This 2019 Swiss rodent study investigated immune responses to five types of bacterial infections:
“The innate immune system recalls a challenge to adapt to a secondary challenge, a phenomenon called trained immunity. Trained immunity protected mice from a large panel of clinically relevant bacterial pathogens inoculated systematically and locally to induce peritonitis, enteritis and pneumonia.
Induction of trained immunity remodeled bone marrow and blood cellular compartments, providing efficient barriers against bacterial infections. Protection was remarkably broad when considering the pathogens and sites of infection tested.
We are running experiments to delineate the length of protection conferred by trained immunity. Trained immunity is most typically induced with β-glucan.
Mice were injected with methicillin-resistant Staphylococcus aureus (MRSA). Trained mice survived better than control mice (31% vs. 0% survival) and had 10-fold less bacteria in blood 2 days post-infection.
Mice were challenged with a lethal dose of Listeria monocytogenes. Most strikingly, all trained mice survived infection while all control mice died within 5 days. Bacteria were not detected in blood collected from trained mice 2 and 3 days post-infection.”
https://academic.oup.com/jid/advance-article/doi/10.1093/infdis/jiz692/5691195 “Trained immunity confers broad-spectrum protection against bacterial infections”
One of the coauthors also published: