First reports of flexibacteriosis in farmed tub gurnard (Chelidonichthys lucerna L.) and wild turbot (Scophthalmus maximus) in Italy.

Two episodes of flexibacteriosis caused by T. maritimum were diagnosed in wild turbot and farmed tub gurnard in Italy. The two different cases occurred in the facilities of Universtiy of Camerino during reproduction trials. A group of 10 adult turbot showed haemorrhagic, frayed fins and eroded mouth two weeks after capture from the North Adriatic Sea. The disease was controlled by antibiotic therapy. A group of 20 tub gurnard showed eroded mouth, rotten fins and severe skin ulcerative lesions, after 3 days of transportations from a fish farm to our laboratory facilities. Mortality reached 90% of the population within 9 days. Traditional bacteriological and PCR analysis of the isolates in the two episodes allowed the identification of the causative agent as Tenacibaculum maritimum. Serological characterization of the isolates demonstrated that they belonged to serotype O3. Histopathological examination showed severe skin necrosis, dermis congestion associated with heterophilic and macrophagic infiltration. Immunohistochemical analysis of skin tissue, using specific polyclonal antibody against T. maritimum serotype O3, allowed the visualisation of positive stained macrophages. These cases, which constitute the first descriptions of flexibacterioris in cultured tub gurnard and wild turbot in Italy, leads to consider T. maritimum as a potential risk for the future Italian culture of these two fish species.