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.本数据集深入探究了氯消毒可能引发或增强印度古吉拉特邦城市污水处理厂（Sewage Treatment Plants，STPs）分离菌株的抗生素耐药性（Antimicrobial Resistance，AMR）的潜力。研究从市政污水预氯化阶段共分离得到19株细菌菌株，其中革兰氏阳性菌11株、革兰氏阴性菌8株。这些菌株为野生型菌株，在正式接受消毒处理前可耐受环境应激。采用Kirby-Bauer纸片扩散法对这些分离菌株进行了药敏试验（Antimicrobial Susceptibility Testing，AST），抑菌圈（Zone of Inhibition，ZOI）结果的判读遵循美国临床和实验室标准协会（Clinical and Laboratory Standards Institute，CLSI）M100-S25标准。为评估分离菌株的固有耐药谱，首先收集了基线抑菌圈数据；随后对同一批菌株开展20ppm的体外氯化处理。之后针对暴露后的菌株，选用覆盖β-内酰胺类、氨基糖苷类、四环素类、糖肽类、大环内酯类、氟喹诺酮类、抗叶酸类等重要药理学类别的31种抗生素开展药敏测试，以评估其对抗生素应答的变化。通过对比氯化前后的抑菌圈数值，本数据集发现多株分离菌株的抗生素敏感性出现显著下降。部分菌株从敏感（S）类别转变为中介（I）或耐药（R）类别，这提示可能存在应激诱导的耐药基因选择、突变或激活过程。研究人员通过柱状图、密度图、药敏图谱热图以及相关矩阵等可视化方法，探究了抗生素类别与耐药性出现之间的模式与关联。其中氨苄西林、氧氟沙星、四环素、克林霉素和氯霉素等抗生素的类别变化尤为显著，且多数情况下革兰氏阳性菌的反应更为明显。本研究结果对当前主流的污水消毒工艺提出了重要警示：即便反复或亚致死剂量的氯暴露，也可能改变细菌的耐药表型。本数据集经过精心筛选，可为探究环境抗生素耐药性动态与消毒工艺之间关联的研究者提供宝贵的研究资源，助力后续风险评估、监测工作以及污水处理工艺的优化，以减少耐药基因在环境微生物组中的意外传播。