New genetic mutation linked to highly invasive Streptococcus pyogenes infections

A group of researchers led by The University of Osaka have identified a novel genetic mutation in Streptococcus pyogenes, a common bacterium which causes strep throat, significantly associated with severe invasive infections.

A single mutation in the bacterial ferric ion transporter weakens bacterial growth in human blood. This mutation, unique to Japanese isolates, indicates a novel pathogenic mechanism. This world-first discovery offers a potential new target for treatments and preventive measures.

S. pyogenes causes severe invasive infections with a high mortality rate. Cases of invasive strep in Japan surged in 2024, highlighting the urgent need for new treatments and a deeper understanding of the underlying disease mechanisms.

A new study looked at the genes of hundreds of S. pyogenes samples from Japan and other countries to pinpoint the genetic differences that make some strains more dangerous. The research group conducted a comprehensive genomic analysis of 666 S. pyogenes strains—311 from Japan and 355 from other countries—using cutting-edge pangenome-wide association studies.

The researchers found a number of genetic changes linked to the bacteria's ability to cause severe infections, including a brand new mutation never seen before. This mutation affects a gene involved in how the bacterium gets iron, a nutrient it needs to survive.

Interestingly, they also found that many genes previously thought to cause serious illness were actually common in the less harmful strains. This suggests that some strains may become more dangerous not just by gaining harmful genes, but also by losing genes that hold them back.

This research significantly advances our understanding of severe invasive strep, especially within the Japanese population.

This large-scale analysis, involving painstaking supercomputer analysis and experimental validation, offers a promising avenue for new therapies targeting a mutated iron transporter."

Dr. Masayuki Ono, Study Lead Author and Assistant Professor, Graduate School of Dentistry, Osaka University

The study's pangenome-wide approach also demonstrates the potential of large-scale genomic analyses for unraveling complex disease mechanisms, offering a powerful tool for future research in other infectious diseases.