A study led by IDIBELL and Bellvitge Hospital has focused on a phenomenon that requires attention: the increase in severe cases of infection by Streptococcus dysgalactiae subsp. equisimilis (SDSE), a bacterium that normally lives with us, but that can cause dangerous infections in people with weakened immune systems.
The research, published in the International Journal of Infectious Diseases, has analysed more than 100 cases registered between 2012 and 2022 and reveals that this infection mainly affects elderly people and patients with diseases such as diabetes, cardiovascular pathologies or cancer. In addition, it has been found that some strains of the bacterium are acquiring resistance to antibiotics, a fact that can complicate treatment.
According to Dra. Carmen Ardanuy, head of the Microbiology Service at Bellvitge Hospital, and principal investigator of the research group in Epidemiology of bacterial infections at IDIBELL, as well as the CIBER for Respiratory Diseases (CIBERES), “this increase in infections is not an isolated event but is also being observed in other countries. We need to deepen the research to better understand their evolution and prevent the spread of the most virulent and resistant strains.”
A study with international collaboration
This research, which is part of a project funded by the Carlos III Health Institute, has involved the participation of several Spanish hospitals, such as the Gregorio Marañón General University Hospital (Madrid), the Donostia University Hospital (Basque Country), the Parc Taulí Health Corporation Consortium and the Bellvitge University Hospital (Catalonia). Research teams from France (University of Lorraine) and the United States (Houston Methodist Hospital) have also collaborated.
The team of researchers has used advanced genomic sequencing techniques to analyse the most frequent variants of the bacterium, identifying the clonal complexes CC15, CC17 and CC20 as the most prevalent. In addition, in experimental studies with animal models, it has been observed that one of these variants (CC20-stG62647) has a greater capacity to cause serious diseases.
What does this mean for the population?
Severe cases of Streptococcus dysgalactiae infection mainly affect people over 70 years of age and patients with chronic diseases, who have a more vulnerable immune system. This bacterium is part of the microbiota of many people and, under normal conditions, does not cause problems; but when defences are low or there is a wound, it can trigger serious infections.
In addition, treatment is complicated because macrolides, antibiotics usually used as a second option, have ceased to be effective in many cases. On the other hand, alternatives such as linezolid or delafloxacin have shown more efficacy against this infection.
A call for vigilance and investigation
This study highlights the need to continue monitoring this emerging bacterium and strengthen research to prevent it from becoming a major threat to public health. The research team calls for strengthening detection and surveillance systems, especially in hospitals and health centres where this type of infection can have serious consequences.
According to Guillem López de Egea, first author of the article, “this work is an important step in understanding how Streptococcus dysgalactiae evolves and what tools we have to deal with it. But we still have a lot of research to do to be able to stop its expansion.”
About IDIBELL
The Bellvitge Biomedical Research Institute (IDIBELL) is a research centre in Recruitment created in 2004. It is participated by the Bellvitge University Hospital and the Viladecans Hospital of the Catalan Institute of Health, the Catalan Institute of Oncology, the University of Barcelona and the City Council of L’Hospitalet de Llobregat.
IDIBELL is a member of the Campus of International Excellence of the University of Barcelona HUBc and is part of the CERCA institution of the Generalitat de Catalunya. In 2009 it became one of the first five Spanish research centres accredited as a health research institute by the Carlos III Health Institute. In addition, it is part of the “HR Excellence in Research” program of the European Union and is a member of EATRIS and REGIC. Since 2018, IDIBELL has been an Accredited Centre of the AECC Scientific Foundation (FCAECC).
About Bellvitge University Hospital (HUB)
Bellvitge Hospital is a public, university, research and innovative hospital. With 5,200 expert and committed professionals, it is the local hospital for the citizens of L’Hospitalet and El Prat del Llobregat, and a reference centre of maximum complexity for 2 million people, the entire southern axis of Catalonia. It is the Catalan health centre that performs the most complex surgery, especially oncological surgery, and the centre that performs the most kidney and heart transplants in adults. It integrates in its projects the orientation to improve the patient experience and networking with primary care and the surrounding hospitals. Oriented towards personalised medicine, it has the best genetic diagnosis and imaging tools for cancer and rare diseases that are complemented by the new High Precision Diagnostic Centre, which has the first PET/Magnetic Resonance Imaging in the Spanish healthcare network. It registers about 20,000 major surgery operations annually; 37,000 discharges; 485,000 outpatient visits and about 100,000 diagnostic tests.