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<p>Pharmaceutical effluents are the major contributors to antibiotic pollution, significantly increasing antibiotic resistance in the microbial communities, demanding diverse methodologies for treatment and waste disposal. The paper describes the presence of various ampicillin-resistant (100–15000&#xa0;µg/mL) bacterial strains in soil (15&#xa0;cm depth) and wastewater (one meter below the surface water) over 12&#xa0;months from the pharma discharges at Himachal Pradesh, India, belonging to phylum Firmicutes, Pseudomonadota, and Actinobacteria, with predominant genera of <i>Bacillus</i> (17%), <i>Enterobacter</i> (13%), <i>Serratia</i> (9%), and <i>Brevibacillus</i> (9%). The seasonal variation of ampicillin-tolerant strains was 34.78% during summer, 17.39% in winter, 30.44% in monsoon, and 17.39% in autumn. The diversity indices identified summer as the most favourable season for bacterial growth and proliferation, which was also supported by the Shannon (2.079) and Simpson (0.875) indices for species diversity. Among the isolated strains, 21.74% exhibited resistance to at least three different classes of antibiotics, confirming their multidrug resistance (MDR) status. Seventeen strains displayed β-lactamase production (0.4–0.24 U/mL) while 5 exhibited drug-efflux (4–12&#xa0;h) as a major mechanism of resistance, and only one strain revealed both mechanisms. Three strains, <i>Enterobacter hormaechei</i> RSM5, <i>Lysinibacillus macrolides</i> RSC5, and <i>Micrococcus aloeverae</i> RSC13, were able to tolerate ampicillin up to 15,000&#xa0;μg/mL with different ampicillin degradation capabilities. <i>Enterobacter hormaechei</i> RSM5 degraded 100&#xa0;μg/mL ampicillin completely with a rate constant of 1.35 × 10<sup>–3</sup>&#xa0;min<sup>−1</sup> and a half-life of 513.3&#xa0;min. As key pharmaceutical ingredients, antibiotics discharged in effluents interact with resident microbial communities, accelerating the emergence and spread of drug-resistant strains, thereby necessitating stringent policies and regulations for effective pharmaceutical waste management.</p> Graphical Abstract <p></p>

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Antibiotic-Resistant Bacterial Diversity in Pharmaceutical Discharge with their Multi-Drug Resistance Capabilities

  • 期刊论文

  • 发表日期：

    2025年10月7日

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  • Swati Srivastava,
  • Rajni Singh

摘要

Pharmaceutical effluents are the major contributors to antibiotic pollution, significantly increasing antibiotic resistance in the microbial communities, demanding diverse methodologies for treatment and waste disposal. The paper describes the presence of various ampicillin-resistant (100–15000 µg/mL) bacterial strains in soil (15 cm depth) and wastewater (one meter below the surface water) over 12 months from the pharma discharges at Himachal Pradesh, India, belonging to phylum Firmicutes, Pseudomonadota, and Actinobacteria, with predominant genera of Bacillus (17%), Enterobacter (13%), Serratia (9%), and Brevibacillus (9%). The seasonal variation of ampicillin-tolerant strains was 34.78% during summer, 17.39% in winter, 30.44% in monsoon, and 17.39% in autumn. The diversity indices identified summer as the most favourable season for bacterial growth and proliferation, which was also supported by the Shannon (2.079) and Simpson (0.875) indices for species diversity. Among the isolated strains, 21.74% exhibited resistance to at least three different classes of antibiotics, confirming their multidrug resistance (MDR) status. Seventeen strains displayed β-lactamase production (0.4–0.24 U/mL) while 5 exhibited drug-efflux (4–12 h) as a major mechanism of resistance, and only one strain revealed both mechanisms. Three strains, Enterobacter hormaechei RSM5, Lysinibacillus macrolides RSC5, and Micrococcus aloeverae RSC13, were able to tolerate ampicillin up to 15,000 μg/mL with different ampicillin degradation capabilities. Enterobacter hormaechei RSM5 degraded 100 μg/mL ampicillin completely with a rate constant of 1.35 × 10–3 min−1 and a half-life of 513.3 min. As key pharmaceutical ingredients, antibiotics discharged in effluents interact with resident microbial communities, accelerating the emergence and spread of drug-resistant strains, thereby necessitating stringent policies and regulations for effective pharmaceutical waste management.

Graphical Abstract