Culture-independent identification of bacteria associated with ovine 'broken mouth' periodontitis

'Broken mouth' periodontitis (BMP) is a painful condition of sheep grazed on rough pasture and involves periodontal infection of the incisor teeth and progressive tooth loss. This can reduce the efficiency of grazing of sheep, which contributes to malnutrition, weight loss, systemic health problems, poor quality of life and early culling from flocks. Consequently, this condition is a major economic problem to sheep farmers. However, there are no treatment or control methods available. The aim of this study was to identify the bacteria associated with BMP and oral health in sheep. Swabs were collected from the gingival pockets of three sheep with BMP and from the gingival margin of three orally healthy (normal) sheep. Bacteria were identified using culture-independent (16S rRNA gene sequencing) methods. In the normal samples, 26 phylotypes were identified. The most prevalent species were Enterobacter hormaechei (21.3% of analysed clones) and Hafnia alvei (21.3%), with uncultured (4.4%) and novel (5.0%) phylotypes also being identified. For the BMP samples, 24 phylotypes were identified. The most prevalent species were Mannheimia ruminalis (28.4%) and Moraxella caprae (13.5%), with uncultured (2.6%) and novel (24.5%) phylotypes also being identified. In conclusion, a distinct microflora is associated with BMP and oral health in sheep and M. ruminalis may be involved in the aetiology of BMP.