Example of a drug sensitivity test for florfenicol. Two small disks with drug were placed onto an agar plate inoculated with bacterium. The wider the distance from disk to bacterial growth, the more effective the drug.

Eric Leis and Becky Lasee of the La Crosse Fish Health Center, U.S. Fish and Wildlife Service and Mark Gaikowski and Sue Schleis, Upper Midwest Environmental Sciences Center, U.S. Geological Survey submitted the following completion report to Schering-Plough Animal Health Corporation:  Gaikowski, M.P., Schleis, S.M., Lasee, B.A. and E. Leis.  Field effectiveness of AquaflorTM (50% Type Medicated Article), Florfenicol - SCH25298 administration in feed to control mortality associated with Streptococcus iniae in tilapia (Oreochromis spp.), 355 pages.  The Fish Health Center was responsible for isolation and confirmation of the Streptococcus bacterium in tilapia reared at the Minaqua Fisheries facitlity in Renville, MN.  Drug sensitivities of isolated colonies to the florfenicol drug were also performed at the Center.  Field studies, like this one, support the Federal Drug Administration (FDA) approval of new drugs for treating serious diseases of propagated fish.