What Scientists Know About the Causes of Sepsis
Bacterial infections cause most cases of sepsis. However,
viral infections, such as COVID-19 or influenza;
fungal infections; or noninfectious insults, such as
traumatic injury, can also cause sepsis. Normally, the body releases chemical or
protein immune mediators into the blood to combat the infection or insult. If unchecked, those immune mediators trigger widespread
inflammation, blood clots, and leaky blood vessels. As a result, blood flow is impaired, depriving organs of nutrients and oxygen and leading to organ damage.
Noninfectious insults can lead to sepsis because they can activate the body’s immune responses just like infections do. Sometimes, the cause can’t be determined, particularly when it’s a bacterial agent and the patient has received
antibiotics, which kill the bacteria thus making infectious agents no longer detectable.
The people at highest risk of sepsis are infants, children, older adults, and vulnerable people who have underlying medical problems, have concurrent injuries or surgeries, or are taking certain medications. There are also unknown biological characteristics in the body that may increase or decrease a person’s susceptibility to sepsis and cause some people to decline more rapidly while others recover quickly.
NIGMS-Funded Research Advancing Our Understanding of Sepsis
NIGMS funded scientists seek to answer the fundamental and clinical questions that affect multiple organ systems in the body and are key to improving patient care, including:
How can clinicians distinguish different kinds of sepsis? Scientists are searching for faster and more accurate tests to diagnose and classify sepsis during its early stages by studying the activity of
proteins and other biological chemicals in the blood. These markers can give health care providers information on how severe a case of sepsis a patient has, and whether it might progress, which can help them make decisions about treatment.
What patient traits are associated with sepsis? Sepsis is difficult to treat for many reasons, including differences in patient physiology and the many possible underlying causes of the disease. Researchers are looking for molecular markers associated with overall sepsis risk and poor long-term outcomes. With the help of systematic data and sample collection from patients with sepsis, NIGMS scientists are studying why some people develop the disease and respond to certain treatment while others don’t—insight that could lead to improved diagnosis, therapies, and outcomes.
How does the body fight sepsis? Some patients with sepsis resolve inflammation and regain control of their immune response. Certain proteins and other mediators produced by the body are involved in this immune resolution, but it’s unclear why this process breaks down in some patients. Researchers are studying the mechanisms of immune resolution to investigate new therapies that may be useful for controlling sepsis.
How do health care inequities contribute to sepsis outcomes? African American/Black and Latino sepsis patients experience a lower quality of care and higher rates of complications and death when compared to non-Hispanic White patients. NIGMS researchers are developing interventions to address these issues to improve outcomes and drive reductions in inequities.
What causes poor health outcomes in some sepsis survivors? Sepsis can cause illness and death in many ways, even after the underlying trauma or infection and widespread inflammation are under control. Researchers are studying why some recovered patients have a suppressed
immune system that leaves them highly susceptible to future infections and whether the
nervous system has a role in this suppression. Sepsis can also result in lung injury, muscle wasting, cognitive dysfunction, and impaired blood production.