The aim of the scientific research is to search for clinically significant Escherichia coli strains carrying extended-spectrum beta-lactamases (ESBL) in the aquatic environment to understand their frequency and biodiversity. The project will focus on metagenomic analyses, including: (1) determining resistance determinants; (2) phenotypic and genotypic typing of isolates; (3) whole-genome sequencing of selected isolates to map genetic elements involved in ESBL acquisition. Bacteria will be isolated from the Łeba River and five wastewater treatment plants serving less than 100,000 p.e. E. coli isolation will be done on chromogenic media with an antibiotic determining ESBL multidrug resistance. Selected isolates will undergo molecular analysis through DNA sequencing, and sequences will be analyzed using available databases. Data will be compared with clinical data to assess genetic diversity resulting from environmental pressure. The project will help determine the role of the aquatic environment in spreading multidrug-resistant bacteria and understand genetic differentiation mechanisms between environmental and clinical isolates. These actions align with the objectives of the new EU Water Framework Directive, which requires better monitoring of pathogens and antibiotic resistance. The project will also develop the Applicant's skills in molecular biology, enabling Gdańsk University of Technology to gain expertise in molecular analysis of antibiotic resistance in the environment.