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What is sepsis?

Sepsis is the body’s systemic inflammatory response to a bacterial infection. Sepsis is serious, overwhelming, and sometimes life-threatening. An infection may begin in one site of the body and then spread to the blood (bacteremia) and possibly to other sites. For example, a urinary tract infection may spread from the bladder and/or kidneys into the blood and then be carried throughout the body, infecting other organs.

The term septicemia is sometimes used to describe this condition. While the term septicemia refers to the presence of disease-causing organisms like bacteria in the bloodstream, sepsis refers to the body’s overwhelming response to the infection.

Normally, a person’s immune system targets a specific threat such as bacteria and limits its response to the infected area. With sepsis, the body initiates a generalized inflammatory response. This can cause a significant rise or fall in body temperature, increased heart and respiration rates, and a decrease in blood pressure. If not treated successfully, sepsis can progress to severe sepsis.

As the condition progresses to severe sepsis, the amount of oxygen that is carried to tissues and organs decreases, blood clots can form in the capillaries, and fluids can leak from the blood into tissues. This can cause fluid build-up in the lungs and reduce respiratory function. Overall, the body’s acid-base balance becomes disrupted, circulation is impaired, waste products begin to accumulate, tissues are damaged, and organs such as the lungs, kidneys, and liver begin to fail. In the last stage of sepsis, septic shock, there may be multiple organ failure (MOF) and low blood pressure that is resistant to treatment.

Although sepsis occurs in hospitalized patients, most people who develop the reaction do so outside the hospital and may seek care in a hospital emergency room. According to the Centers for Disease Control and Prevention, about 70% of people who develop sepsis outside the hospital have used health services recently or have a chronic condition that requires frequent medical attention. It is more prevalent in newborns and infants and in the elderly. Other people at risk for sepsis include those with trauma (for example, after surgery), those with invasive medical devices such as catheters, those with chronic illnesses, and people with weak immune systems (immunocompromised).

Sepsis is a major health problem. In the U.S., mortality rates due to sepsis range from 25-50%. Comparable figures have been reported for other parts of the world, including Europe and South America.


About Sepsis

Signs and Symptoms

The signs and symptoms associated with sepsis that a person experiences depend upon the organs affected, the severity of the condition, and the person’s general health status. They may be nonspecific and, in the very young and elderly, may not be typical. Other medical conditions may cause similar symptoms. It is important to quickly distinguish between sepsis and other conditions, as they are treated differently.

Signs and symptoms of sepsis may include:

  • Fever, shivering, chills
  • Clammy or sweaty skin
  • Extreme pain or discomfort
  • Rapid breathing
  • Rapid heart rate
  • Confusion or disorientation

Additional signs and symptoms may indicate a progression to severe sepsis as organs begin to fail. These may include:

  • Less frequent urination (kidney dysfunction)
  • Abdominal pain
  • Nausea and vomiting
  • Difficulty breathing, cough
  • Chest pain (abnormal function of the heart)
  • Pelvic or flank pain
  • Mottled skin (skin that is blotchy or spotted with different shades of color)

Signs and symptoms of septic shock may include those listed above plus a severe drop in blood pressure.


Diagnosing sepsis can be difficult. The criteria for diagnosis include high or low body temperature, fast heart rate and respiratory rate, plus a probable or known infection.

There is no single test that can identify sepsis. Healthcare practitioners typically order a combination of tests to help diagnose sepsis, distinguish it from other conditions, detect the inflammation associated with sepsis, and to evaluate and monitor the function of the affected person’s organs, blood oxygenation, and acid-base balance.

Laboratory Tests
Some tests that may be done to detect sepsis and identify an infection include:

  • Procalcitonin – may be used in conjunction with clinical evaluations and other tests to determine the risk that seriously ill patients will develop sepsis, or their risk of progressing to severe sepsis, septic shock and risk of dying. This test can help distinguish sepsis from other conditions that cause similar symptoms and can help guide treatment. The level of procalcitonin in the blood increases rapidly and significantly when a person has sepsis.
  • Gram stains and cultures – these tests are done in conjunction with one another. Cultures grow the bacteria that may be in a sample taken from the site of suspected infection, so they can be precisely identified and their susceptibility to various antibiotics determined. Gram stains are used to detect the presence and identify the general type of bacteria. A Gram stain may be done relatively quickly but is not definitive—it provides only presumptive results.
  • Blood culture – one type of culture used to detect bacteria in the blood and evaluate their susceptibility to antibiotics
  • Urinalysis and urine culture – to identify whether the source of infection is a urinary tract infection
  • Cerebrospinal fluid (CSF) analysis, including a culture – may sometimes be done if it is thought that the person has an infection of the central nervous system (meningitis or encephalitis).
  • Sputum culture – to help diagnose bacterial pneumonia
  • Cultures of other body fluids may be done as needed to detect the source and type of infection.

Some general, non-specific tests that may be done include:

Other tests may also be done as needed to help evaluate health status or to identify or rule out complications or other conditions, such as troponin to detect a heart attack.

Non-Laboratory Tests
These tests may be ordered to evaluate the health of organs, detect complications, and to help locate an infection:

  • ECG – to evaluate heart rhythm or injury
  • X-ray
  • CT (computed tomography) scan
  • MRI (magnetic resonance imaging)
  • Ultrasound

For more on imaging studies, see the web site


Sepsis can have severe clinical consequences (morbidity) and has a high death (mortality) rate. The successful treatment of sepsis depends on an early diagnosis and identification of the specific bacterial cause. This can be complicated by the fact that people with sepsis often present with symptoms that are not specific to sepsis.

It is important to begin treatment early and to monitor the affected person carefully. Treatment may begin in the hospital emergency room (ER) and is frequently continued and monitored with the person in an intensive care unit (ICU).

Treatment is focused on resolving the infection, stabilizing the person’s blood pressure and oxygen supply, restoring acid-base balance, and supporting organ function.

Broad-spectrum antibiotics are usually given intravenously (IV). Drug therapy may be changed to a more targeted therapy once the exact type of bacteria causing the sepsis is identified and antibiotic susceptibility testing is performed.

IV fluids are given to help improve and stabilize blood pressure. Sometimes medications are given to constrict blood vessels and increase blood pressure.

Supplemental oxygen may be necessary, and some people need to be put on a mechanical ventilator to assist with breathing.

Other organ support, such as kidney dialysis, is sometimes necessary when organs start to fail.

Surgical procedures are sometimes necessary to remove medical devices such as catheters that may be the source of the infection, to drain abscesses or fluids, to remove and/or fix damaged tissue, and to remove blockages.

View Sources

Sources Used in Current Review

(Reviewed August 23, 2016) U.S. Centers for Disease Control and Prevention. Sepsis Basic Information and Patient Resources. Available online at Accessed March 2017.

Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016. Critical Care Medicine March 2017, Volume 45, Issue 3, Pp. 486–552. Available online at Accessed March 2017.

(Updated March 18, 2016) Cunha B. Bacterial Sepsis. Medscape Reference. Available online at Accessed March 2017.

(Updated: May 17, 2016) Kalil A. Septic Shock. Medscape Reference. Available online at Accessed March 2017.

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