Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.

Competition plays a key role in shaping the structure and diversity of bacterial populations. In many clinically important bacterial species, strains compete at multiple scales: at the between-host scale for new hosts to colonise, and at the within-host scale during co-colonisation. Characterising t...

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Main Authors: Aswin Krishna, Gerry Tonkin-Hill, Thibaut Morel-Journel, Stephen Bentley, Paul Turner, François Blanquart, Sonja Lehtinen
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-08-01
Series:PLoS Biology
Online Access:https://doi.org/10.1371/journal.pbio.3003300
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author Aswin Krishna
Gerry Tonkin-Hill
Thibaut Morel-Journel
Stephen Bentley
Paul Turner
François Blanquart
Sonja Lehtinen
author_facet Aswin Krishna
Gerry Tonkin-Hill
Thibaut Morel-Journel
Stephen Bentley
Paul Turner
François Blanquart
Sonja Lehtinen
author_sort Aswin Krishna
collection DOAJ
description Competition plays a key role in shaping the structure and diversity of bacterial populations. In many clinically important bacterial species, strains compete at multiple scales: at the between-host scale for new hosts to colonise, and at the within-host scale during co-colonisation. Characterising these multiple facets of competition plays an important role in understanding bacterial ecology. This is particularly relevant for antibiotic resistance, where competition between antibiotic-susceptible and resistant strains determines resistance dynamics. In this work, we perform survival analyses on a large longitudinal dataset of Streptococcus pneumoniae carriage to quantify how within-host competition affects the rates of clearance and establishment of pneumococcal strains. We find that the presence of a within-host competitor is associated with a 33% increase in clearance and a 54% reduction in establishment. Priority effects and serotype differences partially predict the outcomes of this within-host competition. Further, we quantify the effects of antibiotic resistance on between- and within-host components of fitness. Antibiotic consumption is associated with increased clearance rate for both susceptible and resistant strains, albeit to a higher extent in susceptible strains. In the absence of antibiotics, we find some evidence that resistance is associated with increased susceptibility to within-host competition, suggesting a fitness cost of resistance. Overall, our work provides quantitative insights into pneumococcal competition across scales and the role of this competition in shaping pneumococcal epidemiology.
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spelling doaj-art-5b651b788f2f49c8800dbe9c3b2c37f42025-08-20T03:40:21ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852025-08-01238e300330010.1371/journal.pbio.3003300Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.Aswin KrishnaGerry Tonkin-HillThibaut Morel-JournelStephen BentleyPaul TurnerFrançois BlanquartSonja LehtinenCompetition plays a key role in shaping the structure and diversity of bacterial populations. In many clinically important bacterial species, strains compete at multiple scales: at the between-host scale for new hosts to colonise, and at the within-host scale during co-colonisation. Characterising these multiple facets of competition plays an important role in understanding bacterial ecology. This is particularly relevant for antibiotic resistance, where competition between antibiotic-susceptible and resistant strains determines resistance dynamics. In this work, we perform survival analyses on a large longitudinal dataset of Streptococcus pneumoniae carriage to quantify how within-host competition affects the rates of clearance and establishment of pneumococcal strains. We find that the presence of a within-host competitor is associated with a 33% increase in clearance and a 54% reduction in establishment. Priority effects and serotype differences partially predict the outcomes of this within-host competition. Further, we quantify the effects of antibiotic resistance on between- and within-host components of fitness. Antibiotic consumption is associated with increased clearance rate for both susceptible and resistant strains, albeit to a higher extent in susceptible strains. In the absence of antibiotics, we find some evidence that resistance is associated with increased susceptibility to within-host competition, suggesting a fitness cost of resistance. Overall, our work provides quantitative insights into pneumococcal competition across scales and the role of this competition in shaping pneumococcal epidemiology.https://doi.org/10.1371/journal.pbio.3003300
spellingShingle Aswin Krishna
Gerry Tonkin-Hill
Thibaut Morel-Journel
Stephen Bentley
Paul Turner
François Blanquart
Sonja Lehtinen
Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
PLoS Biology
title Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
title_full Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
title_fullStr Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
title_full_unstemmed Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
title_short Quantifying the effects of antibiotic resistance and within-host competition on strain fitness in Streptococcus pneumoniae.
title_sort quantifying the effects of antibiotic resistance and within host competition on strain fitness in streptococcus pneumoniae
url https://doi.org/10.1371/journal.pbio.3003300
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