Bacteremia

Bacteremia describes the presence of bacteria in the blood. It always suggests a pathology as blood is normally free of bacteria. 
Bacteria can enter the bloodstream in several ways, but the most serious cause is a complication of an infection that affects another part of the body which spreads. It can also be caused by surgery or dental work. In a hospital environment, it can be the result of improper sterilization of a catheter or intravenous line. In drug addicts, it can be caused by a non-sterile hypodermic needle. 
Bacteremia is common in patients with AIDS, diabetes mellitus, patients on dialysis, patients who have received an organ transplant and patients with liver disease.
Bacteremia can lead to sepsis or the spread of an infection throughout the body. 
If bacteremia is detected, antibiotics should be administered immediately. However, in most cases of minor infection, the immune system is capable of removing the bacteria from the bloodstream. 
Bacteremia at Wikipedia