Comparison of the Utility of dnaJ and 16S rDNA Sequences for Identification of Clinical Isolates of Vibrio Species

ABSTRACT

BACKGROUND: Among the many Vibrio species that can cause infections in humans, several species can cause a fatal outcome. Therefore, accurate identification of Vibrio species is very important. Since some species show atypical phenotypic features, selecting an appropriate molecular method is necessary to avoid misdiagnosis. METHODS: Vibrio clinical isolates (N=53) and reference strains (N=8) were used in this study. We analyzed the following sequences for identification dnaJ gene, 16S rDNA, gyrase B (gyrB) V. vulnificus-specific sequence, gyrB V. navarrensis-specific sequence, and V. vulnificus hemolysin gene PCR (Vvh PCR). We performed phylogenetic analysis of the 16S rDNA, dnaJ, and gyrB sequences. Final identification was based on the combined results of all tests described above. Concordance of the 16S rDNA and dnaJ sequence analysis was measured using the Chi-square test. RESULTS: The 61 Vibrio strains were identified as follows, in descending order V. vulnificus (78.69%), V. parahaemolyticus (6.56%), V. navarrensis (4.92%), V. mimicus (1.64%), V. cholera (1.64%), V. furnissii (1.64%), V. alginolyticus (1.64%), and Grimontia hollisae (1.64%). The accuracy rates of the dnaJ gene and 16S rDNA sequence for identification were 91.80% and 86.89%, respectively. The 16S rDNA and dnaJ sequences showed a concordance rate of 0.45, which indicates moderate agreement. CONCLUSIONS: Our results suggest that analysis of the dnaJ sequence may be a useful method for the identification of clinical isolates of Vibrio species, especially for distinguishing between closely related Vibrio species.