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Genomic differences in Streptococcus pyogenes serotype M3 between recent isolates associated with toxic shock-like
Y Inagaki1, F Myouga, H Kawabata
1Department of Bacteriology, National Institute of Infectious Diseases, Tokyo and Division of Gene Expression and Regulation 1, National Institute for Basic Biology, Okazaki, Japan.
Abstract:
Genomic differences among past Streptococcus pyogenes serotype M3 strains isolated in 1973 and before from patients with streptococcal pharyngitis, recent (1990s) serotype M3 clinical isolates from patients with pharyngitis, and recent M3 isolates from patients with toxic shock-like syndrome were investigated by restriction landmark genomic scanning and by modified random-amplified polymorphic DNA-polymerase chain reaction. Similar polymorphic DNA fragments were identified between the older M3 isolates and the recent isolates; also, the recent M3 clinical isolates from patients with pharyngitis were genetically indistinguishable, by the methods used, from the M3 isolates of patients with toxic shock-like syndrome. Although nucleotide sequences of these regions showed no apparent homology with known virulence factors, the DNA fragments could distinguish the recent M3 strains from the past strains. These results suggested that the recent strains have emerged because of genetic divergence.
Insights
Recent Streptococcus pyogenes M3 strains show genetic divergence from older strains. These newer strains, linked to pharyngitis and toxic shock-like syndrome, are genetically indistinguishable from each other.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Streptococcus pyogenes serotype M3 strains have been associated with various infections, including streptococcal pharyngitis and toxic shock-like syndrome.
- Understanding genomic variations in M3 strains is crucial for tracking pathogen evolution and virulence.
Purpose of the Study:
- To investigate the genomic differences between historical (pre-1973) and recent (1990s) Streptococcus pyogenes M3 strains.
- To compare the genetic profiles of recent M3 isolates from pharyngitis patients with those from toxic shock-like syndrome patients.
Main Methods:
- Restriction landmark genomic scanning (RLGS).
- Modified random-amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR).
Main Results:
- Similar polymorphic DNA fragments were found between older and recent M3 isolates.
- Recent M3 isolates from pharyngitis and toxic shock-like syndrome were genetically indistinguishable using the employed methods.
- Distinct DNA fragments differentiated recent M3 strains from past strains, despite no homology to known virulence factors.
Conclusions:
- Recent Streptococcus pyogenes M3 strains have emerged due to genetic divergence.
- The genetic similarity between recent pharyngitis and toxic shock-like syndrome M3 isolates suggests a common evolutionary path or shared genetic traits contributing to virulence.