Pathology of Enterococcus sp. infection in farmed turbot, Scophthalmus maximus L.

Abstract The lesions of an enterococcal septicaemia occurring in turbot, Scophthalmus maximus (L.), cultured in several farms in northwest Spain are described. The agent of this septicaemia was identified previously as an Enterococcus -like bacterium. Two main patterns of lesions were observed in the diseased turbot: a focal form characterized by exophthalmia, muscular haemorrhages, acute branchitis, and suppurative inflammation of periorbital tissues, eyeball, meninges and brain; and another generalized form with similar lesions, but showing more extensive haemorrhages, ulceration and purulent inflammation of the skin, desquamative enteritis, and necrosis of spleen and kidney. Fatty changes of the liver were observed in all turbot examined (diseased and controls), which indicates that these alterations were not related to the infection. Experimentally inoculated turbot developed lesions corresponding to the generalized form of the natural disease. Although the Enterococcus strain was recovered in pure culture from all the organs, Gram-positive bacteria could not be visualized histologically in the lesions of muscle and brain.