First isolation of Photobacterium damselae subsp. damselae from half-smooth tongue sole suffering from skin-ulceration disease

• Published in: Aquaculture Vol. 511; p. 734208
• Main Authors: Shao, Peng, Yong, Pengzheng, Zhou, Wenli, Sun, Jinhui, Wang, Yizhe, Tang, Qingping, Ren, Shutian, Wu, Zun, Zhao, Chongyang, Xu, Yuanfei, Wang, Xiaoyu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2019
• Subjects: Antimicrobial resistance; Bacteria; Cynoglossus semilaevis; Histopathology; Photobacterium damselae subsp. damselae; Ulceration; Histopathology; H&E; TCBS; Bacteria; Photobacterium damselae subsp. damselae; Cynoglossus semilaevis; Antimicrobial resistance; Ulceration; PCR
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2019.734208

Climate change will likely promote the emergence of the mesophilic bacteria Photobacterium damselae subsp. damselae as a pathogen affecting global economic marine fish farming. In this study, we identified links between P. damselae subsp. damselae and skin ulcerations in commercially farmed half-smooth tongue sole (Cynoglossus semilaevis) in the Bohai Bay area. Nearly circular ulcerations appeared on the pigmented side of the diseased fish and were caused by damage to the epidermis, dermis, and muscular layers, with significant congestion found in the brain, liver, and intestine accompanied by significant pathological changes. Physiological and biochemical characterization and 16S rRNA gene sequencing identified six kinds of bacteria isolated from diseased fish, with artificial-infection testing and histopathologic analysis revealing P. damselae subsp. damselae as the cause of death and the variable clinical symptoms (abdominal swelling and skin ulcers) observed following injection with different concentrations of bacterial suspension (~104–106 CFU mL−1). Additionally, histological analysis showed that the pathological changes induced by the bacterial suspensions were similar to those found in naturally diseased fish; however, the degree of damage differed according to time after infection. Moreover, antimicrobial-susceptibility testing showed that P. damselae subsp. damselae exhibited different degrees of resistance to 11 of 13 types of antibacterial drugs but strong susceptibility to chloramphenicols, suggesting their efficacy for first-line treatment of diseased fish. •P. damselae subsp. damselae is the pathogen of half-smooth tongue sole ulcer disease in the Bohai Bay area.•This study shows that the strain exhibit different degrees of resistance to 11 of 13 types of antibacterial drugs.•P. damselae subsp. damselae may damage muscle tissues and cause obvious pathological changes in the brain of diseased fish.