Isolation and Characterization of Kocuria rhizophila as emerging opportunist pathogen in rainbow trout (Oncorhynchus mykiss)

Rainbow trout as an important commercial fish has been exposed to a phylogenetically diverse group of bacterial pathogens. A farm in Amol reported heavy mortalities of rainbow trout (Onchorhinchus mykiss). The current study aimed to identify the etiological agent responsible for that. The moribund and freshly dead fish were analyzed for clinical changes. Biochemical and molecular characterizations were performed to identify the etiological agents of the disease. The results of the biochemical tests and Polymerase chain reaction (PCR) assay confirmed that Kocuria rhizophila was responsible for the disease severity. These findings indicate that the disease outbreak in rainbow trout farm occurred as a result of Kocuria rhizophila. Proper understandings about the new etiological agents and the relationship of stress-related environmental component are necessary for effective management and control of diseases.