New selective plating medium for isolation of Vibrio vulnificus biogroup 1

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Abstract
A new plating medium (VV agar) was developed as an alternative to thiosulfate-citrate-bile salts-sucrose (TCBS) agar for the isolation of V. vulnificus. Salicin (2% wt/vol) was used as the carbohydrate source with potassium tellurite (0.0005% wt/vol), crystal violet (0.00015% wt/vol), oxgall (0.8% wt/vol) and a pH of 8.6 used to inhibit growth of gram-positive and gram-negative organisms other than V. vulnificus. Because strains of V. vulnificus do not strongly ferment salicin in VV agar, a pH indicator was not included in the medium. Growth of V. vulnificus appeared on VV agar as large grey colonies with black centers. Other non-Vibrio strains which grew on the medium produced smaller colonies and failed to take up tellurite. VV agar was more effective than TCBS agar in inhibiting members of the Enterobacteriaceae and gram-positive cocci. Only Vibrio strains capable of utilizing salicin grew well on VV agar. Recovery and growth of V. vulnificus were superior on VV agar, compared with TCBS agar.