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<p>Urban rivers are increasingly facing contamination and degradation due to unregulated human activities and are becoming significant reservoirs for pollutants, including toxic heavy metals (HMs) and antibiotics. This co-occurrence of antibiotics and HMs in water bodies may pose greater health and environmental concerns as HMs can co-select for antibiotic-resistant bacteria, leading to a higher prevalence of antibiotic resistance (ABR) genes/bacteria. This study investigates the co-selection of HMs and ABR in Enterobacteriaceae strains isolated from the polluted urban stretch of the Mula-Mutha River flowing through Pune Metropolitan (India). Water samples were collected from five different sites of the river, and physicochemical parameters and metal concentrations were assessed, along with microbiological profiling. Elevated levels of toxic HMs, including arsenic (As,&#xa0;1010&#xa0;µg/L), lead (Pb, 90&#xa0;µg/L), cadmium (Cd, 42&#xa0;µg/L), and chromium (Cr, 163&#xa0;µg/L) were recorded at one of the urban sites (Mhatre Bridge), surpassing the World Health Organization (WHO) thresholds, marking it as a contamination hotspot. Eighty-eight Enterobacteriaceae isolates were obtained, of which 41 (46.5%) were multidrug-resistant (MDR), while one was extensively drug-resistant (XDR). Out of these, 33 isolates were used for further investigation. ABR levels were highest against cephalosporins (93.9%) and β-lactam/β-lactamase inhibitor combinations (67.7%). Thirteen isolates (39.3%) exhibited multiple antibiotic resistance (MAR) indices ≥ 0.2, suggesting exposure to high-risk environments. Heavy metal resistance (HMR) profiling revealed minimum inhibitory concentrations (MICs) exceeding 1500&#xa0;mg/L for Mn, Cr, As, and Pb in multiple isolates, while the multiple HM resistance (MHMR) index reached a value of up to 1.0 at two urban sampling sites. Pearson correlation analysis revealed strong associations between HMR and ABR, including arsenic–lomefloxacin (<i>r</i> = 0.43), copper–cefotaxime (<i>r</i> = 0.46), and lead–piperacillin tazobactam (<i>r</i> = 0.365), suggesting co-selection via shared resistance mechanisms. These findings hold significance and highlight the convergence of chemical and biological pollution in shaping resistant microbial communities and emphasize the urgent need for integrated river basin monitoring and pollution control strategies.</p>

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Co-selection of heavy metal and antibiotic resistance in Enterobacteriaceae members from Mula-Mutha River (Pune, India)

  • 期刊论文

  • 发表日期：

    2026年3月24日

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  • Pramod Barathe,
  • Sagar Reddy,
  • Varsha Shriram,
  • Vinay Kumar

摘要

Urban rivers are increasingly facing contamination and degradation due to unregulated human activities and are becoming significant reservoirs for pollutants, including toxic heavy metals (HMs) and antibiotics. This co-occurrence of antibiotics and HMs in water bodies may pose greater health and environmental concerns as HMs can co-select for antibiotic-resistant bacteria, leading to a higher prevalence of antibiotic resistance (ABR) genes/bacteria. This study investigates the co-selection of HMs and ABR in Enterobacteriaceae strains isolated from the polluted urban stretch of the Mula-Mutha River flowing through Pune Metropolitan (India). Water samples were collected from five different sites of the river, and physicochemical parameters and metal concentrations were assessed, along with microbiological profiling. Elevated levels of toxic HMs, including arsenic (As, 1010 µg/L), lead (Pb, 90 µg/L), cadmium (Cd, 42 µg/L), and chromium (Cr, 163 µg/L) were recorded at one of the urban sites (Mhatre Bridge), surpassing the World Health Organization (WHO) thresholds, marking it as a contamination hotspot. Eighty-eight Enterobacteriaceae isolates were obtained, of which 41 (46.5%) were multidrug-resistant (MDR), while one was extensively drug-resistant (XDR). Out of these, 33 isolates were used for further investigation. ABR levels were highest against cephalosporins (93.9%) and β-lactam/β-lactamase inhibitor combinations (67.7%). Thirteen isolates (39.3%) exhibited multiple antibiotic resistance (MAR) indices ≥ 0.2, suggesting exposure to high-risk environments. Heavy metal resistance (HMR) profiling revealed minimum inhibitory concentrations (MICs) exceeding 1500 mg/L for Mn, Cr, As, and Pb in multiple isolates, while the multiple HM resistance (MHMR) index reached a value of up to 1.0 at two urban sampling sites. Pearson correlation analysis revealed strong associations between HMR and ABR, including arsenic–lomefloxacin (r = 0.43), copper–cefotaxime (r = 0.46), and lead–piperacillin tazobactam (r = 0.365), suggesting co-selection via shared resistance mechanisms. These findings hold significance and highlight the convergence of chemical and biological pollution in shaping resistant microbial communities and emphasize the urgent need for integrated river basin monitoring and pollution control strategies.