scholarly journals Predation and selection for antibiotic resistance in natural environments

2016 ◽  
Vol 9 (3) ◽  
pp. 427-434 ◽  
Author(s):  
Jørgen J. Leisner ◽  
Niels O. G. Jørgensen ◽  
Mathias Middelboe
Keyword(s):  
Antibiotic Resistance ◽  
Natural Environments ◽  
Selection For

scholarly journals Selection for antibiotic resistance is reduced when embedded in a natural microbial community

2019 ◽  
Author(s):  
Uli Klümper ◽  
Mario Recker ◽  
Lihong Zhang ◽  
Xiaole Yin ◽  
Tong Zhang ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Microbial Community ◽  
Single Species ◽  
Natural Environments ◽  
Order Of Magnitude ◽  
Natural Microbial Community ◽  
Cost Of Resistance ◽  
Selection For ◽  
The Cost ◽  
Selection Of

AbstractAntibiotic resistance has emerged as one of the most pressing, global threats to public health. In single-species experiments selection for antibiotic resistance occurs at very low antibiotic concentrations. However, it is unclear how far these findings can be extrapolated to natural environments, where species are embedded within complex communities. We competed isogenic strains of Escherichia coli, differing exclusively in a single chromosomal resistance determinant, in the presence and absence of a pig fecal microbial community across a gradient of antibiotic concentration for two relevant antibiotics: gentamicin and kanamycin. We show that the minimal selective concentration was increased by more than one order of magnitude for both antibiotics when embedded in the community. We identified two general mechanisms were responsible for the increase in minimal selective concentration: an increase in the cost of resistance and a protective effect of the community for the susceptible phenotype. These findings have implications for our understanding of the evolution and selection of antibiotic resistance, and can inform future risk assessment efforts on antibiotic concentrations.

Call of the wild: antibiotic resistance genes in natural environments

2010 ◽  
Vol 8 (4) ◽  
pp. 251-259 ◽  
Author(s):  
Heather K. Allen ◽  
Justin Donato ◽  
Helena Huimi Wang ◽  
Karen A. Cloud-Hansen ◽  
Julian Davies ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Natural Environments

scholarly journals The resistome of common human pathogens

2017 ◽  
Author(s):  
Christian Munck ◽  
Mostafa M. Hashim Ellabaan ◽  
Michael Schantz Klausen ◽  
Morten O.A. Sommer
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Bacterial Pathogens ◽  
Antibiotic Resistance Genes ◽  
Gene Clusters ◽  
Species Level ◽  
Natural Environments ◽  
Human Pathogens ◽  
Bacterial Genomes ◽  
Risk Ranking

AbstractGenes capable of conferring resistance to clinically used antibiotics have been found in many different natural environments. However, a concise overview of the resistance genes found in common human bacterial pathogens is lacking, which complicates risk ranking of environmental reservoirs. Here, we present an analysis of potential antibiotic resistance genes in the 17 most common bacterial pathogens isolated from humans. We analyzed more than 20,000 bacterial genomes and defined a clinical resistome as the set of resistance genes found across these genomes. Using this database, we uncovered the co-occurrence frequencies of the resistance gene clusters within each species enabling identification of co-dissemination and co-selection patterns. The resistance genes identified in this study represent the subset of the environmental resistome that is clinically relevant and the dataset and approach provides a baseline for further investigations into the abundance of clinically relevant resistance genes across different environments. To facilitate an easy overview the data is presented at the species level at www.resistome.biosustain.dtu.dk.

scholarly journals Agrichemicals boost the effects of antibiotics on antibiotic resistance evolution

2018 ◽  
Author(s):  
Brigitta Kurenbach ◽  
Amy M Hill ◽  
William Godsoe ◽  
Sophie van Hamelsveld ◽  
Jack A Heinemann
Keyword(s):  
Antibiotic Resistance ◽  
Acquired Resistance ◽  
Genotypic Diversity ◽  
Microbial Populations ◽  
Phenotypic Variance ◽  
Short Term ◽  
Resistance Evolution ◽  
Term Evolution ◽  
Comprehensive Test ◽  
Selection For

Antibiotic resistance is medicine’s climate change: caused by human activity, and resulting in more extreme outcomes. Resistance emerges in microbial populations when antibiotics act on phenotypic variance within the population. This can arise from either genotypic diversity (resulting from a mutation or horizontal gene transfer), or from ‘adaptive’ differences in gene expression due to environmental variation. Adaptive changes can increase fitness allowing bacteria to survive at higher concentrations of the antibiotic. They can also decrease fitness, potentially leading to selection for antibiotic resistance at lower concentrations. There are opportunities for other environmental stressors to promote antibiotic resistance in ways that are hard to predict using conventional assays. Exploiting our observation that commonly used herbicides can increase or decrease the minimum inhibitory concentration (MIC) of different antibiotics, we provide the first comprehensive test of the hypothesis that the rate of antibiotic resistance evolution under specified conditions can increase, regardless of whether a herbicide increases or decreases the antibiotic MIC. Short term evolution experiments were used for various herbicide and antibiotic combinations. We found conditions where acquired resistance arises more frequently regardless of whether the exogenous non-antibiotic agent increased or decreased antibiotic effectiveness. This “damned if you do/damned if you don’t” outcome suggests that the emergence of antibiotic resistance is exacerbated by additional environmental factors that influence competition between bacteria. Our work demonstrates that bacteria may acquire antibiotic resistance in the environment at rates substantially faster than predicted from laboratory conditions.

scholarly journals Negative frequency-dependent selection maintains coexisting genotypes during fluctuating selection

2019 ◽  
Author(s):  
Caroline B. Turner ◽  
Sean W. Buskirk ◽  
Katrina B. Harris ◽  
Vaughn S. Cooper
Keyword(s):  
Evolutionary Dynamics ◽  
Burkholderia Cenocepacia ◽  
Natural Environments ◽  
Fluctuating Selection ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Fluctuating Environment ◽  
Fluctuating Environments ◽  
Negative Frequency Dependent Selection ◽  
Selection For

AbstractNatural environments are rarely static; rather selection can fluctuate on time scales ranging from hours to centuries. However, it is unclear how adaptation to fluctuating environments differs from adaptation to constant environments at the genetic level. For bacteria, one key axis of environmental variation is selection for planktonic or biofilm modes of growth. We conducted an evolution experiment with Burkholderia cenocepacia, comparing the evolutionary dynamics of populations evolving under constant selection for either biofilm formation or planktonic growth with populations in which selection fluctuated between the two environments on a weekly basis. Populations evolved in the fluctuating environment shared many of the same genetic targets of selection as those evolved in constant biofilm selection, but were genetically distinct from the constant planktonic populations. In the fluctuating environment, mutations in the biofilm-regulating genes wspA and rpfR rose to high frequency in all replicate populations. A mutation in wspA first rose rapidly and nearly fixed during the initial biofilm phase but was subsequently displaced by a collection of rpfR mutants upon the shift to the planktonic phase. The wspA and rpfR genotypes coexisted via negative frequency-dependent selection around an equilibrium frequency that shifted between the environments. The maintenance of coexisting genotypes in the fluctuating environment was unexpected. Under temporally fluctuating environments coexistence of two genotypes is only predicted under a narrow range of conditions, but the frequency-dependent interactions we observed provide a mechanism that can increase the likelihood of coexistence in fluctuating environments.

scholarly journals The Evolution of Class 1 Integrons and the Rise of Antibiotic Resistance

2008 ◽  
Vol 190 (14) ◽  
pp. 5095-5100 ◽  
Author(s):  
Michael Gillings ◽  
Yan Boucher ◽  
Maurizio Labbate ◽  
Andrew Holmes ◽  
Samyuktha Krishnan ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Lateral Transfer ◽  
Natural Environments ◽  
Class 1 Integrons ◽  
Wide Range ◽  
Human Food Chain ◽  
Class 1 ◽  
Phylogenetic Signature

ABSTRACT Class 1 integrons are central players in the worldwide problem of antibiotic resistance, because they can capture and express diverse resistance genes. In addition, they are often embedded in promiscuous plasmids and transposons, facilitating their lateral transfer into a wide range of pathogens. Understanding the origin of these elements is important for the practical control of antibiotic resistance and for exploring how lateral gene transfer can seriously impact on, and be impacted by, human activities. We now show that class 1 integrons can be found on the chromosomes of nonpathogenic soil and freshwater Betaproteobacteria. Here they exhibit structural and sequence diversity, an absence of antibiotic resistance genes, and a phylogenetic signature of lateral transfer. Some examples are almost identical to the core of the class 1 integrons now found in pathogens, leading us to conclude that environmental Betaproteobacteria were the original source of these genetic elements. Because these elements appear to be readily mobilized, their lateral transfer into human commensals and pathogens was inevitable, especially given that Betaproteobacteria carrying class 1 integrons are common in natural environments that intersect with the human food chain. The strong selection pressure imposed by the human use of antimicrobial compounds then ensured their fixation and global spread into new species.

Decline in Natural Fisheries — A Genetic Analysis and Suggestion for Recovery

1986 ◽  
Vol 43 (6) ◽  
pp. 1298-1306 ◽  
Author(s):  
Giora W. Wohlfarth
Keyword(s):  
Negative Selection ◽  
Natural Waters ◽  
Environmental Changes ◽  
Monitoring Program ◽  
Fish Populations ◽  
Natural Environments ◽  
Direct Effects ◽  
Resident Population ◽  
Selection For ◽  
Bodies Of Water

Overfishing and pollution of the aquatic environment, in addition to their direct effects on natural fisheries, may have also influenced natural fish populations genetically. Overfishing drastically reduces population size and, since the larger individuals are selectively removed, is equivalent to selection for smaller sized fish. Adaptation of natural fish populations to their environment must have been reduced by rapid environmental changes resulting from pollution and infestation. Inbreeding, negative selection, and lack of adaption are here considered as the genetic causes for the decline of natural fisheries and lack of recovery. Restocking programs involving hatchery stocks are unlikely to solve this problem, since these stocks were selected for adaptation to hatchery environments and not to natural environments. A series of studies have demonstrated heterosis of interstrain crossbreds, mainly between hatchery and wild stocks of salmonids, for performance in natural waters. Two strategies could be implemented in restocking programs: stocking spawners of a domestic strain (preferably of one sex) for interbreeding with the resident population or direct stocking of crossbred fry. This should be tested in small isolated bodies of water and needs to be accompanied by a monitoring program in order to evaluate the results and minimize hazards.

scholarly journals Transfer of Antibiotic Resistance Marker Genes between Lactic Acid Bacteria in Model Rumen and Plant Environments

2009 ◽  
Vol 75 (10) ◽  
pp. 3146-3152 ◽  
Author(s):  
Niamh Toomey ◽  
�ine Monaghan ◽  
S�amus Fanning ◽  
Declan Bolton
Keyword(s):  
Antibiotic Resistance ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Marker Genes ◽  
Natural Environments ◽  
In Vivo Models ◽  
Filter Mating ◽  
Mating Method

ABSTRACT Three wild-type dairy isolates of lactic acid bacteria (LAB) and one Lactococcus lactis control strain were analyzed for their ability to transfer antibiotic resistance determinants (plasmid or transposon located) to two LAB recipients using both in vitro methods and in vivo models. In vitro transfer experiments were carried out with the donors and recipients using the filter mating method. In vivo mating examined transfer in two natural environments, a rumen model and an alfalfa sprout model. All transconjugants were confirmed by Etest, PCR, pulsed-field gel electrophoresis, and Southern blotting. The in vitro filter mating method demonstrated high transfer frequencies between all LAB pairs, ranging from 1.8 � 10−5 to 2.2 � 10−2 transconjugants per recipient. Transconjugants were detected in the rumen model for all mating pairs tested; however, the frequencies of transfer were low and inconsistent over 48 h (ranging from 1.0 � 10−9 to 8.0 � 10−6 transconjugants per recipient). The plant model provided an environment that appeared to promote comparatively higher transfer frequencies between all LAB pairs tested over the 9-day period (transfer frequencies ranged from 4.7 � 10−4 to 3.9 � 10−1 transconjugants per recipient). In our test models, dairy cultures of LAB can act as a source of mobile genetic elements encoding antibiotic resistance that can spread to other LAB. This observation could have food safety and public health implications.

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