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Negative interactions and virulence differences drive the dynamics in multispecies bacterial infections
Désirée A Schmitz1, Richard C Allen1, Rolf Kümmerli1
1Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland.
Proceedings. Biological Sciences
|July 26, 2023
Summary
In polymicrobial bacterial infections, the most virulent pathogen dictates host mortality, regardless of the number of species present. Targeting the most virulent pathogen is key to reducing disease severity.
Area of Science:
- Microbiology
- Infectious Diseases
- Ecology
Background:
- Polymicrobial bacterial infections involve complex interactions between pathogens and hosts.
- Understanding pathogen-pathogen ecological dynamics is crucial for predicting disease outcomes.
- Limited knowledge exists on how microbial interactions influence virulence and host survival.
Purpose of the Study:
- To investigate the ecological dynamics of polymicrobial infections in a model host.
- To determine how pathogen combinations and numbers affect host mortality and virulence.
- To identify key factors driving outcomes in mixed bacterial infections.
Main Methods:
- Co-infection of *Galleria mellonella* larvae with one to four opportunistic human pathogens.
- Assessment of host mortality and pathogen growth dynamics.
- Experimental validation of treatment strategies targeting the most virulent species.
Main Results:
- Host mortality was consistently determined by the most virulent bacterial species present.
- More virulent pathogens often outcompeted or suppressed less virulent ones in co-infections.
- A positive correlation was observed between a pathogen's in-host growth, competitiveness, and virulence.
Conclusions:
- Virulence in polymicrobial infections is dominated by the most aggressive pathogen.
- Pathogen interactions within the host favor more competitive and virulent species.
- Therapeutic strategies for polymicrobial infections should prioritize targeting the most virulent pathogens to mitigate host morbidity.
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