Concentrations of antibiotics predicted to select for resistant bacteria: Proposed limits for environmental regulation.

By Johan Bengtsson-Palme, D. Larsson. Environment International, 2016

837 citations recorded by the source corpus.

There are concerns that selection pressure from antibiotics in the environment may accelerate the evolution and dissemination of antibiotic-resistant pathogens. Nevertheless, there is currently no regulatory system that takes such risks into account. In part, this is due to limited knowledge of environmental concentrations that might exert selection for resistant bacteria. To experimentally determine minimal selective concentrations in complex microbial ecosystems for all antibiotics would involve considerable effort. In this work, our aim was to estimate upper boundaries for selective concentrations for all common antibiotics, based on the assumption that selective concentrations a priori need to be lower than those completely inhibiting growth. Data on Minimal Inhibitory Concentrations (MICs) were obtained for 111 antibiotics from the public EUCAST database. The 1% lowest observed MICs were identified, and to compensate for limited species coverage, predicted lowest MICs adjusted for the number of tested species were extrapolated through modeling. Predicted No Effect Concentrations (PNECs) for resistance selection were then assessed using an assessment factor of 10 to account for differences between MICs and minimal selective concentrations. The resulting PNECs ranged from 8 ng/L to 64 μg/L. Furthermore, the link between taxonomic similarity between species and lowest MIC was weak. This work provides estimated upper boundaries for selective concentrations (lowest MICs) and PNECs for resistance selection for all common antibiotics. In most cases, PNECs for selection of resistance were below available PNECs for ecotoxicological effects. The generated PNECs can guide implementation of compound-specific emission limits that take into account risks for resistance promotion.

Subfields: Applied Microbiology and Biotechnology, Molecular Biology, Pollution

View Paper: https://www.semanticscholar.org/paper/03e9f80907e3fb296821a44cce26d6e30153f9e3

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Citations in the corpus

• Antimicrobials and Antibiotic-Resistant Bacteria: A Risk to the Environment and to Public Health (2020, background): “It is estimated that the MSC for a diverse range of microorganisms ranges between 1/4 and 1/230 of the MIC values [33,34].”
• Emerging contaminants: A One Health perspective (2024, neutral): “99,100 When these potentially toxic leachates seep out or over fl ow into water bodies, they can adversely affect aquatic organisms.”
• Antibiotic pollution in surface fresh waters: Occurrence and effects. (2019, background): “For example, Bengtsson-Palme 16 and Larsson (2016) reviewed the effects of antibiotics on clinically relevant bacteria and 17 found the lowest minimal inhibitory concentrations (MIC) at 2 µg/L for 13 antibiotics, 18 corresponding to the lowest concentration tested.”