Genes de virulencia e resistência antimicrobiana de Vibrio parahaemolyticus em áreas de ostreicultura

This study aimed to quantify Vibrio spp. and evaluate the profile of antimicrobial susceptibility and virulence factors in Vibrio parahaemolyticus strains in the samples of oysters collected from two estuaries of the Baixo Sul, Bahia. The samples were collected between June 2015 and January 2016 from natural banks (E1) (oyster) and from cultivation areas (E2) (water and oyster). For the quantification of Vibrio spp., the most probable number (MPN) was determined and the characterization of V. parahaemolyticus marker (species-specific) gene tl was performed. Pathogenicity was observed with the Kanagawa test, and the presence of the tdh, trh and ure genes were tested. The antimicrobial sensitivity test included disc diffusion method with 15 antimicrobial discs, β-lactamase enzyme production, and the presence of blaTEM, blaSHV, and blaCTX-M. The maximum density of Vibrio spp. in the samples from cultivation was 4.70 log MPN g-1 and extractivism was 6.10 log MPN g-1, with the temperature being the most influencing variable on the presence of microorganisms in the cultivation area (E2). The tl gene was detected in 71% of the isolates, without the presence of tdh, trh and ure genes. All strains of V. parahaemolyticus were Kanagawa negative. High antimicrobial resistance was observed in the β-lactam antibiotics (cephalothin - 72%, ampicillin - 60%) and aminoglycosides (amikacin - 64%), with multi-resistance in 88% of the strains of V. parahaemolyticus, of which 68% of the resistance was mediated by plasmids. Phenotypically, no production of β-lactamase enzymes was observed, but the presence of blaTEM genes was observed. The multiresistant character of plasmids reported in V. parahaemolyticus strains increases the concern about native bacteria in the marine environment since it can potentially compromise the control of this bacterium infection in bivalve mollusks.