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Interactions between Eikenella corrodens and 'Streptococcus milleri-group' organisms: possible mechanisms of
K A Young1, R P Allaker, J M Hardie
1Department of Oral Microbiology, St. Bartholomew's, London, UK.
Abstract:
Interactions between the 'Streptococcus milleri-group' organisms (SMG; S. intermedius, S. constellatus and S. anginosus) and Eikenella corrodens were investigated. Coaggregation reactions occurred frequently between S. anginosus (83% of strain combinations) or S. constellatus (87%) and E. corrodens isolates, but were infrequent between S. intermedius and E. corrodens (28%). No enhancement of enzyme activities against lipid, phosphate, peptide and saccharide substrates tested were detected with combinations of species in comparison to the species alone. Exponential growth of S. constellatus and S. intermedius, in mixed culture with E. corrodens, occurred within 6h post inoculation, in comparison to 25h without E. corrodens. No growth stimulation of S. anginosus was observed. It is concluded that both coaggregation and growth stimulation occur between E. corrodens and SMG isolates, and may be important mechanisms in the establishment of mixed infections involving these bacteria.
Insights
Interactions between Streptococcus milleri-group (SMG) bacteria and Eikenella corrodens show frequent coaggregation and growth stimulation, particularly with S. constellatus and S. anginosus. These interactions may play a role in establishing mixed bacterial infections.
Area of Science:
- Microbiology
- Bacterial Interactions
- Oral Microbiome
Background:
- The Streptococcus milleri-group (SMG) comprises S. intermedius, S. constellatus, and S. anginosus, often found in mixed infections.
- Eikenella corrodens is another common bacterium implicated in various infections.
Purpose of the Study:
- To investigate the coaggregation and growth interactions between SMG bacteria and Eikenella corrodens.
- To determine if these interactions influence bacterial enzyme activities or growth rates.
Main Methods:
- Coaggregation assays were performed between different SMG species and Eikenella corrodens isolates.
- Bacterial growth rates were monitored in monocultures and co-cultures.
- Enzyme activities against various substrates were assessed in mixed cultures.
Main Results:
- High coaggregation frequencies were observed between E. corrodens and S. anginosus (83%) or S. constellatus (87%), but not S. intermedius (28%).
- Exponential growth of S. constellatus and S. intermedius was significantly faster in co-culture with E. corrodens (6h) compared to monoculture (25h).
- No enhanced enzyme activities were detected in mixed cultures compared to single species.
Conclusions:
- Coaggregation and growth stimulation occur between E. corrodens and specific SMG isolates (S. constellatus, S. intermedius).
- These interactions may be crucial mechanisms facilitating the establishment of polymicrobial infections involving these bacteria.