An Examination Of Diversity Of Flavobacterium psychrophilum Isolates From Different Origins And A Note On A Medium Used To Recover Isolates From Long-Term Frozen Storage     Clifford E. Starliper1 and Richard K. Cooper2   1USGS, National Fish Health Research Laboratory, 11700 Leetown Road, Leetown WV; 2Department of Veterinary Science, Louisiana State University, Baton Rouge, LA.     About 150 isolates of Flavobacterium psychrophilum were collected in 1996 from five geographic origins and examined for similarities/diversity by comparing plasmids and restriction enzyme profiles on 16s rRna PCR products. Three origins (QC, QN, HT) were from Washington State and two were from the Eastern U.S., West Virginia and Pennsylvania. Western hosts were Coho salmon and steelhead trout; eastern hosts were rainbow and golden trout. Within and between site diversity, as well as comparisons of Eastern vs. Western and host vs. host were examined. Clinical signs in the populations from the three locations in Washington State and the one from WV included external body surface lesions, internal tissues involvement with chronic to acute mortality. Clinical signs in rainbows from PA differed; at first observation the signs could be confused with those of Whirling Disease. Flavobacterium psychrophilum was isolated from external lesions and from internal tissues of fish from all five origins. Primary isolation was on Cytophaga agar and isolates were frozen in fresh Cytophaga broth. Upon recovery after 6 years in storage, none (0%) re-grew in Cytophaga broth, however, 93.3% did using the following medium (formulated from four literature citations): 0.5% tryptone, 0.05% yeast extract, 0.028% sodium acetate-3H2O, 0.05% beef extract, 0.02% calcium chloride, 0.074% magnesium sulfate-7H2O, and 5% fetal bovine serum.