Lorraine Williamson
Spain is seeing a significant rise in serious infections caused by a strain of Streptococcus that is becoming increasingly resistant to antibiotics. A new study conducted by the Hospital de Bellvitge in L’Hospitalet de Llobregat analysed more than 100 cases of Streptococcus dysgalactiae subsp. equisimilis (SDSE) infections recorded between 2012 and 2022.
Published in the International Journal of Infectious Diseases, the findings show a marked increase in cases over the past decade. Researchers warn that this trend presents a growing public health concern, particularly for people with chronic illnesses or weakened immune systems.
What is Streptococcus?
Streptococcus is a genus of bacteria commonly found in the human throat, skin, and intestines. While many strains are harmless, others can cause mild to severe infections. These range from strep throat and skin infections to invasive diseases such as sepsis, pneumonia, and toxic shock syndrome. The SDSE strain is part of the same group but is less well-known and is now drawing attention due to its rising threat.
Infections linked to vulnerable groups
While SDSE is typically a harmless bacterium found in the human gut, it can trigger life-threatening infections in certain individuals. Older adults, people with diabetes, cardiovascular disease, or cancer, and those with open wounds are especially at risk.
Notably, individuals over 70 and those living with long-term conditions appear more likely to develop severe complications. Researchers identified the CC20-stG62647 strain as the most pathogenic during laboratory testing.
Growing antibiotic resistance
One of the most concerning findings is that some SDSE strains no longer respond well to commonly used antibiotics, including macrolides. These drugs, often prescribed for bacterial infections, are proving less effective against SDSE.
However, the study highlights potential alternatives. Linezolid and delafloxacin show greater efficacy and could offer new treatment options for patients with more complex infections.
Call for further research and genome tracking
Scientists at Hospital de Bellvitge used genome sequencing to trace the most common SDSE strains in Spain—identified as CC15, CC17, and CC20. Genome sequencing allows for the detailed analysis of bacterial DNA, helping to identify variations linked to antibiotic resistance and pathogenicity.
Dr Carmen Ardanuy, one of the study’s authors, stressed the need for deeper investigation into how the bacterium is evolving. Without this, it will be difficult to control the spread of more resistant and dangerous strains.
Global rise in SDSE cases
Spain is not alone in facing this challenge. Researchers point to a global increase in serious SDSE infections, underlining the need for coordinated public health responses.
While awareness is growing, the researchers warn that there is still a long way to go. Investment in monitoring systems, faster diagnostic tools, and treatment innovation will be key to reducing the long-term threat posed by SDSE.
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