Antibiotic resistance shaping multi-level population biology of bacteria

Baquero, Fernando; Tedim, Ana P.; Coque, Teresa M.

doi:10.3389/fmicb.2013.00015

Cited by 160 publications

(136 citation statements)

References 250 publications

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“…Moreover, we observed that the proportion of gene cassette variants in the hospital effluent was very low but increased along the wastewater flow. Antibiotics might indeed enrich the more efficient adaptive genes (Blázquez et al, 2012;Baquero et al, 2013).…”

Section: Gene Cassette Diversity and Shufflingmentioning

confidence: 99%

Quantitative and qualitative impact of hospital effluent on dissemination of the integron pool

et al. 2013

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There is increasing evidence that human activity, and especially the resulting effluent, has a major role in the dissemination of bacterial antibiotic-resistance determinants in the environment. Hospitals are the major antibiotic consumers and thus facilitate the spread of antibiotic resistance. Questions are increasingly being raised about the management of hospital effluents, but their involvement in antibiotic-resistance dissemination has never been assessed. Integrons are a paradigm of genetic transfer between the environmental resistome and both commensal and pathogenic bacteria. In order to assess the impact of hospital activities on antibiotic-resistance dissemination in the environment, we monitored integrons and their gene cassettes in hospital effluents, and their release in the environment. We found that bacterial communities present in a hospital effluent contained a high proportion of integrons. In terms of both their gene cassette diversity and gene cassette arrays, the urban effluent and municipal wastewater treatment plant (WWTP) influent were most similar, whereas the hospital effluent and recirculation sludge exhibited very specific patterns. We found that anthropogenic activities led to the release of abundant integrons and antibiotic-resistance gene cassettes, but we observed no specific impact of hospital activities on the receiving environment. Furthermore, although the WWTP did not reduce the normalized integron copy number, it reduced the diversity of gene cassette arrays contained in the raw wastewater, underlining the effect of the biological treatment on the anthropogenic integron pool arriving at the WWTP.

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Section: Gene Cassette Diversity and Shufflingmentioning

confidence: 99%

Quantitative and qualitative impact of hospital effluent on dissemination of the integron pool

et al. 2013

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“…Consequently, if frequencies of antibiotic resistance are reduced following, for example, reduced selective pressures, then MGEs harboring resistance determinants can continuously move on to other recipients of the same or different species and promote their persistence (Bergstrom et al, 2000;Baquero et al, 2013). To gain more knowledge on the basic processes controlling the frequencies of antibiotic resistance in bacterial populations, it is essential that we better understand the population dynamics and evolution of bacteria with acquired MGEs encoding antibiotic resistance in both the presence and absence of antibiotic selective pressures (Johnsen et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

The evolutionary dynamics of integrons in changing environments

2016

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Integrons are genetic elements that are common in bacteria and are hotspots for genome evolution. They facilitate the acquisition and reassembly of gene cassettes encoding a variety of functions, including drug resistance. Despite their importance in clinical settings, the selective forces responsible for the evolution and maintenance of integrons are poorly understood. We present a mathematical model of integron evolution within bacterial populations subject to fluctuating antibiotic exposures. Bacteria carrying a functional integrase that mediates reshuffling of cassette genes and thereby modulates gene expression patterns compete with bacteria without a functional integrase. Our results indicate that for a wide range of parameters, the functional integrase can be stably maintained in the population despite substantial fitness costs. This selective advantage arises because gene-cassette shuffling generates genetic diversity, thus enabling the population to respond rapidly to changing selective pressures. We also show that horizontal gene transfer promotes stable maintenance of the integrase and can also lead to de novo assembly of integrons. Our model generates testable predictions for integron evolution, including loss of functional integrases in stable environments and selection for intermediate gene-shuffling rates in changing environments. Our results highlight the need for experimental studies of integron population biology.

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“…β-lactamase typing has been established as an important addendum to the characterization and identification of clinical antibiotic resistance pathogens and is routinely used in many laboratories [8].…”

Section: Introductionmentioning

confidence: 99%