Scientists have discovered a new variant of streptococcal bacteria that has contributed to a rise in disease cases in the UK over the last 17 years. Group A streptococcus causes around 600 million infections annually worldwide. Severe infections can cause necrotising fasciitis, pneumonia, sepsis, or toxic shock, and around 1 in 4 people who suffer an invasive infection do not survive.
Researchers at Imperial College London and clinicians at Imperial College Healthcare NHS Trust, together with colleagues at Public Health England, noticed a sharp rise in infections caused by one particular strain, called emm89, from 1998 to 2009. To investigate why, they sequenced the genomes of bacterial samples from patients.
The genetic sequences revealed a new subtype of emm89 streptococcus whose emergence coincided with the surge in cases.
Japan, Canada, France and Sweden have reported a surge in the same strain type, raising the possibility that the new variant is spreading globally.
The study, published in the journal mBio, was funded by the NIHR Imperial Biomedical Research Centre and the UK Clinical Research Collaboration.