('''Bacteræmia''' in British English) is the presence of
Bacteria in the
Blood . It is the principal means by which local
Infection s spread to distant organs (referred to as ''hematogenous spread''). Bacteremia is typically transient rather than continuous, due to a vigorous
Immune System response when bacteria are detected in the blood.
Bacteremia is most commonly diagnosed by
Blood Culture , in which a sample of blood is allowed to
Incubate with a
Medium that promotes bacterial growth. Since blood is normally sterile, this process does not normally lead to the isolation of bacteria. If, however, bacteria are present in the bloodstream at the time the sample is obtained, the bacteria will multiply in the medium and can thereby be detected. Any bacteria that incidentally find their way to the culture medium will also multiply. For this reason, blood cultures must be drawn with great attention to sterile process. Occasionally, blood cultures will reveal the presence of bacteria that represent contamination from the
Skin through which the culture was obtained. Blood cultures must be repeated at intervals to determine if persistent—rather than transient—bacteremia is present.
Hematogenous dissemination of bacteria is part of the pathophysiology of
Meningitis and
Endocarditis , and of
Pott's Disease and many other forms of
Osteomyelitis . In the hospital, indwelling
Catheter s are a frequent cause of bacteremia and the subsequent
Nosocomial infections, because they provide a means by which bacteria normally found on the skin can enter the bloodstream. Other causes of bacteremia include dental procedures (occasionally including simple tooth brushing), herpes (including herpetic whitlow),
Urinary Tract Infection s, IV drug use, and
Colorectal Cancer . Bacteremia may also be seen in
Oropharyngeal ,
Gastrointestinal or
Genitourinary Surgery or exploration.
A related condition, ''
Septicemia '', refers to the presence of bacteria or their toxins in the bloodstream.
Bacteremia, as noted above, frequently elicits a vigorous immune system response. The constellation of findings related to this response (such as
Fever , chills, or
Hypotension ) is referred to as
Sepsis . In the setting of more severe disturbances of temperature, respiration, heart rate or
White Blood Cell count, the response is characterized as ''
Systemic Inflammatory Response Syndrome '' (''SIRS''). Similar terms are ''sepsis syndrome'', ''
Septic Shock '', and ''
Multiple Organ Dysfunction Syndrome ''.
