Last Review Date: December 30, 2018

What is sepsis?

Sepsis is the name given to a systemic (widespread) inflammatory response caused by infection, most commonly by bacteria but may also be virus, fungi or protozoa. The infection may begin in one site of the body and then spread to the blood and possibly to other sites. While the term bacteraemia or fungaemia refers to the presence of bacteria or fungi in the bloodstream, sepsis, refers to the response of the body to the infection in the bloodstream. The term septicaemia was historically used to describe sepsis with evidence of bacteraemia, but it is no longer consider to accurately describe the process involved.

Sepsis is a serious condition that can progress from sepsis to severe sepsis and then to septic shock with the failure of one or more organs (multiorgan failure, MOF). Successful treatment often requires intensive care unit (ICU) support. Although sepsis commonly occurs and is identified in hospitalised patients, it can also develop in non-hospitalised patients who may then present to the hospital accident and emergency department. It is more prevalent in newborns and infants and in the elderly. Patients at risk for sepsis include those with chronic or severe illness, who are immunocompromised, have invasive medical devices such as catheters, or trauma (including after serious surgery).

Sepsis is a major health problem. Septicaemia may be fatal in up one in four cases in Australia. Comparable figures have been reported for other parts of the world, including Europe and South America.

Normally a person's immune system targets specific threats and limits the response to the area that is infected. Healthy people can have a temporary bacteraemia after brushing their teeth, as a result of harmless mouth bacteria entering the bloodstream through tiny splits in the gums. These bacteria almost never cause infection and healthy people clear them easily from the bloodstream. With sepsis, a generalised inflammatory response is initiated by the body. This can cause a significant rise or fall in body temperature (fever), increased heart (tachycardia) and respiration (tachypnoea) rates, and a decrease in blood pressure (hypotension). If not treated successfully, as noted above, sepsis can progress to severe sepsis and then to septic shock. 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 leakage can cause fluid build-up in the lungs, thereby reducing 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. With the last stage of sepsis, septic shock, there may be multiple organ failure and low blood pressure that is resistant to treatment.

Signs and Symptoms

The symptoms 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 these conditions as they are treated differently.

Symptoms of sepsis may include:

  • Fever (increased temperature) or coolness (decreased temperature)
  • Chills
  • Rigors- uncontrolled shaking
  • Rapid breathing
  • Rapid heart rate
  • Fatigue
  • Headache

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

  • Confusion, mental changes
  • Anxiety
  • Decreased urine output (kidney dysfunction)
  • Abdominal pain
  • Nausea and vomiting
  • Difficulty breathing, cough
  • Chest pain (abnormal function of the heart)
  • Pelvic or flank pain
  • Mottled skin

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


Testing is ordered to help diagnose sepsis, distinguish it from other conditions, and to evaluate and monitor the function of the affected person's organs, blood oxygenation, and acid-base balance.

Laboratory Tests

Testing may include:

In addition to the tests listed above, a cerebrospinal fluid (CSF) examination may sometimes be ordered if it is thought that the person has meningitis.

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

Non-Laboratory Tests

May be ordered to evaluate organ status, detect complications, and to detect location of 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 Inside Radiology.


Sepsis can have severe clinical consequences (morbidity) and has a high mortality rate. The successful treatment of sepsis depends on an early diagnosis and identification of the specific bacterial cause. The problem is that patients with sepsis often present, as noted in the previous section, with symptoms that are not specific to sepsis. It is important to begin treatment early and to monitor the person with sepsis carefully. Treatment may begin in the hospital accident and emergency department ( A&E) and is frequently continued and monitored with the person in an intensive care unit (ICU). Treatment is focused on addressing the infection, stabilizing the person's blood pressure and oxygen supply, restoring acid-base balance, and supporting their organ function.

Broad-spectrum antimicrobials are usually given intravenously (IV). Drug therapy may be changed to a more targeted therapy once the microorganism causing the sepsis is identified.

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 require mechanical ventilation 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.

Related Pages

On This Site
Tests: Blood GasesBlood CultureUrine CultureProcalcitoninFull Blood CountLactateCerebrospinal fluid examinationProthrombin time (PT), Activated partial throboblastin time (APTT)
Conditions: AcidosisUTIWound and Skin Infections

Elsewhere On The Web
Sepsis Alliance: Video Library
Journal of the American Medical Association: Sepsis

Better Health Channel: Septicaemia (AUS)