28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Survey Of Bacteria Isolated From Catfish, Salmon, Tilapia And Trout Fillets David C. Melka1, Ron A. Miller1, and Renate Reimschuessel1 1Food and Drug Administration – Center for Veterinary Medicine, Office of Research, Division of Animal and Food Microbiology, 8401 Muirkirk Rd. Laurel, MD 20708 Little information is available about the microbial populations of aquaculture products to which the consumer is exposed.   Recently, the Food and Drug Administration’s (FDA) Center for Veterinary Medicine conducted a survey to identify microorganisms readily cultured from cultured finfish fillets.  We tested 52 catfish, 29 Atlantic salmon, 24 rainbow trout, and 23 tilapia fillets purchased from markets in the Washington D.C. area.  Fillets were cultured by swabbing a 10 cm 2 area on each fillet and inoculating 5ml of 0.85% saline.  Suspensions were plated on TSA2 with 5% sheep blood agar and incubated at 22°C and, 30 or 35 ºC.  Up to five bacterial colonies with differing morphologies were selected from each plate for subsequent identification.  Isolates were run on API 20E, 20NE, 20 STREP and STAPH strips (bioMeieux, France), the automated Vitek ® (bioMeieux, France), and whole cell fatty acid methyl ester (FAME) analysis (MIDI Inc, Newark, DE).  The identification was deemed final when the results from two differing systems concurred.  Using this criterion, the identity of 186 organisms was confirmed. Channel catfish and tilapia fillets yielded Acinetobacter, Aeromonas, Staphylococcus, Streptococcus species and a number of species of the Enterobacteriaceae not yet identified.  Catfish fillets also harbored: Ewingella americana, Hafnia alvei, Klebsiella spp., Serratia spp., and Enterococcus.  Salmon fillets yielded:  Klebsiella pneumoniae ozaenae, Serratia liquefaciens, Staphylococcus sciuri and Staphylococus warneri.  Pseudomonas species were found on all the different types of fish fillets.  This survey provided insight into the bacteria commonly found on cultured fish fillets to which the consumer will be exposed. Future studies will examine the antimicrobial susceptibility of selected isolates, to determine if some of the microflora can be used as marker organisms for changes in antimicrobial susceptibility within the aquaculture environment. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page