Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>

ABSTRACT High-level resistance often evolves when populations of bacteria are exposed to antibiotics, by either mutations or horizontally acquired genes. There is also variation in the intrinsic resistance levels of different bacterial strains and species that is not associated with any known histor...

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Autores principales:	Otmane Lamrabet, Mikaël Martin, Richard E. Lenski, Dominique Schneider
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	Escherichia coli antibiotic resistance evolution mutation accumulation pleiotropy Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/fa8434345a574e8f8cf7ab7eb704f845
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spelling	oai:doaj.org-article:fa8434345a574e8f8cf7ab7eb704f8452021-11-15T15:55:24ZChanges in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>10.1128/mBio.00189-192150-7511https://doaj.org/article/fa8434345a574e8f8cf7ab7eb704f8452019-04-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00189-19https://doaj.org/toc/2150-7511ABSTRACT High-level resistance often evolves when populations of bacteria are exposed to antibiotics, by either mutations or horizontally acquired genes. There is also variation in the intrinsic resistance levels of different bacterial strains and species that is not associated with any known history of exposure. In many cases, evolved resistance is costly to the bacteria, such that resistant types have lower fitness than their progenitors in the absence of antibiotics. Some longer-term studies have shown that bacteria often evolve compensatory changes that overcome these tradeoffs, but even those studies have typically lasted only a few hundred generations. In this study, we examine changes in the susceptibilities of 12 populations of Escherichia coli to 15 antibiotics after 2,000 and 50,000 generations without exposure to any antibiotic. On average, the evolved bacteria were more susceptible to most antibiotics than was their ancestor. The bacteria at 50,000 generations tended to be even more susceptible than after 2,000 generations, although most of the change occurred during the first 2,000 generations. Despite the general trend toward increased susceptibility, we saw diverse outcomes with different antibiotics. For streptomycin, which was the only drug to which the ancestral strain was highly resistant, none of the evolved lines showed any increased susceptibility. The independently evolved lineages often exhibited correlated responses to the antibiotics, with correlations usually corresponding to their modes of action. On balance, our study shows that bacteria with low levels of intrinsic resistance often evolve to become even more susceptible to antibiotics in the absence of corresponding selection. IMPORTANCE Resistance to antibiotics often evolves when bacteria encounter antibiotics. However, bacterial strains and species without any known exposure to these drugs also vary in their intrinsic susceptibility. In many cases, evolved resistance has been shown to be costly to the bacteria, such that resistant types have reduced competitiveness relative to their sensitive progenitors in the absence of antibiotics. In this study, we examined changes in the susceptibilities of 12 populations of Escherichia coli to 15 antibiotics after 2,000 and 50,000 generations without exposure to any drug. The evolved bacteria tended to become more susceptible to most antibiotics, with most of the change occurring during the first 2,000 generations, when the bacteria were undergoing rapid adaptation to their experimental conditions. On balance, our findings indicate that bacteria with low levels of intrinsic resistance can, in the absence of relevant selection, become even more susceptible to antibiotics.Otmane LamrabetMikaël MartinRichard E. LenskiDominique SchneiderAmerican Society for MicrobiologyarticleEscherichia coliantibiotic resistanceevolutionmutation accumulationpleiotropyMicrobiologyQR1-502ENmBio, Vol 10, Iss 2 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	Escherichia coli antibiotic resistance evolution mutation accumulation pleiotropy Microbiology QR1-502
spellingShingle	Escherichia coli antibiotic resistance evolution mutation accumulation pleiotropy Microbiology QR1-502 Otmane Lamrabet Mikaël Martin Richard E. Lenski Dominique Schneider Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
description	ABSTRACT High-level resistance often evolves when populations of bacteria are exposed to antibiotics, by either mutations or horizontally acquired genes. There is also variation in the intrinsic resistance levels of different bacterial strains and species that is not associated with any known history of exposure. In many cases, evolved resistance is costly to the bacteria, such that resistant types have lower fitness than their progenitors in the absence of antibiotics. Some longer-term studies have shown that bacteria often evolve compensatory changes that overcome these tradeoffs, but even those studies have typically lasted only a few hundred generations. In this study, we examine changes in the susceptibilities of 12 populations of Escherichia coli to 15 antibiotics after 2,000 and 50,000 generations without exposure to any antibiotic. On average, the evolved bacteria were more susceptible to most antibiotics than was their ancestor. The bacteria at 50,000 generations tended to be even more susceptible than after 2,000 generations, although most of the change occurred during the first 2,000 generations. Despite the general trend toward increased susceptibility, we saw diverse outcomes with different antibiotics. For streptomycin, which was the only drug to which the ancestral strain was highly resistant, none of the evolved lines showed any increased susceptibility. The independently evolved lineages often exhibited correlated responses to the antibiotics, with correlations usually corresponding to their modes of action. On balance, our study shows that bacteria with low levels of intrinsic resistance often evolve to become even more susceptible to antibiotics in the absence of corresponding selection. IMPORTANCE Resistance to antibiotics often evolves when bacteria encounter antibiotics. However, bacterial strains and species without any known exposure to these drugs also vary in their intrinsic susceptibility. In many cases, evolved resistance has been shown to be costly to the bacteria, such that resistant types have reduced competitiveness relative to their sensitive progenitors in the absence of antibiotics. In this study, we examined changes in the susceptibilities of 12 populations of Escherichia coli to 15 antibiotics after 2,000 and 50,000 generations without exposure to any drug. The evolved bacteria tended to become more susceptible to most antibiotics, with most of the change occurring during the first 2,000 generations, when the bacteria were undergoing rapid adaptation to their experimental conditions. On balance, our findings indicate that bacteria with low levels of intrinsic resistance can, in the absence of relevant selection, become even more susceptible to antibiotics.
format	article
author	Otmane Lamrabet Mikaël Martin Richard E. Lenski Dominique Schneider
author_facet	Otmane Lamrabet Mikaël Martin Richard E. Lenski Dominique Schneider
author_sort	Otmane Lamrabet
title	Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
title_short	Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
title_full	Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
title_fullStr	Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
title_full_unstemmed	Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>
title_sort	changes in intrinsic antibiotic susceptibility during a long-term evolution experiment with <named-content content-type="genus-species">escherichia coli</named-content>
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/fa8434345a574e8f8cf7ab7eb704f845
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Changes in Intrinsic Antibiotic Susceptibility during a Long-Term Evolution Experiment with <named-content content-type="genus-species">Escherichia coli</named-content>

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