Skin blotching and inflammation due to sepsis
Blood culture bottles: orange cap for anaerobes, green cap for aerobes, and yellow cap for blood samples from children
Sepsis Steps. Training tool for teaching the progression of sepsis stages
Intravenous fluids being given
Personification of septicemia, carrying a spray can marked "Poison"
Phenotypic strategy switches of microbes capable of provoking sepsis

Life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs.

- Sepsis

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Inflammation of the kidney, typically due to a bacterial infection.

CD68 immunostaining on this photomicrograph shows macrophages and giant cells in a case of xanthogranulomatous pyelonephritis
Diagram showing the typical location of pain
Acute pyelonephritis with increased cortical echogenicity and blurred delineation of the upper pole.
Chronic pyelonephritis with reduced kidney size and focal cortical thinning. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.

Complications may include pus around the kidney, sepsis, or kidney failure.

Bloodstream infections

Bloodstream infections (BSIs), which include bacteremias when the infections are bacterial and fungemias when the infections are fungal, are infections present in the blood.

Micrograph showing a mycosis (aspergillosis). The Aspergillus (which is spaghetti-like) is seen in the center and surrounded by inflammatory cells and necrotic debris. H&E stain.

A bloodstream infection is different from sepsis, which is the host response to bacteria.

Organ dysfunction

Condition where an organ does not perform its expected function.

Many of the internal organs of the human body

Multiple organ failure can be associated with sepsis and is often fatal.


Heart rate that exceeds the normal resting rate.

ECG showing sinus tachycardia with a rate of about 100 beats per minute
12 lead electrocardiogram showing a ventricular tachycardia (VT)

For example, in sepsis >90 bpm is considered tachycardia.


Defined as a body core temperature below 35.0 C in humans.

During Napoleon Bonaparte's retreat from Russia in the winter of 1812, many troops died from hypothermia.
The rate of hypothermia is strongly related to age in the United States
Two American marines participating in an immersion hypothermia exercise
Atrial fibrillation and Osborn J waves in a person with hypothermia. Note what could be mistaken for ST elevation.
The armies of Napoleon retreat from Russia in 1812.
Snow-storm: Hannibal and His Army Crossing the Alps, J. M. W. Turner

Thus, hypothermia risk factors include: substance use disorders (including alcohol use disorder), homelessness, any condition that affects judgment (such as hypoglycemia), the extremes of age, poor clothing, chronic medical conditions (such as hypothyroidism and sepsis), and living in a cold environment.


Defined as having a temperature above the normal range due to an increase in the body's temperature set point.

An analog medical thermometer showing a temperature of 38.7 °C or 101.7 °F
Michael Ancher, "The Sick Girl", 1882, Statens Museum for Kunst
Different fever patterns observed in Plasmodium infections
Hyperthermia: Characterized on the left. Normal body temperature (thermoregulatory set point) is shown in green, while the hyperthermic temperature is shown in red. As can be seen, hyperthermia can be conceptualized as an increase above the thermoregulatory set point.
Hypothermia: Characterized in the center: Normal body temperature is shown in green, while the hypothermic temperature is shown in blue. As can be seen, hypothermia can be conceptualized as a decrease below the thermoregulatory set point.
Fever: Characterized on the right: Normal body temperature is shown in green. It reads "New Normal" because the thermoregulatory set point has risen. This has caused what was the normal body temperature (in blue) to be considered hypothermic.

Intermittent fever, where the temperature elevation is present only for a certain period, later cycling back to normal (e.g., in malaria, leishmaniasis, pyemia, sepsis, or African trypanosomiasis );


Low blood pressure.

Excessive vasodilation can also result from sepsis, acidosis, or medications, such as nitrate preparations, calcium channel blockers, or AT1 receptor antagonists (Angiotensin II acts on AT1 receptors).

Disseminated intravascular coagulation

Condition in which blood clots form throughout the body, blocking small blood vessels.

Micrograph showing acute thrombotic microangiopathy due to DIC in a kidney biopsy. A clot is present in the hilum of the glomerulus (center of image).
The coagulation cascade of secondary hemostasis.
Blood film showing red blood cell fragments (schistocytes)

Relatively common causes include sepsis, surgery, major trauma, cancer, and complications of pregnancy.


Inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.

Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)
Main symptoms of infectious pneumonia
The bacterium Streptococcus pneumoniae, a common cause of pneumonia, imaged by an electron microscope
Cavitating pneumonia due to MRSA as seen on a CT scan
A chest x-ray of a patient with severe viral pneumonia due to SARS
Pneumonia fills the lung's alveoli with fluid, hindering oxygenation. The alveolus on the left is normal, whereas the one on the right is full of fluid from pneumonia.
A chest X-ray showing a very prominent wedge-shaped area of airspace consolidation in the right lung characteristic of acute bacterial lobar pneumonia
CT of the chest demonstrating right-sided pneumonia (left side of the image)
A pleural effusion: as seen on chest X-ray. The A arrow indicates fluid layering in the right chest. The B arrow indicates the width of the right lung. The volume of the lung is reduced because of the collection of fluid around the lung.
Deaths from lower respiratory infections per million persons in 2012
WPA poster, 1936/1937
Pneumonia seen by ultrasound
Right middle lobe pneumonia in a child as seen on plain X-ray

For people with certain variants of the FER gene, the risk of death is reduced in sepsis caused by pneumonia.


Low output of urine specifically more than 80 ml/day but less than 400ml/day.

Sample of human urine

Prerenal: in response to hypoperfusion of the kidney (e.g. as a result of dehydration by poor oral intake, cardiogenic shock, diarrhea, G6PD deficiency, massive bleeding or sepsis)