Evaluation Of Commercially Prepared Transport Systems For Non-Lethal Detection Of Aeromonas salmonicida In Salmonid Fish   Rocco C. Cipriano1 and Graham L. Bullock2   1National Fish Health Research Laboratory, United States Geological Survey/Biological Resources Division, 1700 Leetown Road, Kearneysville, West Virginia 25430, U.S.A.; 2Freshwater Institute, The Conservation Fund, Post Office Box 1889, Shepherdstown, West Virginia 25443, U.S.A.   In vitro studies indicated that commercially prepared transport systems containing Amies, Stuart’s, and Cary-Blair media worked equally well in sustaining the viability of the fish pathogen Aeromonas salmonicida, cause of furunculosis.  The bacterium remained viable without significant increase or decrease in cell numbers for up to 48 hours of incubation at 18-20oC in Stuart’s Transport Medium and, consequently, obtaining mucus samples in such tubes were compared to on-site detection of A.salmonicida  by dilution plate counts on Coomassie Brilliant Blue Agar.  In three different assays of 100 samples of mucus from Atlantic salmon (Salmo salar) infected subclinically with A. salmonicida, dilution counts conducted on-site proved more reliable to detect the pathogen than obtaining the samples in the transport system.  In such assays, dilution counts detected the pathogen in 34, 41, and 22 samples whereas this  was accomplished in only 15, 15, and 3 of the respective samples when the transport system was used.  In an additional experiment, Arctic char (Salvelinus alpinus) sustaining a frank epizootic of furunculosis were sampled similarly.  Here, too, dilution counts were more predictive of the prevalence of A. salmonicida  and detected the pathogen in 46 mucus samples.  By comparison,  only 6 samples collected by using the transport system were positive.  It was also observed that the transport system supported the growth of the normal mucus bacterial flora.  Particularly  predominant among these were motile aeromonads and Pseudomas fluorescens.  In mixed culture growth studies,  two representatives of both of the latter genera of bacteria outgrew A. salmonicida and, in some cases, to the total exclusion of the pathogen, itself.