Low incidence of Vibrio vulnificus among Vibrio isolates from sea water and shellfish of the western Mediterranean coast

A specific search for Vibrio vulnificus in natural marine samples from the Spanish Mediterranean Sea was carried out by nested PCR and cultural approa ches using thiosulphate-citrate-bile salts-sucrose agar (TCBS) and cellobio se-polymixin B-colistin agar (CPC), incubated at 40 degrees C, as selective media, Presumptive colonies were identified by PCR using specific primers against 23S rRNA sequences. This species was isolated from sea water and ed ible bivalves, mainly after preenrichment in alkaline peptone water (APW) a t 40 degrees C followed by CPC agar. None of the V, vulnificus isolates ide ntified corresponded to serovar E, Dominant Vibrio species on directly inoc ulated TCBS plates incubated at 25 degrees C were V. splendidus below 20 de grees C and V, harveyi and V. mediterranei above that temperature. Low perc entages of several pathogenic vibrios were recorded but V. vulnificus was n ever recovered at this incubation temperature. The incidence of this specie s in the samples studied was lower than that described for other geographic al areas, probably due to the high salinity values of the Mediterranean Sea .