First isolation of Carnobacterium maltaromaticum from farmed rainbow trout Oncorhynchus mykiss in Virginia.

Carnobacterium maltaromaticum is considered an emerging pathogen of salmonids in the United States and around the world. Bacterial cultures obtained from the posterior kidney and skin of moribund rainbow trout Oncorhynchus mykiss from a commercial aquaculture facility in Virginia, USA grew C. maltaromaticum, which was confirmed by additional phenotypic and molecular characterization. A presumptive diagnosis based on the clinical signs, necropsy observations, histopathology and bacterial cultures was bacterial septicemia due to C. maltaromaticum. This represents the first documentation of C. maltaromaticum in rainbow trout from Virginia.