A non-destructive method for rapid detection of Tenacibaculum maritimum in farmed fish using nested PCR amplification

Marine tenacibaculosis caused by Tenacibaculum maritimum is an important disease in different cultured marine fish. Some of the presently available techniques for the detection of T. maritimum are either time consuming or lack sufficient sensitivity. In this study, we evaluated the efficacy of a nested PCR method for the detection of T. maritimum using non-destructive mucus samples from different cultured species of marine fish. To test this method sixty asymptomatic and symptomatic cultured fish were examined. The nested PCR assay allowed the detection of T. maritimum in 100% of mucus samples from farmed turbot, sole and gilthead seabream that were undergoing an epizootic of tenacibaculosis. Only 81% of the mucus samples from these diseased fish were positive by plating methods. When the nested PCR protocol was applied to different mucus samples obtained from apparently healthy fish, the detection of T. maritimum was positive in 15 of 29 fish tested. Nine of these fish had been diagnosed as negative for the presence of T. maritimum by cultivation on agar. The method presented here demonstrated that non-lethal mucus samples can be used with screening purpose and early diagnosis of marine tenacibaculosis, allowing the rapid detection of T. maritimum (in only 7 h) without previous isolation in culture media.