Lethal cold stress of Vibrio vulnificus in oysters.

Studies were conducted on the survival of Vibrio vulnificus, an estuarine human pathogen, in oyster homogenates held at 4 degrees C. Results indicated a rapid and dramatic decrease in viability not attributable to either cold shock or the oyster homogenate alone but to a combination of the two. Such a decline was not observed with Vibrio parahaemolyticus. Chilled V. vulnificus cells were unable to repair themselves in brain heart infusion broth at 37 degrees C. V. vulnificus cells incubated on whole raw oysters at 0.5 degrees C also exhibited a decline in viability, but of a lesser degree. The effects of various plating media were also investigated. The data reported here suggest that oysters kept on ice are not likely to be a major factor in the epidemiology of V. vulnificus infection. It is further suggested that the standard method of homogenizing oysters for examining bacteriological quality should not be followed because toxic compounds are released from the oysters during this process.