Summary auto-generated
This study evaluated whole-cell protein electrophoresis as a method for identifying viridans streptococci species. Researchers analyzed 100 reference strains representing multiple phylogenetic lineages of viridans streptococci using one-dimensional protein electrophoresis. Strains were grown under microaerobic conditions, and proteins were separated by PAGE, with results analyzed using cluster analysis. The method successfully differentiated most viridans streptococcal species, with strains showing similar protein patterns correlating with known DNA-DNA hybridization data. The analysis strongly supported classifying members of the Streptococcus anginosus group (S. anginosus, S. constellatus, and S. intermedius) as a single species, as they formed one heterogeneous but undivided protein cluster. The findings also revealed significant heterogeneity within S. mitis biovar 2, with individual strains clustering with different species including S. oralis, S. cristatus, and S. parasanguinis, suggesting biovar 2 represents multiple distinct species rather than a single taxon. The protein electrophoretic approach proved reliable and useful for streptococcal identification in clinical laboratories.
Key findings
- Whole-cell protein electrophoresis successfully differentiated most viridans streptococcal species with high reproducibility (≥94% inter-run similarity)
- S. mitis biovar 2 is heterogeneous, with different strains clustering with S. oralis, S. cristatus, and S. parasanguinis rather than forming a cohesive group
- The S. anginosus group (S. anginosus, S. constellatus, and S. intermedius) formed a single protein electrophoretic cluster, supporting their classification as one species
- Protein electrophoresis results correlated with available DNA-DNA hybridization data, validating the method for species-level identification
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Abstract
One hundred reference strains representing all species belonging to the different phylogenetic lineages of the viridans streptococci were examined by means of one-dimensional whole-organism protein electrophoresis. For most of the species examined, multiple strains characterized by DNA-DNA hybridization were included and, wherever described, representatives of different biochemical variants were analysed. Most species were clearly differentiated. The data support the viewpoint that members of the Streptococcus anginosus group constitute a single species and indicate that Streptococcus mitis biovar 2 is a heterogeneous taxon comprising strains from several streptococcal species.