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Open AccessJournal ArticleDOI

Selection of resistant bacteria at very low antibiotic concentrations.

TLDR
It is suggested that the low antibiotic concentrations found in many natural environments are important for enrichment and maintenance of resistance in bacterial populations.
Abstract
The widespread use of antibiotics is selecting for a variety of resistance mechanisms that seriously challenge our ability to treat bacterial infections. Resistant bacteria can be selected at the high concentrations of antibiotics used therapeutically, but what role the much lower antibiotic concentrations present in many environments plays in selection remains largely unclear. Here we show using highly sensitive competition experiments that selection of resistant bacteria occurs at extremely low antibiotic concentrations. Thus, for three clinically important antibiotics, drug concentrations up to several hundred-fold below the minimal inhibitory concentration of susceptible bacteria could enrich for resistant bacteria, even when present at a very low initial fraction. We also show that de novo mutants can be selected at sub-MIC concentrations of antibiotics, and we provide a mathematical model predicting how rapidly such mutants would take over in a susceptible population. These results add another dimension to the evolution of resistance and suggest that the low antibiotic concentrations found in many natural environments are important for enrichment and maintenance of resistance in bacterial populations.

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Journal ArticleDOI

Widespread occurrence and potential for biodegradation of bioactive contaminants in Congaree National Park, USA

TL;DR: Endogenous sterols and hormones, which may originate from humans or wildlife, were detected in water and sediment samples throughout Congaree National Park, but synthetic hormones were detected only once, suggesting a comparatively low risk of adverse impacts.
Journal ArticleDOI

Evolution of Resistance to Continuously Increasing Streptomycin Concentrations in Populations of Escherichia coli

TL;DR: A novel chemostat method was used to observe the evolution of resistance to streptomycin in a sensitive population of Escherichia coli, which grew while the concentration of antibiotic was constantly increasing, creating a “lull period” in which there were few bacterial cells growing in the chemostats.
Journal ArticleDOI

Not All Antibiotic Use Practices in Food-Animal Agriculture Afford the Same Risk

TL;DR: When considering the risks of different antibiotic use practices in agriculture, it would be prudent to focus attention on practices that involve high doses, oral delivery, and residues of antibiotics that remain active in soils.
Book ChapterDOI

Veterinary Drug Residues in Foods

TL;DR: In this paper, the broader issues associated with residues of veterinary drugs in food products of animal origin are dealt with, such as risk assessment, risk management, major causes of residues and major classes of drug residues.
Journal ArticleDOI

Large-scale biogeographical patterns of antibiotic resistome in the forest soils across China.

TL;DR: A national-scale investigation of soil resistomes in pristine forests across China found numerous detected ARGs conferring resistance to major classes of modern antibiotics were identified and indicated forest soils as a potential source of resistance traits.
References
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Journal ArticleDOI

Stochastic Gene Expression in a Single Cell

TL;DR: This work constructed strains of Escherichia coli that enable detection of noise and discrimination between the two mechanisms by which it is generated and reveals how low intracellular copy numbers of molecules can fundamentally limit the precision of gene regulation.
Journal ArticleDOI

Antibiotics in the aquatic environment - A review - Part II

TL;DR: This review brings up important questions that are still open, and addresses some significant issues which must be tackled in the future for a better understanding of the behavior of antibiotics in the environment, as well as the risks associated with their occurrence.
Journal ArticleDOI

Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment

TL;DR: Global efforts are needed to promote more judicious use of prophylactic antibiotics in aquaculture as accumulating evidence indicates that unrestricted use is detrimental to fish, terrestrial animals, and human health and the environment.
Journal ArticleDOI

Antibiotic resistance and its cost: is it possible to reverse resistance?

TL;DR: The findings suggest that the fitness costs of resistance will allow susceptible bacteria to outcompete resistant bacteria if the selective pressure from antibiotics is reduced, and that the rate of reversibility will be slow at the community level.
Journal ArticleDOI

Antibiotics and antibiotic resistance genes in natural environments.

TL;DR: The large majority of antibiotics currently used for treating infections and the antibiotic resistance genes acquired by human pathogens each have an environmental origin and the function of these elements in their environmental reservoirs may be very distinct from the “weapon-shield” role they play in clinical settings.
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