## 3 Results and Discussion
This is a very important factor for water bodies located in agricultural areas. Imipenem belongs to carbapenems, a group within \(\beta\)-lactam antibiotics. It is a derivative of the natural antibiotic thienamycin produced by the bacteria _Streptomyces cattleya_. It is applied in the treatment of bacterial bloodstream infections, complicated infections in the genitourinary tract, abdominal cavity, skin and soft tissue infections, lung infections and pneumonia (2017). \(\beta\)-lactams occur as contaminants in industrial wastewater, and they undergo only 20-30% removal in wastewater treatment processes (2017), while they are among the most widely used bacteriides (2017). In the case of this research, an important criterion for selecting these antibiotics was the fact that they are used to combat infections of parts of the human body exposed to potential contact with microorganisms that may be present in the water (skin, mucous membranes, and respiratory and digestive tracts). On the other hand, these antibiotics and the antibiotic-resistant bacteria related to them can be found in surface runoff from nearby agricultural areas and municipal wastewater from tourist facilities. Drug-resistant microorganisms are increasingly common in the environment [30; 31; 32]. Therefore, recognizing potential environmental reservoirs of antibiotic-resistant bacteria is becoming increasingly important [18]. Antibiotic-resistant bacteria present in surface waters may serve as a source of resistance genes for potentially pathogenic strains [1]. Due to the possibility of horizontal gene transfer, the spread of antibiotic resistance is possible even between different bacterial species [33]. The pressure of the pharmaceutical contaminants can intensify the process [34], although the presence of antibiotic-resistant bacteria and the genes responsible for the resistance may not correspond directly with the concentrations of antibiotics in water [35]. On the other hand, the increase in the number of antibiotic-resistant strains may correlate with water contamination with biocides [35] and heavy metals [1]. The problem is particularly important in the case of natural water bodies used for recreational purposes [18; 36; 37; 38], such as the water reservoir under study. It should be noted that the phenomenon of resistant microorganisms can also be observed in environments that are not subject to direct selective pressure caused by the presence of antibiotics and/or their metabolites [18]. The results of studies conducted in different parts of the world confirm both the possibility of antibiotic-resistant bacteria in recreational waters and the coincidence of the characteristics of these bacteria with the gastrointestinal microflora of water users. [PERSON] et al. [39] detected multi-resistant strains of _S. aureus_ at freshwater beaches in Ohio. A convergence was also noted between \(\beta\)-lactams-resistant _E. coli_ isolated from recreational waters and bacteria from the gastrointestinal tract of people using these water bodies for bathing [18]. A study conducted in the United Kingdom by [PERSON] et al. [37] found an increased incidence of antibiotic-resistant strains of _E. coli_ in the digestive tracts of surfers who regularly use coastal waters. Numerous detected _E. coli_ strains contained the _bla_CTX-M gene found in bacteria capable of producing ESBLs and with increased resistance to fluoroquinolone antibiotics, aminoglycos and tetracyclines. In addition, [PERSON] et al. [40], in a study in Eastern Norway, observed that freshwater swimming might be a risk factor associated with gastrointestinal colonization by bacterial strains belonging to the _Enterobacteriaceae_ family and being carriers of genes conditioning their production of extended-spectrum \(\beta\)-lactamases. The possibility of exposure to antibiotic resistance factors (bacteria, genes conditioning drug resistance) via recreationally used waters was also confirmed by the study of [PERSON] et al. [41] conducted on two rivers and recreational beaches located in central Italy.