Bacteremia – Definition
Bacteremia (from bacteria + Latin suffix -emia = blood related) is the presence of the bacteria in the bloodstream (1).
Bacteremia is not the same as septicemia (sepsis), which is bacteremia accompanied with an inflammation in the blood.
Both Gram-positive bacteria, like staphylococci or streptococci, or Gram-negative bacteria, like Bacteroides, may be involved in bacteremia.
Bacteremia – Causes
Bacteria may enter the blood from different sources:
- A minor injury occurring during toothbrushing may push some bacteria from the gums into the bloodstream; bacteria are usually quickly removed from the bloodstream by the immune system, so no symptoms usually develop.
- Infected wound
- Incision of a boil
- Dental procedure, like tooth extraction
- Inserting an intravenous or bladder catheter
- Injecting (street) drugs with an infected needle
- Existing infection anywhere in the body, often from infected lung (pneumonia), urinary tract (UTI), gastrointestinal tract (in severe food poisoning), burns or bedsores (decubitus ulcers)
Bacteremia – Symptoms
Mild bacteremia, when present without inflammation in the blood, caused by regular activity as toothbrushing, usually causes no symptoms; rarely fever appears (1).
If in a person with a known or suspected infection high fever, rapid breathing, rapid heart beat, paleness, nausea, and profound weakness appear in a short period of time (hours), this may speak for progression of bacteriemia to septicemia.
Bacteremia May Result in Infection of Various Organs
When a lot of bacteria enter the blood, they can cause infection of the brain membranes (meningitis), bones (osteomyelitis), heart sac (pericarditis), the lining of the heart valves (endocarditis) or joints (infectious arthritis). Symptoms depend on the affected organ and severity of infection.
Individuals with heart valve disorders, prosthetic joints, chronic diseases or weakened immune system are at increased risk to develop infection during bacteremia. A tooth extraction or incision of a boil can result in endocarditis in a person with a heart valve disorder. During inserting of a catheter into a vein of a patient with AIDS, some skin bacteria can be pushed into the blood, what can result in infection, like meningitis.
Diagnosis and Treatment of Bacteremia
Bacteremia can be confirmed by a blood culture, a laboratory test during which bacteria grow from a sample of your blood and thus become visible.
Individuals at increased risk of developing infection during bacteremia should get antibiotics prior to certain procedures, like tooth extraction or certain surgical procedures (antibiotic prophylaxis).
What Is Septicemia or Blood Poisoning?
A term septicemia may cause a lot of confusion; for some it refers to bacteremia (presence of bacteria in the bloodstream) and for others it refers to sepsis (bacteremia + blood inflammation). Since a term septicemia is still widely used, a reader should be aware of its two possible meanings in different health articles.
Blood Poisoning Is Not An Appropriate Term
To ad to the confusion, a term blood poisoning is often used as a synonym for septicemia (or sepsis). Poisoning can be caused by substances other than those released by microbes, while sepsis is always caused by microbes, so a term blood infection is preferable as an informal name for sepsis.
What Does Septic Mean?
Septic (pronounced septik, from Greek sepein = to rot, putrefy), literally means rotten.
In medicine, a term septic may have different meanings:
- Septic - contaminated by microbes, as opposed to aseptic – microbes free, sterile.
- Septic system, including septic tank, is a system for wastewater and sewage disposal.
- Septic infection is an infection with localized pus collection in particular organ. Examples are septic wound, septic arthritis, septic meningitis, septic pleural effusion, etc.
- Septicemia may, to some, mean bacteremia, and to others sepsis, what may be quite confusing, so finding out exact meaning of septicemia from the context of particular health text is important.
- Sepsis or blood infection is a serious health condition, in which microbes invade the blood (usually from existing severe infection, like pneumonia) and trigger high fever, rapid breathing and heartbeat.
- Septic shock is a life threatening condition with a sudden, severe drop in blood pressure during sepsis.
Viremia is the presence of viruses in the bloodstream.
Viremia commonly occurs in viral infections, but is dangerous only in certain infections (see examples below).
Symptoms of Viremia
Viral infections, like influenza, measles, infectious mononucleosis or hemorrhagic fever, spread into the blood and throughout the body and cause “systemic” symptoms, like headache, fever, skin rash, diarrhea, and muscle pains. Exact symptoms depend on a type of infection; there are no “specific symptoms of viremia”.
Primary and Secondary Viremia
Primary viremia is an invasion of viruses into the blood from the initial site of infection. Viruses can then infect various organs, like the lymph nodes or liver, and spread into the blood again after some days or weeks; this is secondary viremia.
Diagnosis of Viremia
Viremia can be confirmed by detecting viral RNA by polymerase chain reaction (PCR).
Viremia in CMV and Hepatitis C
Citomegalovirus (CMV) viremia increases the risk of death in HIV positive patients (1). CMV viremia can be sometimes succesfully treated with ganciclovir (2).
In infection with hepatitis C virus (HCV), viremia persisting for 1 year represents failure of treatment (3). Hepatitis C viremia may be associated with increased risk of diabetes II (4).
Other Important Examples of Viremia
Secondary viremia in rabies, when a vaccine is no longer effective, regularly resulting in death.
Herpes virus (HSV) viremia after rough scratching of a labial herpes (cold sore) may result in herpetic encephalitis.
Chronic rubella viremia after rubella vaccine may result in chronic arthritis (5).
Treatment of Viremia
Viremia can be sometimes treated with anti-viral drugs, like ganciclovir, ribavarin and others.
What Is Fungemia?
Fungemia is the presence of fungi in the bloodstream. Fungemia caused by a yeast Candida is called candidemia. Fungemia can cause life threatening infections of internal organs, like heart valves or brain, so it is important to recognize it and treat it promptly.
Symptoms and Causes of Fungemia
Fungemia should be suspected in a patient with extensive skin burns, lowered immune system (like in AIDS or cancer, including leukemia) or after abdominal surgery, receiving broad-spectrum antibiotics, and having fever, brain fog, itchy skin, non-healing wounds or unusual discharge. Sometimes symptoms may appear weeks or months after invasion of fungi into the blood.
Antibiotics kill bacteria normally present on the skin and in the gut, providing more space for fungi (which are also normally present there in a limited amount), which therefore overgrow. These fungi can invade into the blood through intravenous catheters or from the intestine. Main fungi involved are Candida albicans, Candida glabrata and Aspergillus (1). Fungemia in a person with normal immune system and not receiving antibiotics is not likely (1).
Diagnosis of Fungemia
Fungemia is confirmed by blood culture, but this is often false negative, so it should be repeated if fungemia is still suspected. Blood tests regularly show decreased level of neutrophil leukocytes (a type of white blood cells) – this is called neutropenia.
Treatment of Fungemia
Fungemia should be treated with anti-fungal drugs according to blood culture results.
Article reviewed by Dr. Greg. Last updated on September 10, 2012