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Published on: May 1, 2021
The pneumococcus: why a commensal misbehaves
1Department of Microbiology and Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104, USA. weiser@mail.med.upenn.edu
Abstract:
Several characteristics of Streptococcus pneumoniae (pneumococcus) combine to make it a particularly problematic pathogen. Firstly, the pneumococcus has the capacity to cause disease through the expression of virulence factors such as its polysaccharide capsule and pore-forming toxin. In addition, the pneumococcus is highly adaptable as demonstrated by its ability to acquire and disseminate resistance to multiple antibiotics. Although the pneumococcus is a major cause of disease, the organism is most commonly an "asymptomatic" colonizer of its human host (the carrier state), with transmission occurring exclusively from this reservoir of commensal organisms. Thus, it is unclear how the organism's virulence and adaptability promote its persistence or host to host spread during its carrier state. This review summarizes current understanding of how these characteristics may contribute to the commensal lifestyle of the pneumococcus.
Insights
Streptococcus pneumoniae (pneumococcus) possesses virulence factors and adaptability, yet primarily exists as an asymptomatic colonizer. This review explores how these traits support its commensal lifestyle and transmission.
Area of Science:
- Microbiology
- Pathogen Biology
- Epidemiology
Background:
- Streptococcus pneumoniae (pneumococcus) is a significant human pathogen.
- It causes disease via virulence factors like polysaccharide capsule and toxins.
- Pneumococcus exhibits high adaptability, acquiring antibiotic resistance.
Purpose of the Study:
- To review how pneumococcus's virulence and adaptability contribute to its asymptomatic carrier state.
- To understand the persistence and host-to-host spread mechanisms during commensal colonization.
Main Methods:
- Literature review of existing studies on Streptococcus pneumoniae.
- Analysis of virulence factors and antibiotic resistance mechanisms.
- Examination of the relationship between pathogenic traits and commensal behavior.
Main Results:
- Pneumococcus utilizes virulence factors and adaptability for persistence in the human host.
- Transmission occurs primarily from asymptomatic carriers.
- The interplay between virulence and adaptability in the carrier state is complex.
Conclusions:
- Understanding the commensal lifestyle of pneumococcus is crucial for controlling its spread.
- Virulence and adaptability may paradoxically aid pneumococcus's survival as a commensal.
- Further research is needed to elucidate these mechanisms fully.
