Bacteremia Health Article

Definition

Bacteremia is an invasion of the bloodstream by bacteria.

Description

Bacteremia occurs when bacteria enter the bloodstream. This may occur through a wound or infection, or through a surgical procedure or injection. Bacteremia may cause no symptoms and resolve without treatment, or it may produce fever and other symptoms of infection. In some cases, bacteremia leads to septic shock, a potentially life-threatening condition.

Causes

Several types of bacteria live on the surface of the skin or colonize the moist linings of the urinary tract, lower digestive tract, and other internal surfaces. These bacteria are normally harmless as long as they are kept in check by the body's natural barriers and the immune system. People in good health with strong immune systems rarely develop bacteremia. However, when bacteria are introduced directly into the circulatory system, especially in a person who is ill or undergoing aggressive medical treatment, the immune system may not be able to cope with the invasion, and symptoms of bacteremia may develop. For this reason, bacteremia is most common in people who are already affected by or being treated for some other medical problem. In addition, medical treatment may bring a person in contact with new types of bacteria that are more invasive than those already residing in that person's body, further increasing the likelihood of bacterial infection.

Conditions which increase the chances of developing bacteremia include:

• immune suppression, either due to HIV infection or drug therapy
• antibiotic therapy which changes the balance of bacterial types in the body
• prolonged or severe illness
• alcoholism or other drug abuse
• malnutrition
• diseases or drug therapy that cause ulcers in the intestines, e.g. chemotherapy for cancer

Common immediate causes of bacteremia include:

• drainage of an abscess, including an abscessed tooth.
• urinary tract infection, especially in the presence of a bladder catheter.
• decubitus ulcers (pressure sores).
• intravenous procedures using unsterilized needles, including IV drug use.
• prolonged IV needle placement.
• use of ostomy tubes, including gastrostomy (surgically making a new opening into the stomach), jejunostomy (surgically making an opening from the abdominal wall into the jejunum), and colostomy (surgically creating an articifical opening into the colon).

The bacteria most likely to cause bacteremia include members of the Staphylococcus, Streptococcus, Pseudomonas, Haemophilus, and Esherichia coli (E. coli) genera.