A research led by the Carlos III Health Institute (ISCIII) within the framework of the Center for Biomedical Research Network (CIBER), and in which the Microbiology Service of the Bellvitge Hospital (HUB) has participated, has analysed the causes of the increase in cases of serotype 8 in both the pediatric and adult population in Spain. The study reveals that this serotype has become one of the main causes of invasive pneumococcal disease in Spain, both in adults and in the pediatric population. The increase is due to a specific lineage, CC53/GPSC3, which has characteristics that favor its invasive potential.
The research has been carried out by the National Center for Microbiology (CNM) of the ISCIII and by groups of the CIBER, an entity attached to the ISCIII. Specifically, the team of authors is part of the Pneumococcal Reference Laboratory of the CNM-ISCIII and of the areas of Respiratory Diseases (CIBERES) and Epidemiology and Public Health (CIBERESP) of the CIBER-ISCIII. Within the framework of collaboration, the work has been reinforced by a short stay carried out by one of the ISCIII researchers at the HUB funded by CIBERES in order to carry out the genomic analysis of the bacteria. In addition to the HUB, researchers from the Margarita Salas Biological Research Center of the CSIC and researchers from the Epidemiology of Bacterial Infections group of IDIBELL also participate.
The bacteria responsible
Pneumococcus (Streptococcus pneumoniae) is a bacterium that can cause mild infections, such as otitis or sinusitis, to severe forms such as pneumonia, meningitis or sepsis. These invasive diseases mainly affect children, the elderly or people with risk conditions, and their prevention is based on conjugate vaccines. The work, published in the journal Emerging Microbes & Infections, provides a better understanding of the evolution of the infection thanks to an analysis of 15 years of surveillance (2009-2023) that includes the genomic characterization of clinical isolates and functional studies of interaction between the pathogen and the host.
“The results show how the CC53/GPSC3 lineage has displaced the others thanks to its competitive advantage, which would explain the rebound in cases by serotype 8 after the introduction of pneumococcal conjugate vaccines,” explain José Yuste and Julio Sempere, coordinators of the study and researchers from the CNM-ISCIII and CIBER-ISCIII.
The authors also detail that the success of this CC53/GPSC3 lineage “is due to several properties, such as better adhesion to lung cells, greater biofilm formation and its ability to evade the immune system, which gives it a high capacity for infection, as we have observed in experimental models”.
The research has made it possible to detect two different morphologies of this serotype in culture, which suggests a remarkable biological versatility. The results indicate that non-mucoid variants, although less able to evade the immune system, show greater adherence to human cells, which also contributes to their spread.
The research team concludes: “The study highlights the importance of this serotype in Spain, which is also the main cause of invasive pneumococcal disease in other countries around the world. It is important to continue the exhaustive surveillance of this serotype, in order to check if the new vaccine formulations that include it will be able to mitigate the linked disease”.
The Bellvitge Biomedical Research Institute (IDIBELL) is a research centre created in 2004 and specialising in cancer, neuroscience, translational medicine and regenerative medicine. It has a team of more than 1,500 professionals who, from 73 research groups, publish more than 1,400 scientific articles a year. L’IDIBELL is participated by the Bellvitge University Hospital and the Viladecans Hospital of the Catalan Health Institute, 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 d’Excelencia Internacional 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).