A bloodstream infection is different from sepsis, which is characterized by severe inflammatory or immune responses of the host organism to pathogens.
[5] Bacteremia frequently evokes a response from the immune system called sepsis, which consists of symptoms such as fever, chills, and hypotension.
[8] Severe immune responses to bacteremia may result in septic shock and multiple organ dysfunction syndrome,[8] which are potentially fatal.
[14] Skin ulceration or wounds, respiratory tract infections, and IV drug use are the most important causes of community-acquired staph aureus bacteremia.
Intravenous catheters, urinary tract infections and surgical wounds are all risk factors for developing bacteremia from enterococcal species.
[27] Catheters in the veins, arteries, or urinary tract can all create a way for gram negative bacteria to enter the bloodstream.
[13][28] These include: Bacteremia can travel through the blood stream to distant sites in the body and cause infection (hematogenous spread).
Hematogenous spread of bacteria is part of the pathophysiology of certain infections of the heart (endocarditis), structures around the brain (meningitis), and tuberculosis of the spine (Pott's disease).
The presence of certain bacteria in the blood culture, such as Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli almost never represent a contamination of the sample.
On the other hand, contamination may be more highly suspected if organisms like Staphylococcus epidermidis or Cutibacterium acnes grow in the blood culture.
[citation needed] Two blood cultures drawn from separate sites of the body are often sufficient to diagnose bacteremia.
[34] The patient's skin is typically cleaned with an alcohol-based product prior to drawing blood to prevent contamination.
[34] Prior to drawing blood cultures, a thorough patient history should be taken with particular regard to presence of both fevers and chills, other focal signs of infection such as in the skin or soft tissue, a state of immunosuppression, or any recent invasive procedures.
In transient bacteremia, bacteria are present in the bloodstream for minutes to a few hours before being cleared from the body, and the result is typically harmless in healthy people.
[36] Persistent bacteremia can also occur as part of the infection process of typhoid fever, brucellosis, and bacterial meningitis.
[43] The Infectious Disease Society of America (IDSA) recommends treating uncomplicated methicillin resistant staph aureus (MRSA) bacteremia with a 14-day course of intravenous vancomycin.
Empiric antibiotic therapy should be guided by the most likely source of infection and the patient's past exposure to healthcare facilities.
[45] Extended generation cephalosporins such as ceftriaxone or beta lactam/beta lactamase inhibitor antibiotics such as piperacillin-tazobactam are frequently used for the treatment of gram negative bacteremia.
Short term catheters (in place <14 days) should be removed if bacteremia is caused by any gram negative bacteria, staph aureus, enterococci or mycobacteria.
[46] Long term catheters (>14 days) should be removed if the patient is developing signs or symptoms of sepsis or endocarditis, or if blood cultures remain positive for more than 72 hours.