Comparison of different biochemical and molecular methods for the identification of Vibrio parahaemolyticus

Abstract

Aims: Multicentre evaluation of biochemical and molecular methods for the identification of Vibrio parahaemolyticus. Methods and Results: For the biochemical identification methods, API 20E and API 20NE and Alsina's scheme were evaluated in intra‐ and interlaboratory tests in order to determine the accuracy and concordance of each method. Both in intra‐ and interlaboratory tests, the Alsina's scheme showed the highest sensitivity (86% of correct identifications in the interlaboratory test). False‐positive results were obtained by all methods (specificity was 95% for API 20E, 73% for API 20NE and 84% for Alsina's scheme) and concordance varied from 65% of API 20NE to 84% of API 20E. For the molecular identifications, polymerase chain reaction (PCR) for the detection of toxR gene, tl gene and pR72H fragment were tested on 30 strains by two laboratories. The PCR for toxR showed the highest inclusivity (96%), exclusivity (100%) and concordance (97%). Conclusions: Among the biochemical identification methods tested, the Alsina's scheme gave more reliable results; however, in order to avoid false‐positive results, all the biochemical identifications should be confirmed by means of molecular methods. Significance and Impact of the Study: Availability of an efficient identification method of Vibrio parahaemolyticus to use in official control of fisheries products.

Biochemical, Serological, and Virulence Characterization of Clinical and Oyster Vibrio parahaemolyticus Isolates

“…Our sample selection criteria, including preferential selection of tdh-negative, trh-negative strains from oysters, introduces a possibility of sample selection bias in the statistical comparisons, but the relative proportions of strains negative for both tdh and trh in the two groups of isolates, clinical and oyster, were similar. As in previous reports, the API 20E test was unreliable for the identification of the V. parahaemolyticus isolates (8,21), but all strains were identified by the presence of the V. parahaemolyticus species-specific tlh gene. The only novel trait observed in this set of isolates was the ability to produce ␤-galactosidase (ONPG test), but this was not a differential feature between clinical and oyster isolates.…”

“…Even so, V. parahaemolyticus illnesses are believed to be highly underdiagnosed (143-fold), possibly due to the relatively low hospitalization (22.5%) and fatality (0.9%) rates (36). Another factor that may influence the underdiagnosis is the fact that traditional biochemical identification of V. parahaemolyticus has proven less reliable than molecular identification for clinical and food isolates (8,21). When an isolate is confirmed as V. parahaemolyticus, virulence characterization is typically performed.…”

Genes Similar to the Vibrio parahaemolyticus Virulence-Related Genes tdh , tlh , and vscC2 Occur in Other Vibrionaceae Species Isolated from a Pristine Estuary

“…The mol% GϩC content of tlh (47.6%) (13) corresponds to the mol% GϩC contents of these four Vibrionaceae species (43 to 49%) (42), which indicates that any horizontal transfer of tlh within this family occurred far enough in the past for genetic drift to eliminate clear-cut evidence of this process. Some previous reports of tlh in non-V. parahaemolyticus vibrios attributed its detection to false-positive results (47). False-positive PCR amplifi- cation arising from sample contamination is certainly possible, but true tlh amplicons may have been recovered instead.…”

FORMAÇÃO DE BIOFILME APÓS ESTRESSE SUBLETAL POR Vibrio parahaemolyticus ISOLADOS DE CAMARÃO-ROSA (Farfantepenaeus paulensis)

“…Este gene possui um fragmento de 368 pares de base (pdb) específico para Vibrio parahaemolyticus que é encontrado em todos os isolados (13) . O uso deste gene para identificação de V. parahaemolyticus através da reação em cadeia da polimerase (PCR) é específico, sensível e rápido (9,13,14) , pois, além de V. parahaemolyticus ser detectado em todas as amostras analisadas, não ocorrem resultados falsos positivos (10,15) . Biofilme bacteriano é uma comunidade de micro-organismos sésseis que são capazes de se agregar e aderir a uma superfície, embebidos em uma matriz extracelular formada por exopolissacarídeos (16) .…”