Gram-stained smear of streptococci. Credit: Graham Beards
If you know one person—or 10—that had strep this winter/early spring, you’re not alone. Strep infections are increasing not only in the U.S., but worldwide.
On the heels of these last few infectious months, scientists at Houston Methodist discovered that fast‑rising Streptococcus dysgalactiae subspecies equisimilis (SDSE) comes in more forms than expected, including ones that may lead to life-threatening infections.
According to the study, published in Microbiology Spectrum, using whole-genome sequencing to analyze more than 800 patient samples, the researchers discovered 44 distinct variants of the bacterium, an insight older testing methods did not provide.
Specifically, the team discovered that certain strains caused specific types of infection. For example, one type of strain was associated with skin infections, while another type was associated with blood infections and yet another was associated with throat infections.
“This is the first time we’ve seen such strong associations between strains and specific infections across a large patient population,” said first author, Lydia Pouga, research scientist at Houston Methodist.
Pouga said the study provides critical genetic data to understand how the bacterium spreads, changes and causes infections. This information will help deliver insights that can improve diagnosis, infection control and future vaccine planning.
The study is the largest in the U.S. to investigate SDSE at this level. The bacterium is most closely related to the flesh-eating Group A Strep, which causes illnesses ranging from mild strep throat and fever to severe conditions like blood infections and necrotizing fasciitis. SDSE was originally considered rare and was believed to mostly infect people who already had other health issues.
James Musser’s lab at Houston Methodist is renowned for using an integrated interdisciplinary research approach to unravel new information about infections caused by group A Streptococcus (GAS), which is responsible for more than 700 million cases of human disease each year globally.
Data from Houston Methodist