Fusobacterium necrophorum is a pathogen of humans and animals, and in sheep is associated with footrot which has significance for welfare and productivity of sheep flocks worldwide. F. necrophorum is believed to be an opportunistic pathogen in footrot, and the mouths of sheep have been suggested as a reservoir site. The aim of this study was to compare communities of F. necrophorum present on the feet and in the mouths of sheep.
A multiple locus variable number tandem repeat analysis (MLVA) community typing scheme for F. necrophorum was used to analyse DNA extracted from 33 mouth swabs and 49 foot swabs collected from sheep on 6 farms in England. Farm A was a longitudinal study of 10 sheep sampled on 4 occasions at 2 week intervals. On Farms B-F, 15 sheep were sampled on one occasion.
MLVA typing was successful for 28/33 mouth and 32/49 foot swabs. There were four strains of F. necrophorum detected on feet, and single strain communities of F. necrophorum were detected from 31/32 foot swabs. There were 16 different community types identified from 28 mouth swabs and 18/28 mouth swabs contained multiple strains of F. necrophorum. There were between 2 and 8 strains of F. necrophorum in multi-strain communities. On farms where MLVA profiles were available for both foot and mouth swabs, the strain(s) present on feet were found in mouths, but the majority of strains present in mouths were never detected on feet.
This is the first study of communities of F. necrophorum in sheep and the results reveal key differences between strains present on feet and in mouths. The findings suggest that a diverse community of F. necrophorum is present in the mouths of sheep, and that a subset of strains from this community have adapted to grow on feet.