The bloodstream is normally sterile. Serious infections in various body locations, however, can seed the blood with bacteria, a condition known as bacteremia. Bacteremia may develop as a complication of many types of infections, including pneumonia, meningitis, deep skin infections and urinary tract or intestinal infections. The type of bacteria that causes bacteremia depends on the source of the bloodstream infection. Antibiotics remain the mainstay of treatment for bacteremia.
Pneumococcus
Pneumococcus, also known as Streptococcus pneumoniae, remains the most common cause of bacterial pneumonia in the United States, according to the National Heart, Lung and Blood Institute. Among people with pneumococcal pneumonia, approximately 25 to 30 percent develop an associated bacteremia, reports the Immunization Action Coalition. Approximately one in five people who develop pneumococcal bacteremia die of the infection, adds the IAC. Although pneumococcal disease is a vaccine-preventable illness, the Centers for Disease Control and Prevention reports that roughly 5,000 Americans died of pneumococcal disease in 2009.
Staphylococcus Aureus
Staphylococcus aureus remains a common cause of deep skin infections, abscesses, pneumonia, joint infections and meningitis. Staphylococcal bacteremia may arise in conjunction with these infections. The medical reference text "Principles and Practice of Infectious Diseases" reports that preexisting conditions and risk factors that may contribute to the development of staphylococcal bacteremia include injection drug use, chronic kidney or liver disease, poorly controlled diabetes mellitus, cancer and active skin disease.
Toxic shock syndrome is a potentially life-threatening form of staphylococcal bacteremia caused by strains of Staphylococcus aureus that produce the toxin TSST-1. The toxin circulates in the bloodstream causing a sustained high fever, a bright red skin rash and skin peeling, sore throat, nausea, vomiting, diarrhea, headache, confusion, low blood pressure and muscle pain, reports The Merck Manual for Healthcare Professionals. TSST-1 is referred to as a "superantigen," because of its ability to cause a massive immune system response that can lead to circulatory shock and kidney or liver failure.
Escherichia Coli
The bacterium Escherichia coli, more commonly known as E. coli, remains the leading cause of urinary tract infections in the United States, reports the National Institute of Diabetes and Digestive and Kidney Diseases. E. coli may spread from the urinary tract to the bloodstream, especially among people with infection of the kidneys. Bacteremia that complicates a urinary tract infection, or urosepsis, may lead to shock and kidney failure. Malformations of the urinary system, kidney stones, bladder catheterization, benign prostatic hyperplasia and surgical procedures involving the urinary tract increase the risk for E. coli-related urosepsis.
References
- National Heart, Lung and Blood Institute: Pneumonia, Causes
- Immunization Action Coalition: Pneumococcal Disease, Questions and Answers
- Centers for Disease Control and Prevention: ABCs Report: Streptococcus Pneumoniae, Provisional, 2009
- "Principles and Practice of Infectious Diseases, Sixth Edition"; Gerald L. Mandell, M.D., et al., Editors; 2004
- Merck Manual for Healthcare Professionals: Toxic Shock Syndrome
