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Surface hydrophobicity of plasmid-carrying virulent Shigella flexneri and their avirulent variants
Abstract:
Five pairs of strains of S. flexneri each differing in the colour of their colonies after growth on Congo red agar have been tested for their ability to cause keratoconjunctivitis in the guinea pig eye, for the presence of the 140 Md virulence plasmid, for the presence of the virulence marker antigen, and for their ability to adsorb to hydrophobic surfaces (cellulose nitrate filters and Phenyl Sepharose). The results suggest that the presence of the 140 Md virulence plasmid provides the bacterial surface with a rather high degree of hydrophobicity; exceptions have been found.
Insights
The 140 Md virulence plasmid in Shigella flexneri strains enhances bacterial surface hydrophobicity, influencing their ability to cause eye infections. This suggests a link between the plasmid, surface properties, and pathogenicity.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Ocular Infections
Background:
- Shigella flexneri is a significant cause of bacterial dysentery.
- Virulence factors, including plasmids, play a crucial role in bacterial infection.
- The relationship between bacterial surface properties and pathogenicity is an area of ongoing research.
Purpose of the Study:
- To investigate the correlation between the 140 Md virulence plasmid in S. flexneri and bacterial surface hydrophobicity.
- To assess the impact of these factors on the ability of S. flexneri to cause keratoconjunctivitis in a guinea pig model.
- To examine the presence of virulence markers and adsorption to hydrophobic surfaces.
Main Methods:
- Comparative analysis of S. flexneri strains with differing colony colors on Congo red agar.
- Inoculation of guinea pig eyes to assess keratoconjunctivitis development.
- Detection of the 140 Md virulence plasmid using molecular methods.
- Assay for virulence marker antigen presence.
- Measurement of bacterial adsorption to hydrophobic surfaces (cellulose nitrate filters and Phenyl Sepharose).
Main Results:
- The presence of the 140 Md virulence plasmid was strongly associated with increased bacterial surface hydrophobicity.
- A high degree of hydrophobicity was observed in strains possessing the virulence plasmid.
- Exceptions to this correlation were noted, indicating other contributing factors.
- The ability to cause keratoconjunctivitis was evaluated in relation to plasmid presence and hydrophobicity.
Conclusions:
- The 140 Md virulence plasmid significantly contributes to the hydrophobicity of the S. flexneri bacterial surface.
- Bacterial surface hydrophobicity, influenced by the virulence plasmid, may play a role in the pathogenesis of S. flexneri eye infections.
- Further research is needed to elucidate the exceptions and the precise mechanisms linking the plasmid, hydrophobicity, and virulence.