Differences in circulating levels of non-classical monocytes and associated caspase 1 activation during Staphylococcus aureus and Escherichia coli bacteremia

@article{courjon2026differences,
  title = {{Differences in circulating levels of non-classical monocytes and associated caspase 1 activation during Staphylococcus aureus and Escherichia coli bacteremia}},
  author = {Johan Courjon and Renaud Scussel and Eva Mellan and Romain Lotte and Raymond Ruimy and Elisa Demonchy and Karine Risso and Irit Touitou and Pierre-Marie Bertrand and Philippe de Swart and Alexandre Robert and Julie Contenti and Jean Dellamonica and Mathieu Jozwiak and Géraldine Gonfrier and Patrick Munro and Anne Doye and Céline Loubatier and Orane Visvikis and Paul Chaintreuil and Arnaud Jacquel and Océane Dufies and Michel Carles and Laurent Boyer},
  journal = {Virulence},
  year = {2026},
  month = nov,
  doi = {10.1080/21505594.2026.2730393},
  url = {https://doi.org/10.1080/21505594.2026.2730393},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Differences in circulating levels of non-classical monocytes and associated caspase 1 activation during Staphylococcus aureus and Escherichia coli bacteremia
AU  - Johan Courjon
AU  - Renaud Scussel
AU  - Eva Mellan
AU  - Romain Lotte
AU  - Raymond Ruimy
AU  - Elisa Demonchy
AU  - Karine Risso
AU  - Irit Touitou
AU  - Pierre-Marie Bertrand
AU  - Philippe de Swart
AU  - Alexandre Robert
AU  - Julie Contenti
AU  - Jean Dellamonica
AU  - Mathieu Jozwiak
AU  - Géraldine Gonfrier
AU  - Patrick Munro
AU  - Anne Doye
AU  - Céline Loubatier
AU  - Orane Visvikis
AU  - Paul Chaintreuil
AU  - Arnaud Jacquel
AU  - Océane Dufies
AU  - Michel Carles
AU  - Laurent Boyer
PY  - 2026
DA  - 2026/11/01
JO  - Virulence
DO  - 10.1080/21505594.2026.2730393
UR  - https://doi.org/10.1080/21505594.2026.2730393
AB  - Bloodstream infections (BSI) caused by Escherichia coli and Staphylococcus aureus are frequent and are associated with substantial mortality rate. The host immune response major determinant of the clinical outcomes during BSI. Here, we investigated the innate immune response, by characterizing peripheral blood myeloid cell subsets and caspase-1 activation as a surrogate marker of inflammasome activation in patients with E. coli or S. aureus bacteremia. We prospectively enrolled patients with monomicrobial bacteremia and analyzed peripheral blood samples by flow cytometry. We observed distinct alterations in myeloid cell composition and caspase-1 activation associated with E. coli bacteremia, including an expansion in intermediate and non-classical monocytes, and increased caspase-1 activation in non-classical monocytes. In contrast, these changes were not observed in patients with S. aureus bacteremia. Additionally, we found differences in myeloid cell subset frequencies and caspase-1 activation between patients with and without sepsis, revealing distinct profiles associated with disease severity. Importantly, the differences in myeloid cell subsets and caspase-1 activation between E. coli and S. aureus bacteremia were primarily attributable to the infecting bacteria rather than disease severity. Furthermore, our findings suggest that eosinophil counts, and caspase-1 activation may serve as potential markers to distinguish between bacterial BSI and viral infections. Overall, our study highlights the importance of considering both the infecting pathogen and disease severity when studying the host immune response during bacteremia and suggests that potential innate immune biomarkers may improve the diagnosis and clinical management of BSI.
SN  - 2150-5594
SN  - 2150-5608
ER  -