Oviduct infection (salpingitis) is the most common infection in egg laying hens and mainly caused by Escherichia coli. The infection may transmit pathogenic E. coli horizontally and vertically. The clinical manifestations of salpingitis may be grouped into acute, chronic and subclinical. It has not yet been clarified whether these clinical manifestations are due to characteristics of the E. coli or whether factors as host immunity and infectious dose are determining factors.
The aim of this study was to investigate whether different genotypes of E. coli are associated with clinical and pathological outcomes of acute, chronic or subclinical salpingitis.
Hens with salpingitis from 14 flocks of egg laying hens (4 broiler breeders, 4 organic layers, 4 barn housed layers and 2 layers in furnished cages) were included. For detection of acute and chronic cases of salpingitis broiler breeders were followed for a full production period where 10 dead hens/week/flock were collected. To detect subclinical salpingitis, 500 randomly selected apparently healthy layers/flock were collected at the end of production.
E. coli from salpingitis of broiler breeders and layers (178 and 52 isolates, respectively) were typed by pulsed-field-gel-electrophoresis (PFGE) for selection of non-clonal isolates for whole genome sequencing (WGS). From acute, chronic and subclinical salpingitis, 33, 30 and 42 E. coli isolates, respectively were selected for WGS so all farm types and all PFGE clones were represented.
The five most prevalent sequence types of E. coli were: 95, 117, 140, 131 and 428 which are well known in poultry. Phylogenetic analysis of the accessory genome showed a random clustering of E. coli isolated from acute, chronic and subclinical salpingitis.
Based on the analysis we did not find any clear association between genotype of E. coli and clinical and pathological manifestation of acute, chronic or subclinical salpingitis in egg laying hens.