scholarly journals FITNESS BENEFITS TO BACTERIA OF CARRYING PROPHAGES AND PROPHAGE-ENCODED ANTIBIOTIC-RESISTANCE GENES PEAK IN DIFFERENT ENVIRONMENTS

2020 ◽  
Author(s):  
Carolin C. Wendling ◽  
Dominik Refardt ◽  
Alex R. Hall
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Costs And Benefits ◽  
Prophage Induction ◽  
Resistance Evolution ◽  
Bacterial Chromosomes ◽  
Bacterial Fitness ◽  
Fitness Benefits ◽  
Free Strains

AbstractBacteria can acquire antibiotic resistance genes (ARGs) via prophages, phage genomes integrated into bacterial chromosomes. Such prophages may influence bacterial fitness via increased antibiotic resistance, protection from further phage infection, or by switching to a lytic lifecycle that releases free phages which can infect phage-susceptible competitors. We expect these effects to depend on environmental conditions because of, for example, environment-dependent induction of the lytic lifecycle. However, our understanding of how costs and benefits of prophage-encoded ARGs vary across environments remains limited. Here, by studying prophages with and without ARGs in Escherichia coli, we distinguished between effects of prophages alone and ARGs they carry. In competition with prophage-free strains, fitness benefits from prophages and ARGs peaked in different environments. Prophage carriage was most beneficial in conditions where induction of the lytic lifecycle was common, whereas ARGs were more beneficial in the presence of antibiotics and when prophage induction was lower. Acquisition of prophage-encoded ARGs by competing phage-susceptible strains was most common when prophage induction, and therefore the amount of free phages, was high. Thus, selection on prophages and ARGs varies independently across environments, which is important for predicting the spread of mobile/integrating genetic elements and their role in antibiotic resistance evolution.

GENERAL PRINCIPLES OF ANTIBIOTIC RESISTANCE EVOLUTION IN BACTERIA (REVIEW OF LITERATURE)

2020 ◽  
Vol 65 (6) ◽  
pp. 387-393
Author(s):  
N. V. Davidovich ◽  
Natalya Nilolaevna Kukalevskaya ◽  
E. N. Bashilova ◽  
T. A. Bazhukova
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Molecular Genetic ◽  
Antibiotic Resistance Genes ◽  
Human Pathogens ◽  
Intrinsic Resistance ◽  
Resistance Evolution ◽  
Genes Encoding ◽  
The Impact

Currently, the impact of antibiotic resistance on human health is a worldwide problem and its study is of great interest from a molecular genetic, environmental and clinical view-point. This review summarizes the latest data about antibiotic resistance, the classification of microorganisms as sensitive and resistant to the action of antibiotics, reveals the concept of minimum inhibitory concentration from modern positions. The resistance of microorganisms to antibacterial agents can be intrinsic and acquired, as well as being one of the examples of evolution that are currently available for study. Modern methods of whole-genome sequencing and complex databases of nucleotide-tagged libraries give an idea of the multifaceted nature of the mechanisms of intrinsic resistance to antibiotics and are able to provide information on genes encoding metabolic enzymes and proteins that regulate the basic processes of the physiology of bacteria. The article describes the main ways of spreading the resistance of microorganisms, reflects the concepts of “founder effect” and the fitness cost of bacteria, which underlie the emergence and evolution of antibiotic resistance. It is shown that the origin of antibiotic resistance genes that human pathogens currently possess can be traced by studying the surrounding not only clinical, but also non-clinical (ecological) habitats. As well as microorganisms of the surrounding ecosystems are the donors of resistance genes in horizontal gene transfer.

scholarly journals Antibiotics in Feed Induce Prophages in Swine Fecal Microbiomes

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
Heather K. Allen ◽  
Torey Looft ◽  
Darrell O. Bayles ◽  
Samuel Humphrey ◽  
Uri Y. Levine ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Antibiotic Resistance ◽  
Gene Transfer ◽  
Resistance Genes ◽  
Bacterial Communities ◽  
Antibiotic Resistance Genes ◽  
Ecosystem Dynamics ◽  
Prophage Induction ◽  
Collateral Effects ◽  
Collateral Effect

ABSTRACTAntibiotics are a cost-effective tool for improving feed efficiency and preventing disease in agricultural animals, but the full scope of their collateral effects is not understood. Antibiotics have been shown to mediate gene transfer by inducing prophages in certain bacterial strains; therefore, one collateral effect could be prophage induction in the gut microbiome at large. Here we used metagenomics to evaluate the effect of two antibiotics in feed (carbadox and ASP250 [chlortetracycline, sulfamethazine, and penicillin]) on swine intestinal phage metagenomes (viromes). We also monitored the bacterial communities using 16S rRNA gene sequencing. ASP250, but not carbadox, caused significant population shifts in both the phage and bacterial communities. Antibiotic resistance genes, such as multidrug resistance efflux pumps, were identified in the viromes, but in-feed antibiotics caused no significant changes in their abundance. The abundance of phage integrase-encoding genes was significantly increased in the viromes of medicated swine over that in the viromes of nonmedicated swine, demonstrating the induction of prophages with antibiotic treatment. Phage-bacterium population dynamics were also examined. We observed a decrease in the relative abundance ofStreptococcusbacteria (prey) whenStreptococcusphages (predators) were abundant, supporting the “kill-the-winner” ecological model of population dynamics in the swine fecal microbiome. The data show that gut ecosystem dynamics are influenced by phages and that prophage induction is a collateral effect of in-feed antibiotics.IMPORTANCEThis study advances our knowledge of the collateral effects of in-feed antibiotics at a time in which the widespread use of “growth-promoting” antibiotics in agriculture is under scrutiny. Using comparative metagenomics, we show that prophages are induced by in-feed antibiotics in swine fecal microbiomes and that antibiotic resistance genes were detected in most viromes. This suggests that in-feed antibiotics are contributing to phage-mediated gene transfer, potentially of antibiotic resistance genes, in the swine gut. Additionally, the so-called “kill-the-winner” model of phage-bacterium population dynamics has been shown in aquatic ecosystems but met with conflicting evidence in gut ecosystems. The data support the idea that swine fecalStreptococcusbacteria and their phages follow the kill-the-winner model. Understanding the role of phages in gut microbial ecology is an essential component of the antibiotic resistance problem and of developing potential mitigation strategies.

scholarly journals Negative frequency dependent selection on plasmid carriage and low fitness costs maintain extended spectrum β-lactamases in Escherichia coli

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tatiana Dimitriu ◽  
Frances Medaney ◽  
Elli Amanatidou ◽  
Jessica Forsyth ◽  
Richard J. Ellis ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Selection Pressure ◽  
Culture Media ◽  
Antibiotic Resistance Genes ◽  
Direct Selection ◽  
Frequency Dependent ◽  
Extended Spectrum ◽  
Fitness Benefits ◽  
M 14

AbstractPlasmids may maintain antibiotic resistance genes in bacterial populations through conjugation, in the absence of direct selection pressure. However, the costs and benefits of conjugation for plasmid and bacterial fitness are not well understood. Using invasion and competition experiments with plasmid mutants we explicitly tested how conjugation contributes to the maintenance of a plasmid bearing a single extended-spectrum ß-lactamase (ESBL) gene (blaCTX-M-14). Surprisingly, conjugation had little impact on overall frequencies, although it imposed a substantial fitness cost. Instead, stability resulted from the plasmid conferring fitness benefits when rare. Frequency dependent fitness did not require a functional blaCTX-M-14 gene, and was independent of culture media. Fitness benefits when rare are associated with the core plasmid backbone but are able to drive up frequencies of antibiotic resistance because fitness burden of the blaCTX-M-14 gene is very low. Negative frequency dependent fitness can contribute to maintaining a stable frequency of resistance genes in the absence of selection pressure from antimicrobials. In addition, persistent, low cost resistance has broad implications for antimicrobial stewardship.

Quintuplex PCR to Detect Antibiotic Resistance Genes in Streptococcus pneumoniae

2016 ◽  
Vol 1 (2) ◽  
pp. 22 ◽  
Author(s):  
Navindra Kumari Palanisamy ◽  
Parasakthi Navaratnam ◽  
Shamala Devi Sekaran
Keyword(s):  
Antibiotic Resistance ◽  
Streptococcus Pneumoniae ◽  
Resistance Genes ◽  
Bacterial Pathogen ◽  
Antibiotic Resistance Genes ◽  
Pcr Amplification ◽  
Penicillin Resistance ◽  
Penicillin Binding Proteins ◽  
Efflux Mechanism ◽  
Mic Value

Introduction: Streptococcus pneumoniae is an important bacterial pathogen, causing respiratory infection. Penicillin resistance in S. pneumoniae is associated with alterations in the penicillin binding proteins, while resistance to macrolides is conferred either by the modification of the ribosomal target site or efflux mechanism. This study aimed to characterize S. pneumoniae and its antibiotic resistance genes using 2 sets of multiplex PCRs. Methods: A quintuplex and triplex PCR was used to characterize the pbp1A, ermB, gyrA, ply, and the mefE genes. Fifty-eight penicillin sensitive strains (PSSP), 36 penicillin intermediate strains (PISP) and 26 penicillin resistance strains (PRSP) were used. Results: Alteration in pbp1A was only observed in PISP and PRSP strains, while PCR amplification of the ermB or mefE was observed only in strains with reduced susceptibility to erythromycin. The assay was found to be sensitive as simulated blood cultures showed the lowest level of detection to be 10cfu. Conclusions: As predicted, the assay was able to differentiate penicillin susceptible from the non-susceptible strains based on the detection of the pbp1A gene, which correlated with the MIC value of the strains.

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