Related Experiment Videos
Septicaemia caused by phenotypic variants of group A streptococci
P Geslin1, P Kriz-Kuzemenska, A Frémaux
1Centre National de Référence des Pneumocoques, Centre Hospitalier Intercommunal de Créteil, France.
Abstract:
Clinical isolates (115) of Streptococcus pyogenes responsible for septicaemia were investigated to determine whether invasiveness may be correlated with a large variety of strains, or concerns only particular phenotypes. Irrespective of their clinical origin, the strains studied displayed seven of the ten biotypes described within this species. As already observed in a series of strains isolated from pharyngitis, a restricted association between M-types and biotypes was demonstrated; each M-type corresponded to a sole biotype. However, the proportion of biotypes 3, 5 and 7 was higher in the septicaemia series than in the pharyngitis series, with a larger variety of M-types and with more non-typable strains. Despite these differences, the restricted associations between these characters were concordant in both series. These results demonstrate that streptococcal septicaemias appear to be caused by a wide variety of strains, suggesting that multiple factors may be involved in the invasiveness of the bloodstream during streptococcal infections.
Insights
Streptococcus pyogenes causing septicaemia involves diverse strains and M-types, not just specific phenotypes. This suggests multiple factors contribute to bloodstream invasiveness in streptococcal infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Bacteriology
Background:
- Streptococcus pyogenes is a significant pathogen causing various infections, including invasive septicaemia.
- Understanding the characteristics of invasive strains is crucial for managing streptococcal infections.
Purpose of the Study:
- To investigate the correlation between strain diversity and invasiveness in clinical isolates of Streptococcus pyogenes causing septicaemia.
- To compare the phenotypic characteristics of septicaemia isolates with those from pharyngitis.
Main Methods:
- Analysis of 115 clinical isolates of Streptococcus pyogenes from septicaemia cases.
- Biotype characterization and M-typing of the isolates.
- Comparison of strain characteristics between septicaemia and pharyngitis isolates.
Main Results:
- Seven of ten described biotypes were observed in the septicaemia strains.
- A restricted association was found between M-types and biotypes, with each M-type corresponding to a single biotype.
- Biotype proportions (3, 5, 7) were higher in septicaemia isolates compared to pharyngitis isolates, with greater M-type variety and more non-typable strains in the septicaemia group.
Conclusions:
- Streptococcal septicaemia is associated with a wide variety of Streptococcus pyogenes strains.
- Multiple factors likely contribute to the invasiveness of Streptococcus pyogenes in bloodstream infections.
- Phenotypic characteristics, including M-type and biotype, show consistent associations but differ in proportion between invasive and non-invasive disease presentations.