What Are the Causes of Blood Infections?

Blood infections, also known as sepsis, are very serious medical conditions that require prompt treatment. While the main cause of blood infections is an infectious organism in the blood, these organisms can enter the bloodstream in many ways. As a result, there are several causes of blood infections.

Chronic Illnesses

Chronic illnesses make it difficult for the immune system to carry out its purpose of fighting infection. Diabetes, cirrhosis of the liver and HIV/AIDS are examples of chronic illnesses that can reduce the body's defenses against disease. When infections are aggressive and cannot be controlled with antibiotics or antiviral drugs, they can enter the bloodstream and cause sepsis.


Bacterial infections are the most common cause of blood infections. Pneumonia, urinary tract infections, meningitis, cellulitis and appendicitis can all lead to sepsis if they are not properly treated and managed. Viral and fungal infections can also enter the bloodstream and cause a blood infection. Rubella, cytomegalovirus, herpes simplex and the chickenpox virus are all known viral causes of sepsis. Candida is the most common fungal cause of a blood infection.

Severe Injuries or Burns

Someone with severe injuries or burns is at a greater risk for developing a blood infection because bacterial and viral organisms can enter open wounds and get into the bloodstream. Once these organisms are in the blood, they will cause a blood infection if antibiotic therapy is not administered. Severe burns can also inhibit the body's immune response, which makes it easier for existing infections to overwhelm the immune system and enter the bloodstream.

Dirty Needles

IV drug use can cause blood infections when dirty needles are shared among drug users. When a dirty needle is inserted into a vein, bacteria directly introduced into the bloodstream can cause sepsis 1. If a tattoo artist does not disinfect needles between uses, someone who receives a tattoo with one of those dirty needles may develop a blood infection. Piercings that are performed with dirty instruments can also introduce infectious organisms into the blood and cause a blood infection. Anyone considering a tattoo or piercing should choose a reputable professional to avoid the chance of coming into contact with a needle that carries infection.