egg-laying hens. To improve methods to study these conditions, a surgical model was developed. Initially, eighteen white layers underwent laparotomy with subsequent inoculation of ink, bacteria or sterile broth directly into the oviduct. Eight birds inoculated with 0.1 ml blue ink were euthanized immediately after inoculation and the specific site of inoculation was assessed. In all birds, ink was injected into the oviduct between five and seven cm cranial to the isthmus. To demonstrate the use of this approach to cause infection of the oviduct, five birds were inoculated with 8.6 × 10(6)CFU of a clinical Escherichia coli isolate. Five control birds received broth with no bacteria. Both infected and control birds were euthanized after 48 h followed by a post mortem examination. Infected birds showed diffuse fibrino-purulent peritonitis, E. coli was found in pure culture from one or more positions in the oviduct and the liver. Birds receiving sterile broth did not culture positive and demonstrated no gross lesions. Subsequently, 19 birds were inoculated with an isolate of E. coli ST95 and 20 birds with an isolate of E. coli ST141. Major variation in virulence was observed between the two isolates used in relation to clinical signs, gross lesions and histopathology. In contrast to E. coli ST141, E. coli ST95 caused severe clinical signs, epithelial necrosis of the oviduct and purulent salpingitis. The results of the study show the potential of the model in studies of the pathogenesis of infections and virulence of bacteria of the oviduct.

KW - Animals

KW - Bacterial Load

KW - Chickens

KW - Escherichia coli

KW - Escherichia coli Infections

KW - Female

KW - Oviducts

KW - Poultry Diseases

KW - Species Specificity

KW - Faculty of Health and Medical Sciences

KW - Egg-laying hens

KW - Infection model

KW - Salpingitis-peritonitis

KW - Escherichia coli

KW - Virulence

U2 - 10.1016/j.vetmic.2014.02.043

DO - 10.1016/j.vetmic.2014.02.043

M3 - Journal article

C2 - 24703749

VL - 170

SP - 368

EP - 374

JO - Veterinary Microbiology

JF - Veterinary Microbiology

SN - 0378-1135

IS - 3-4

ER -