Sepsis is the body's response to infection — an inflammatory process marked by an elevated heart rate, rapid breathing and abnormal temperature. Even a minor infection, such as strep throat or influenza, can trigger sepsis. It's usually not life-threatening. But complications of sepsis can cause serious illness and death.
Severe sepsis occurs when your natural immune response to an infection goes into overdrive, triggering widespread inflammation and blood clotting in tiny vessels throughout your body. One or more organs may stop working properly or fail. Sepsis can lead to a dangerous drop in blood pressure (septic shock).
About 750,000 people in the United States get severe sepsis each year, and more than 200,000 people die of it. Those at increased risk include older adults, hospital and surgery patients, and people with impaired immune systems. Neonatal sepsis affects a small percentage of newborns, particularly low-birth-weight and premature infants.
Most commonly, bacterial infections lead to sepsis, but it may result from any type of infection — bacterial, viral, parasitic or fungal. Although sepsis often can't be prevented, getting prompt medical care for infections can reduce your risk.
Symptoms
Sepsis develops in response to an infection somewhere in your body. Common infection sites include the lungs (pneumonia), kidneys, skin, abdomen, bowel and pelvis. If you're in the hospital or have had surgery, bacteria may enter your body through openings for tubes used to drain or give fluids (catheters and intravenous lines), surgical wounds or bedsores. Sometimes the source of the infection is unknown.
Sepsis can develop quickly. Signs and symptoms include:
* Fever or low body temperature (hypothermia)
* Fast heart rate
* Rapid breathing
Signs and symptoms indicating that sepsis has progressed to severe sepsis or septic shock include:
* Change in mental status, such as confusion or decreased alertness
* Diarrhea
* Low blood pressure — dizziness when you stand up
* Warm, flushed skin or skin rash or bleeding
* Decreased urine output
Newborns who have difficulty breathing, are unusually sleepy, eat poorly, or have persistently high or low temperatures may have sepsis.
Causes
When bacteria or other germs (infectious organisms) invade your body, your immune system mounts a defense that serves to control the infection and keep it from spreading. Inflammation in the affected area is one part of this defense. Inflammation helps the body repair and heal damaged tissues. Normally, a delicate balance of chemical signals called immune mediators or regulators start — and then stop — the inflammatory process.
In sepsis, however, the process becomes exaggerated. Inflammation extends beyond the infection site and affects the whole body.
Severe sepsis involves a complex cascade of events. The infectious agent and its toxic products provoke the release of too many immune regulators. This triggers widespread inflammation and prompts the formation of microscopic clots in blood vessels throughout the body. At the same time, the overactive inflammatory response interferes with the body's natural ability to break down blood clots.
As a result, even as the heart works harder to pump blood, the clots prevent enough oxygen from reaching body organs and tissues. The out-of-control immune system chemicals may also damage body tissues.
In neonatal sepsis, the newborn may be exposed to bacteria or a virus in the birth canal because of pregnancy complications, such as premature rupture of membranes (water breaking). An infection or bleeding in the mother can also lead to neonatal sepsis. Newborns who require an IV tube or another catheter may develop an infection in the hospital.
Risk factors
Sepsis can occur in anyone with an infection, but you're more likely to develop the condition if you:
* Are over age 65
* Have a bacterial infection in your blood (bacteremia)
* Have a poorly functioning or weakened immune system because of cancer or cancer treatment, diabetes or another chronic disease, or an immune-suppressing disease such as AIDS
* Are taking immune-suppressing drugs
* Have pneumonia
* Are in the hospital
* Have severe injuries, such as bullet wounds or large burns
* Had medical treatment with an invasive device
* Have a genetic tendency for sepsis
Black people are more likely than are white people to get sepsis, and black men face the highest risk.
When to seek medical advice
Most often sepsis occurs in people who are hospitalized. People in the intensive care unit (ICU) are especially vulnerable to developing infections, which can then lead to sepsis.
If you get an infection, or if you develop signs and symptoms of sepsis following surgery, hospitalization or an infection, seek medical care promptly.
Tests and diagnosis
Diagnosing sepsis can be difficult because signs and sympto