Anais do Congresso Paranaense de Microbiologia
IV Congress of Microbiology in Paraná

The selection of resistant bacterial strains is of great importance, as it is one of the main public health problems today. Thus, it is necessary to understand new approaches that expose the problem of selection of genes that confer resistance to antibiotics. It is known that microbial resistance is not restricted to the irrational use of antibiotics and the presence of these substances in the environment. It is believed that the presence of biocides and heavy metals in water and soil are responsible for co-selection events, which make microrganisms multiresistant. Therefore, it was found that gene expression for antimicrobial resistance and heavy metal resistance are affected by the same factors. Thus, the aim of this work was to evaluate the presence of antimicrobial resistant microorganisms in contaminated rivers, and verify the presence of possible heavy metal-mediated co-selection events. Water samples were collected from the João de Maria waterhole in Ponta Grossa (where domestic waste is dumped daily). The isolated microorganisms were inoculated on Luria-Bertani Agar plates 1 µg/ml tetracycline, 10 µg/ml tetracycline, 0.05 µg/ml ciprofloxacin and 0.5 µg/ml ciprofloxacin. The bacterial strains that were able to tolerate the presence of the antibiotics tetracycline and cirpofloxacin were tested for tolerance in nickel and cadmium, at concentrations of 4.5 µg/mL and 6 µg/mL. In solutions containing tetracycline, it was possible to isolate 35 bacterial colonies at each concentration used. In the solutions containing ciprofloxacin, 33 colonies were obtained at a concentration of 0.05 µg/mL, and 22 colonies at a concentration of 0.5 µg/mL. Among the strains characterized by antibiotic tolerance, 32 were able to tolerate the presence of nickel, and only three were tolerant to cadmium. Bacteria that showed tolerance to antibiotics and heavy metal will be tested for the possibility of co-selection. Firstly, the presence of plasmids in these strains is being verified, and later plasmid cure, checking if the genes are present in mobile elements. Additionally, co-selection can be evidenced as the selection of efflux pumps, which can confer resistance to several xenobiotics. The sample used in this work was taken from a point where riverside populations live, and it can be highlighted that environmental contamination directly interferes with antibiotic resistance genes, highlighting a public health problem not directly related to the indiscriminate use of antibiotics.