The coagulation system and bacterial infections: A double-edged sword of host defense and pathogen evasion

The body's coagulation system is best known for stopping bleeding, but during bacterial infections, it plays a much more complex role. On one hand, it helps trap and isolate bacteria by forming clots that prevent their spread, a frontline defense strategy known as immunothrombosis. On the other hand, many bacteria have learned to hijack this very system to their advantage. Some trigger clot formation to shield themselves from immune cells, while others dissolve clots to escape and invade new tissues. This review looks at how key pathogens, including Staphylococcus aureus, Streptococcus pyogenes, and Escherichia coli, interact with and manipulate the host's coagulation system. These microbial mechanisms can worsen infections and lead to serious complications like sepsis, blood clots, organ damage, and even death. By unpacking the delicate balance between protection and harm, we aim to highlight why understanding these interactions matters, not just for basic science, but also for improving how we diagnose and treat infection-related clotting disorders.