Pheno-genotypic resistance in bacteria from freshwater

Resumen

Brazil is a privileged country in terms of its natural resources, and among these, water resources play a significant ecological, economic, strategic, and social role. Despite this high potential, anthropogenic action such as the discharge of untreated effluents into rivers, lakes, and streams have negatively influenced water quality, causing a serious imbalance in the aquatic ecosystem. It is important to note that in Brazil, there are no public policies related to improper disposal of waste in the aquatic environment, and this factor contributes to its pollution. Among the common pollutants, it is possible to highlight antimicrobial drugs, as several studies have pointed out the problem of increasing microbial resistance worldwide, including in various environments, including aquatic ones. Based on this and considering that the bacterial microbiota found in live fish is directly related to the microbiota of the environment, this study aimed to evaluate the diversity and antimicrobial resistance profile of bacteria isolated from fish from the Guandu River, Seropédica-RJ. Fish from the Guandu River were collected and identified. Subsequently, necropsy was performed on these fish, and swab samples were collected from their intestines. Bacterial isolation, biochemical and proteomic identification of isolates, phenotypic detection of antimicrobial resistance, as well as extraction of bacterial DNA and amplification of resistance genes, were performed using these samples. A total of 30 fish were collected and identified, with Pimelodus maculatus, Geophagus brasiliensis, and Oligoplites saliens being the most common species. From the intestinal material of these fish, 32 bacterial strains were isolated, distributed among 11 species. Escherichia coli was the bacterial species with the highest incidence. The bacteria showed resistance to gentamicin, sulfazothrim, ampicillin, cefotaxime, ceftazidime, and amoxicillin with clavulanate. After analysis, none of them showed a phenotypic profile for β-lactamase production, but the genes bla_SHV, bla_CTX-M, qnrS, and mcr-1 were detected in the bacteria. These results highlight the urgent need to create public policies for constant monitoring of aquatic environments, as there are bacteria resistant to a large number of antimicrobials tested in fish from the Guandu River, as well as the presence of resistance genes, indicating the possibility of resistance dissemination throughout the ecosystem. Thus, the present study demonstrates extreme relevance in the field of One Health, alerting to the importance of observing all environments in an interconnected way.