Characterization of prevalent bacterial pathogens associated with pododermatitis in table egg layers.

Pododermatitis has been observed in several layer flocks in Denmark during 2015. The aetiology is complex, including litter quality, nutrition and management. Bacterial pathogens associated with pododermatitis, however, have not received much attention. The aim of the present study was, therefore, to identify 106 bacterial isolates obtained from pododermatitis in table egg layers in addition to five isolates from spleen/bursa presternalis. Isolates were obtained from layers from six affected flocks. All isolates were identified by standard bacterial methods, species-specific PCRs, 16S rRNA sequencing or matrix-assisted laser desorption-ionization identification. Staphylococcus aureus and Enterococcus faecalis made up 75/111 (68%) and 15/111 (14%) of the isolates from pododermatitis, respectively; the remaining isolates represented Escherichia coli (10), Staphylococcus hyicus (5), Gallibacterium anatis (3), Trueperella pyogenes (2) and Aerococcus urinaeequi (1). All isolates of S. aureus were spa-typed. Spa-type t8646 and t002 made up 72% and 26% of the S. aureus isolates, respectively. The same types were also demonstrated from spleen/bursa presternalis. The same or closely related spa-types were found among 6/11 sepsis-affected day-old chicks included for comparison, indicating that these types of S. aureus are ubiquitous pathogens in poultry. In contrast, isolates of E. faecalis and E. coli showed major population diversity. In conclusion, the results suggest that S. aureus is a major pathogen associated with pododermatitis abscesses, which could be from a common source, whereas the diversity among the E. faecalis and E. coli populations suggests that these bacteria might originate from multiple sources.