What causes sepsis? Diagnosis, prevention, and treatment

Overview: What is sepsis?

Sepsis is a life-threatening condition that can progress into severe sepsis and septic shock. It occurs as an inflammatory response to an infection that becomes out of control, leading to widespread inflammation and possible organ failure. 

Sepsis, sometimes known as septicemia or blood poisoning, can occur due to various types of infections, including bacterial, viral, and fungal infections. Sepsis is a medical emergency that requires immediate medical care and treatment. As sepsis progresses into septic shock, inflammation of the blood vessels can cause the blood vessels to leak, resulting in reduced blood flow and blood pressure. This may eventually lead to organ damage, coma, or death.

What causes sepsis?

Sepsis occurs when the body overreacts to a serious infection, usually a bacterial infection. An infection may trigger an extreme inflammatory response by the immune system, which can lead to inflammation and damage to the organs and tissues. The most common cause of sepsis is bacterial pneumonia, which is also the deadliest cause of sepsis, accounting for around half of sepsis deaths.

Infections can occur in almost any area of the body. However, certain infections may be more likely to lead to sepsis than other infections. Most sepsis cases (80%) are caused by:

• Respiratory infections 

• Gastrointestinal infections

• Urinary tract infections or genital infections

• Soft tissue and skin infections

Other less common causes of sepsis include:

• Bone and joint infections

• Central nervous system infections

Although bacterial infections are the most common type of infection that can trigger sepsis, infections caused by other microorganisms can also lead to sepsis. Viral infections, such as influenza or COVID-19, can also lead to sepsis, although less frequently than bacterial infections. In addition, parasitic and fungal infections can also result in sepsis. However, certain risk factors come into play that can determine the chance of an infection causing sepsis.

RELATED: Pneumonia treatments and medications

Risk factors for sepsis

Some people are more vulnerable to developing sepsis than others. Significant risk factors include:

• Age older than 65 (older adults)

• Age younger than one (babies and newborns)

• Weakened immune system

• Chronic health conditions, such as diabetes, heart disease, or COPD

• Recent surgery or hospitalization

• Invasive medical devices, such as catheters and implants

• Recent treatment with antibiotics

Knowing the risk factors of sepsis could help increase the chances of an early diagnosis and appropriate treatment plan, which can improve outcomes. 

Is sepsis serious? When to see a doctor

Sepsis is a serious and potentially fatal medical condition that requires immediate emergency medical treatment. It can rapidly progress from the initial stages to the most severe stage, which are severe sepsis and septic shock. 

Most symptoms of sepsis are similar to those of infections. However, sepsis symptoms can worsen rapidly. Some of the most common symptoms of sepsis that indicate a severe problem include a high fever, fast heart rate, rapid breathing, swelling, and pain. Other signs and symptoms of severe sepsis include low blood pressure, cold or clammy skin, diarrhea, dizziness, and confusion or altered mental status.

Symptoms can progress into severe pain, low urine output, and unconsciousness. If you notice any early signs of sepsis in yourself or someone else, seek immediate medical care.

RELATED: Sepsis symptoms: what are the early signs of sepsis? 

How is sepsis diagnosed?

Healthcare providers follow a well-defined set of guidelines to make a diagnosis. They will initially take vital signs and rapidly assess the symptoms. If what they’re seeing points to sepsis, they may start administering treatments right away.

Another important step in diagnosis is to determine the source of the infection. CT scans, X-rays, or other medical imaging are often used to find where the infection is. Spinal, joint, and lung fluid cultures may be tested for bacteria or other pathogens causing an infection. Studies show that even when healthcare providers are unable to identify the infecting pathogen, there is no change in the risk of death from sepsis. 

Blood tests can help monitor white blood cell levels and assess kidney or liver function. A healthcare provider may also order constant monitoring of vital signs, such as blood pressure, temperature, and respiratory rate to watch for the progression of the condition. 

Is sepsis hereditary?

Certain genetic factors may influence how likely an individual is to get an infection or have a severe immune response to a pathogen. Because of genetic factors, sepsis does have a strong hereditary component. Adult children of a biological parent who died of infection are five times more likely to get sepsis, making sepsis more hereditary than heart disease or cancer. Exactly how this works is complex. Hundreds of gene variants may contribute to a high sepsis risk. However, other external risk factors, such as chronic health conditions and invasive medical procedures, also play a major role. 

Is sepsis curable?

Sepsis is curable if detected and treated early. The goal of treatment is to treat the underlying infection, support organ functions, and decrease the risk of complications.

People with sepsis are typically treated in an emergency room or intensive care unit (ICU). Initial treatment consists of IV fluids to restore blood volume, antimicrobial drugs to treat the underlying infection, and vasopressors (drugs that tighten blood vessels) to raise blood pressure if IV fluids don’t work. 

In severe cases of sepsis, mechanical ventilation for lung problems may be needed. Corticosteroids may be used to reduce inflammation, blood thinners may be prescribed to prevent blood clots, and blood transfusions may be administered to restore oxygen delivery through the blood. In addition, dialysis may be required for acute kidney disease or kidney failure caused by sepsis. 

Many who survive a sepsis emergency will recover completely or nearly completely, particularly if the case is mild. However, sepsis can be such a severe blow to the body that people who survive sepsis may have a high mortality rate in the first few years following treatment. Additionally, about half of sepsis patients experience ongoing physical or psychological problems for months or years, a medical condition called post-sepsis syndrome (PSS). How quickly and how well people recover from sepsis depends on the extent of organ damage sustained during the crisis.

RELATED: Antibiotics 101: what are they and why do we need them?

How to prevent sepsis

Sepsis is triggered by infections, so the best way to prevent sepsis is to avoid infections and manage risk factors. Some strategies to prevent sepsis include:

• Distance from people who are sick with infectious diseases

• Stay current with recommended vaccinations

• Immediately clean wounds and treat them with antiseptics if possible

• Cover wounds until they heal

• Make hand washing a regular habit

• Bathe and shower regularly

• Take care of chronic conditions by regularly visiting a healthcare professional and taking any prescribed medications

• Monitor infections for signs they’re getting worse, such as a fever lasting more than a few days or a severe headache that accompanies a fever

• Know the signs of sepsis and get immediate medical care if they appear, such as confusion, fast heart rate, and confusion

FAQs about sepsis causes

What bacteria causes sepsis?

Nearly any bacterial infection could worsen into sepsis. The most common types of bacteria that cause infections that lead to sepsis are Staphylococcus aureus, Streptococcus pyogenes, Klebsiella spp., Pseudomonas aeruginosa, and Escherichia coli. The type of infection you have may affect the risk and severity of sepsis that can develop. 

What causes sepsis shock?

Septic shock is the most severe stage of sepsis. It is the final stage in which insufficient blood circulation may result in organ failure. The condition is so dire that the mortality rate is around 40% or higher for people treated in hospitals. If sepsis is left untreated, it could rapidly worsen into severe sepsis, septic shock, and coma or death.

What causes sepsis in the blood?

Sepsis occurs as an inflammatory response to an infection from bacteria that enters the blood. The infection may start in other areas of the body, such as the lungs, respiratory tract, or gastrointestinal tract. However, in some people, especially those with risk factors such as a weakened immune system or recent procedure, bacteria can enter the bloodstream and cause a severe immune response. This can lead to severe inflammation, organ failure, and even death. 

What causes hypotension in sepsis?

Low blood pressure is a common sign of sepsis that shows that blood is not flowing well enough to bring oxygen to the body’s tissues. Sepsis can cause inflammation of the blood vessels, which leads to the widening of the blood vessels (vasodilation). This then causes fluids in the blood to leak out of the blood vessels, lowering blood volume and blood pressure. 

What causes sepsis in older adults?

Older adults have a higher risk of developing sepsis than younger adults. There are several reasons for this. First, older adults are more likely to be hospitalized, undergo surgery, or have catheters or device implants, all of which may increase the risk of sepsis. Older adults are also more likely to have a weaker immune system or chronic conditions that make them more susceptible to severe infections.

What’s next? Additional resources for people with sepsis

Test and diagnostics

• Bacterial sepsis, StatPearls

• Early recognition and management of sepsis in adults: the first six hours, American Family Physician

• Sepsis: diagnosis and management, American Family Physician

Treatments

• How can I get ahead of sepsis?, Centers for Disease Control and Prevention (CDC)

• Sepsis treatments and medications, SingleCare

• Septic shock, StatPearls

Scientific studies and clinical trials

• Genetic variants associated with sepsis, PLOS One

• Neither blood culture positivity nor time to positivity is associated with mortality among patients presenting with severe manifestations of sepsis: the FABLED cohort study, Open Forum Infectious Diseases

• Prevalence, underlying causes, and preventability of sepsis-associated mortality in US acute care hospitals, JAMA

• Sepsis, severe sepsis and septic shock: changes in incidence, pathogens and outcomes, Expert Review of Anti-Infective Therapy

More information on related health conditions

• Pneumonia treatments and medications, SingleCare

• Post-sepsis syndrome, Sepsis Alliance