Data to accompany paper "Rolbiecki, D.; Korzeniewska, E.; Czatzkowska, M.; Harnisz, M. The Impact of Chlorine Disinfection of Hospital Wastewater on Clonal Similarity and ESBL-Production in Selected Bacteria of the Family Enterobacteriaceae. Int. J. Environ. Res. Public Health 2022, 19, 13868. https://doi.org/10.3390/ijerph192113868" 1. Bacterial Strains Data.xlsx - characteristics of the strains obtained in this study (Strain number, medium used for isolation, research season, research site, isolation date. 2. Data of Phenotypic Detection of ESBL Producers.xlsx - ESBL+ bacterial detection analysis results: two-stage detection using chromID™ ESBL medium and Combined Disc Test (CD); inhibition zones for antibiotic discs; ESBL analysis result. 3. ERIC PCR Locus Molecular Weight.xlsx - frequency of occurrence of fragments with specific molecular weights during ERIC-PCR analysis. 4. ESBL Positive Strains Characterisation.xlsx - individual results of molecular analyzes of DNA isolated from strains (results of PCR tests, identification by sequencing). 5. SimilarityMatrixCorrelation.xlsx - matrix of similarities by calculating Pearson’s correlation coefficient. Pearson’s correlation coefficient was calculated based on the intensity of ethidium bromide fluorescence along normalized migration distances for the two fingerprints. 6. similarityMatrixDice.xlsx - matrix of similarities by calculating the Dice coefficient. The Dice coefficient approach, similarities are assessed based on the presence or absence (0/1 values) of bands of the same molecular weight in fingerprint patterns