Abstract
The genus Vibrio comprises pathogens ubiquitous to marine environments. This study evaluated the cultivable Vibrio community in the Guanabara Bay (GB), a recreational, yet heavily polluted estuary in Rio de Janeiro, Brazil. Over one year, 66 water samples from three locations along a pollution gradient were investigated. Isolates were identified by MALDI-TOF mass spectrometry, revealing 20 Vibrio species, including several potential pathogens. Antimicrobial susceptibility testing confirmed resistance to aminoglycosides, beta-lactams (including carbapenems and third-generation cephalosporins), fluoroquinolones, sulfonamides, and tetracyclines. Four strains were producers of extended-spectrum beta-lactamases (ESBL), all of which carried beta-lactam and heavy metal resistance genes. The toxR gene was detected in all V. parahaemolyticus strains, although none carried the tdh or trh genes. Higher bacterial isolation rates occurred in months marked by higher water temperatures, lower salinities, and lower phosphorus and nitrogen concentrations. The presence of non-susceptible Vibrio spp. was related to indicators of eutrophication and sewage inflow. DNA fingerprinting analyses revealed that V. harveyi and V. parahaemolyticus strains non-susceptible to antimicrobials might persist in these waters throughout the year. Our findings indicate the presence of antimicrobial-resistant and potentially pathogenic Vibrio spp. in a recreational environment, raising concerns about the possible risks of human exposure to these waters.
Highlights
The genus Vibrio includes Gram-negative curved rod-shaped Gammaproteobacteria autochthonous in aquatic environments, where they play important roles in nutrient cycling [1]. These bacteria comprise a remarkably diverse group and are known for their ability to rapidly adapt to environmental changes and for their intrinsic competency to acquire and transmit exogenous DNA via horizontal gene transfer (HGT)
This study provides new insights regarding the occurrence, abundance, and diversity of Vibrio spp. isolated from water samples across a pollution gradient in an urban Brazilian estuary
Our results showed that most of the extended-spectrum beta-lactamases (ESBL)-positive bacteria were isolated from this location, all of which carried beta-lactam and heavy metal resistance genes, as well as high Multiple antimicrobial resistance (MAR) indexes, suggesting an antimicrobial resistance hotspot
Summary
The genus Vibrio includes Gram-negative curved rod-shaped Gammaproteobacteria autochthonous in aquatic environments, where they play important roles in nutrient cycling [1] These bacteria comprise a remarkably diverse group and are known for their ability to rapidly adapt to environmental changes and for their intrinsic competency to acquire and transmit exogenous DNA via horizontal gene transfer (HGT). Vibrio spp. infections usually occur via the consumption of contaminated seafood or exposure to contaminated water and tend to be self-limiting. They can be fatal, especially in immunocompromised patients or upon failure of antimicrobial therapy [6,7]
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