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Title: A TRANSPORT SYSTEM FOR THE MAINTENANCE OF VIABILITY OF ACINETOBACTER CALCOACETICUS, STREPTOCOCCUS INIAE, AND S. AGALACTIAE OVER VARYING TIME PERIODS

Author
item Evans, Joyce
item Wiedenmayer, Alyssa
item Klesius, Phillip

Submitted to: European Association of Fish Pathologists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2002
Publication Date: 8/1/2002
Citation: EVANS, J.J., WIEDENMAYER, A.A., KLESIUS, P.H. A TRANSPORT SYSTEM FOR THE MAINTENANCE OF VIABILITY OF ACINETOBACTER CALCOACETICUS, STREPTOCOCCUS INIAE, AND S. AGALACTIAE OVER VARYING TIME PERIODS. EUROPEAN ASSOCIATION OF FISH PATHOLOGISTS. 22(4):238-246. 2002.

Interpretive Summary: Field sampling of microbiological flora from fish for research or diagnostic purposes necessitates an effective method for the collection and transport and maintenance of bacterial specimens during transport periods. Fish mortality events occur worldwide, sometimes in remote sites where necessary laboratory facilities, equipment or personnel are unavailable. A system capable of maintaining survival of bacterial cultures over an extended period of time is crucial in instances when samples need to be shipped to a designated laboratory for analysis. It is also necessary to know the amount of time a sample remains usable from the time it is acquired. Two species of Gram positive cocci, Streptococcus iniae and S. agalactiae have been identified in recent years as emerging fish pathogens in both freshwater and marine environments. We evaluated the utility of Stuart's media transport swabs in maintaining bacteria for up to 10 days. Transport swab media ampules were either broken or unbroken for each bacterial species and time period (4, 5, 7 and 10 days) to determine the optimal conditions of transport. Our results indicate that transport swabs with broken media ampules optimize conditions for the growth of Gram negative bacterial species and unbroken media ampules optimize conditions for the viability of Gram positive species. Under these conditions, bacteria remain viable for 10 days. Field investigations and collections of microbial samples should include a consideration of sampling methodology, transport time and target organisms to aid in identification of bacterial species.

Technical Abstract: We evaluated the utility of Bacti-Swab NPG Modified Stuart's medium (Remel)in maintaining viable Gram negative (Acinetobacter calcoaceticus) and Gram positive bacteria (Streptococcus iniae and S. agalactiae) for up to 10 days. In the first experiment, qualitative assessment of the viability of S. iniae, S. agalactiae, and A. calcoaceticus swabbed from cultures was determined in vitro. In the second experiment, quantitative assessment of the viability of S. agalactiae was determined from swab cultures following intraperitoneal inoculation of Nile tilapia (Oreochromis niloticus) and re-isolation of the bacterium from brain, kidney, and intestine of diseased fish. Transport swab media ampules were either broken or unbroken for each bacterial species and time period (4, 5, 7, and 10 days) to determine the optimal conditions of transport. Our results indicate that transport swabs with broken media ampules optimize conditions for the viability of Gram negative bacterial species and unbroken media ampules optimize conditions for the viability of both Gram positive and negative bacterial species. Under these conditions, bacteria remain viable for 10 days. Media appears to be unnecessary for maintaining bacterial viability, particularly for Gram positive bacterial species. Field investigations involving collections of microbial samples should include consideration of sampling methodology, transport time, and target organisms.