Résumé
Little information is available on the presence of V. cholerae (VC), V. parahaemolyticus (VP) and V. vulnificus (VV) in the Amazonian region where the last cholera epidemic occurred in the early 1990s. The main objective of this study was to investigate occurrence of these vibrios in the Guajará Bay, an important estuary along the Amazonian coast where Belém, the largest city of the Amazonia is located. Water and zooplankton samples were collected in September, 2017, at five stations in the estuary along a salinity gradient, from 0 to 20‰. Temperature of the water was ca. 29°C. Enumeration of the three vibrio species was accomplished using APW enrichment and MPN-real-time PCR analysis. APW broths were spread onto CHROMagar™ Vibrio and presumptive Vibrio colonies were isolated for molecular identification. The total number of VC and VP varied from ca. 10 MPN/L to 110 MPN/L, and of VV from 4 MPN/L to 46 MPN/L. Highest levels were recorded for VC and VV when the salinity was ca. 2-4.6 ‰, and ca. 4.6 ‰, respectively. No pattern was observed for VP that could be correlated with salinity. The number of potentially pathogenic VP tdh+ and VP trh2+ varied from ca. 1 MPN/L to 4 MPN/L, and from 1 MPN/L to 2 MPN/L, respectively. The three vibrios were detected on the copepods (Acartia tonsa) and on Cirriped nauplii, depending on the sites and the salinity. Of 109 Vibrio strains isolated at the five stations included in this study, 67 were identified as V. cholerae, 27 V. parahaemolyticus, and 15 V. vulnificus. The vibrio species were widespread through the large salinity gradient of the Guajará bay, showing its relevance as a potential reservoir of these bacteria.