Vibrio tapetis is the marine bacterium responsible for the brown ring disease (BRD) affecting die manila clam, Ruditapes philippinarum. Identification of V tapelis has been previously performed using biochemical criteria and serological procedures. All of these methods are time consuming and ill-adapted to individual screening. This study describes an oligonucleotidic probe (Vt446) and two PCR primers, deduced from the 16S rDNA sequence, allowing a fast and specific V tapetis identification using dot blot hybridisation and species-specific primed PCR (SSP-PCR). The probe and primers have been tested on 60 strains, including referenced Vibrio sp., Gram negative and positive bacteria, marine bacteria samples and isolated clam bacteria. For all the 19 V tapetis strains, the results of PCR assays consistently corroborated those of the agglutination tests. The detection limit was estimated to be 10(2) CFU ml(-1). The SSP-PCR method has resulted in V tapetis detection in larvae, m diseased clams, and in asymptomatic broodstock clams that later developed BRD. In conclusion, the two SSP-PCR primers were useful for direct and fast identification of V tapetis strains isolated in clams, and are well suited for the screening of individual R. philippilnarum broodstock clams and larvae from the hatchery. (C) 2005 Elsevier B.V. All rights reserved.