Bacteremia (Bacteræmia in British English, also known as blood poisoning or toxemia) is the
presence of bacteria in the blood. Bacteremia is different to
sepsis in that it refers to the presence, not the replication, of pathogens.
Diagnosis
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 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.
Causes
In the hospital, indwelling catheters are a frequent cause of bacteremia and 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 infections, intravenous drug use, and
colorectal cancer. Bacteremia may also be seen in oropharyngeal, gastrointestinal or genitourinary surgery or exploration.
Consequences
Bacteremia is the principal means by which local infections are 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. Hematogenous dissemination
of bacteria is part of the pathophysiology of meningitis and endocarditis, and of Pott's disease and many other forms of
osteomyelitis.
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 sepsis syndrome, septic shock, and may result in
multiple organ dysfunction syndrome.
See also
External links
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