Mixed infection in columnaris disease of fish

In addition to Flexibacter columnaris, Corynebacterium sp was recovered from lesions associated with columnaris disease in catfish. Catfish exposed to pure cultures of the Corynebacterium sp developed circumscribed lesions, which regressed without further adverse effects. Disease signs were not demonstrable in catfish exposed to pure cultures of F columnaris; however, when catfish were exposed to mixed cultures of th Corynebacterium sp and F columnaris, signs of columnaris appeared and the fish died.