From Survivors to Superbugs: Evaluating AMR Trajectories in Wastewater Bacteria Under Sequential Chlorination Stress

The potential for chlorine disinfection to cause or increase antimicrobial resistance (AMR) in bacterial isolates obtained from urban sewage treatment plants (STPs) in Gujarat, India, is thoroughly examined in this dataset. From the pre-chlorination stage of municipal wastewater, a total of 19 bacterial strains, 11 Gram-positive and 8 Gram-negative were isolated. These strains are wild-type organisms that can withstand environmental stress before being formally disinfected. Using the Kirby-Bauer disk diffusion technique, these isolates were subjected to antimicrobial susceptibility testing (AST). The Clinical and Laboratory Standards Institute (CLSI) M100-S25 criteria were followed in the interpretation of the zone of inhibition (ZOI) results. In order to evaluate the isolates inherent resistance profiles, baseline ZOI data were first gathered. The same isolates were then subjected to 20 ppm of in vitro chlorination. A panel of 31 antibiotics from important pharmacological classes, such as β-lactams, aminoglycosides, tetracyclines, glycopeptides, macrolides, fluoroquinolones, antifolates, and others, were then tested for post-exposure susceptibility to assess changes in antibiotic response. By comparing ZOI values before and after chlorination, the dataset finds several cases in which isolates showed a noticeable decrease in antibiotic sensitivity. Indicating potential stress induced selection, mutation, or activation of resistance genes, a number of isolates moved from the susceptible (S) to the intermediate (I) or resistant (R) categories. To find patterns and connections between antibiotic classes and the emergence of resistance, visualization methods such bar graphs, density plots, antibiogram heatmaps, and correlation matrices were used. Antibiotics such as ampicillin, ofloxacin, tetracycline, clindamycin, and chloramphenicol showed particularly noteworthy category changes, with Gram-positive isolates exhibiting a more marked reaction in many instances. The findings raise significant concerns regarding the methods used to disinfect wastewater today as they imply that even repeated or sub-lethal exposure to chlorine might alter bacterial resistance phenotypes. Researchers looking at the relationship between ambient AMR dynamics and disinfection procedures may find this well selected dataset to be a useful resource. In order to reduce the unintentional spread of resistance characteristics in environmental microbiomes, it helps upcoming risk evaluations, surveillance initiatives, and the improvement of wastewater treatment procedures.