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. 2014 Sep-Oct;56(5):427-32.
doi: 10.1590/s0036-46652014000500010.

Detection of virulence genes in environmental strains of Vibrio cholerae from estuaries in northeastern Brazil

Francisca Gleire Rodrigues de Menezes  1 , Soraya da Silva Neves  1 , Oscarina Viana de Sousa  2 , Candida Machado Vieira Maia Vila-Nova  2 , Rodrigo Maggioni  2 , Grace Nazareth Diogo Theophilo  3 , Ernesto Hofer  3 , Regine Helena Silva dos Fernandes Vieira  2
Affiliations

Detection of virulence genes in environmental strains of Vibrio cholerae from estuaries in northeastern Brazil

Francisca Gleire Rodrigues de Menezes et al. Rev Inst Med Trop Sao Paulo. 2014 Sep-Oct.

Abstract
in English, Portuguese

The objectives of this study were to detect the presence of Vibrio cholerae in tropical estuaries (Northeastern Brazil) and to search for virulence factors in the environmental isolates. Water and sediment samples were inoculated onto a vibrio-selective medium (TCBS), and colonies with morphological resemblance to V. cholerae were isolated. The cultures were identified phenotypically using a dichotomous key based on biochemical characteristics. The total DNA extracted was amplified by PCR to detect ompW and by multiplex PCR to detect the virulence genes ctx, tcp, zot and rfbO1. The results of the phenotypic and genotypic identification were compared. Nine strains of V. cholerae were identified phenotypically, five of which were confirmed by detection of the species-specific gene ompW. The dichotomous key was efficient at differentiating environmental strains of V. cholerae. Strains of V. cholerae were found in all four estuaries, but none possessed virulence genes.

O objetivo deste estudo foi detectar a presença potencial virulência de Vibrio cholerae isolado de estuários do Nordeste do Brasil. Amostras de água e sedimento foram coletadas e inoculadas sobre meio seletivo para víbrios (TCBS) e colônias com características morfológicas de V. cholerae foram isoladas. A identificação fenotípica seguiu chave dicotômica baseada em caraterísticas bioquímicas. Foram empregadas as técnicas de amplificação da polimerase em cadeia (PCR) utilizando o gene ompW e a de multiplex PCR para detecção de genes de virulência (ctx, tcp, zot e rfbO1). Os resultados da identificação das diferentes abordagens foram comparados. Nove cepas de V. cholerae foram identificadas fenotipicamente e cinco confirmadas através da detecção do gene ompW. A chave dicotômica utilizada foi eficiente para a confirmação da espécie. Os quatro estuários analisados apresentaram estirpes de V. cholerae, e nenhuma das cepas isoladas apresentaram genes de virulência.

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Figures

Fig. 1 -
Fig. 1 -. Map of the four estuaries Pacoti, Choró, Pirangi and Jaguaribe (Ceará, Brazil) from where water and sediment were sampled between January and April 2009.
Fig. 2 -
Fig. 2 -. Electrophoretic profile of nine strains identified genotypically as Vibrio cholerae using primers for the species-specific gene OmpW (304 pb) on PCR.
Fig. 3 -
Fig. 3 -. Electrophoretic profile of strains identified as Vibrio cholerae (Vc) using primers for the virulence genes ctxAB (536 pb), tcp (805 pb), rfbO1 (638 pb) and zot (947 pb) on multiplex PCR.
See this image and copyright information in PMC

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