A selective procedure for the field isolation of pathogenic Streptococcus spp. of rainbow trout (Salmo gairdneri)

A procedure established for the selective isolation of the species of Streptococcus responsible for rainbow trout streptococcosis in South Africa, consisted of the inoculation of samples into nutrient broth which had been supplemented with 100 micrograms/ml of nalidixic acid, 160 micrograms/ml of ox...

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Bibliographic Details
Published inOnderstepoort journal of veterinary research Vol. 56; no. 3; p. 179
Main Authors Bragg, R R, Todd, J M, Lordan, S M, Combrink, M E
Format Journal Article
LanguageEnglish
Published South Africa 01.09.1989
Subjects
Animals
Bacteriological Techniques
Culture Media - standards
Salmonidae - microbiology
Streptococcus - isolation & purification
Trout - microbiology
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Summary:A procedure established for the selective isolation of the species of Streptococcus responsible for rainbow trout streptococcosis in South Africa, consisted of the inoculation of samples into nutrient broth which had been supplemented with 100 micrograms/ml of nalidixic acid, 160 micrograms/ml of oxolinic acid or 200 micrograms/ml of sodium azide. After incubation, the sample was plated onto tetrazolium agar on which the rainbow trout pathogenic Streptococcus species grew as a red colony. The colonies were isolated from the tetrazolium agar and identified as rainbow trout pathogenic isolates by biochemical and serological tests. In the laboratory the selective procedure is capable of detecting about 2 bacteria per ml. This procedure was used in the field and biochemically identical Streptococcus species were found in the mud and a freshwater crab from the water source of a site with a history of streptococcosis.
ISSN:0030-2465