Effect of temperature and salinity on Vibrio (Beneckea) vulnificus occurrence in a Gulf Coast environment

Vibrio (Beneckea) vulnificus is a recently recognized halophilic organism that may cause serious human infections. Patients infected with V. vulnificus often have a history of exposure to the sea, suggesting that the organism may be a common inhabitant of marine environments. Twenty-one inshore sites around Galveston Island in the Gulf of Mexico were cultured for V. vulnificus over a 12-month period. The organism was recovered from all but one of the sites at some time during the study. It was frequently isolated during the summer and fall from environments of relatively low salinity (7 to 16%). V. vulnificus was rarely isolated from any of the sites during the winter months, when water temperatures dropped below 20 degrees C. In vitro growth characteristics of environmental isolates of V. vulnificus demonstrated salinity optima of 1.0 to 2.0% NaCl and a temperature optimum of 37 degrees C. These growth characteristics may account for the seasonal and geographical variations in occurrence of the organism. Overall, the results of these studies indicate that V. vulnificus is commonly found in Gulf Coast environments and that the occurrence of the organism is favored by warm temperatures and relatively low salinity.