Types and Causes of Bloodstream Infections
- Bacteremias: caused by bacteria, can be asymptomatic or progress to septicemia.
- Viremias: caused by viruses, enter the bloodstream and have access to the rest of the body.
- Fungemias: caused by fungi or yeasts, most commonly Candida species.
- Protozoemia: caused by protozoa, contracted through insect vectors or contact with infected substances.
- Different types of bloodstream infections have specific causative microbes and clinical presentations.
- Bacteria can enter the bloodstream through various routes and sources.
- Gram-positive bacteremia: Staphylococcus, Streptococcus, and Enterococcus species are common causes.
- Staphylococcus aureus is the most common cause of healthcare-associated bacteremia.
- Streptococcal species can cause bacteremia from skin infections, neonatal infections, and oral activities.
- Enterococci commonly live in the gastrointestinal and female genital tracts, leading to healthcare-associated bacteremia.
- Gram-negative bacteria account for a significant percentage of healthcare-associated and community-acquired bacteremia cases.
- Infections in the respiratory, genitourinary, gastrointestinal, or hepatobiliary systems can lead to gram-negative bacteremia.
- E.coli is the most common cause of community-acquired bacteremia, often resulting from urinary tract infections.
- Other organisms causing community-acquired bacteremia include Pseudomonas aeruginosa, Klebsiella pneumoniae, and Proteus mirabilis.
- Salmonella infection is a common cause of bacteremia in Africa.
- Catheter-associated infections are a common cause of bacteremia in healthcare settings.
Mechanism, Diagnosis, and Definition of Bloodstream Infections
- Bacteremia can cause infection in distant sites in the body through hematogenous spread.
- Hematogenous spread is responsible for infections such as endocarditis, meningitis, Potts disease, and osteomyelitis.
- Prosthetic cardiac implants are especially vulnerable to infection from bacteremia.
- Occult bacteremia was a concern in febrile children before widespread use of vaccines.
- Bacteremia is commonly diagnosed through blood culture, where a sample of blood is incubated to promote bacterial growth.
- Bacteria present in the bloodstream can be detected through blood culture.
- Proper sterile process is crucial to prevent contamination of blood samples.
- Certain bacteria in blood cultures, such as Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli, usually indicate true bacteremia.
- Repeat blood cultures may be done to confirm persistent bacteremia.
- Bacteremia is the presence of live bacteria in the bloodstream.
- It can be primary (direct introduction of bacteria into the bloodstream) or secondary (bacteria spreading from another site in the body).
- Transient bacteremia is harmless and lasts for a short time.
- Intermittent bacteremia occurs when bacteria periodically enter the bloodstream from an existing infection.
- Persistent bacteremia is continuous and can be caused by infected heart valves, central line-associated bloodstream infections, or other conditions.
Treatment and Prevention of Bloodstream Infections
- Bacteremia is treated with antibiotics.
- Antibiotic prophylaxis can be given in high-risk situations to prevent bacteremia.
- Prompt and appropriate treatment is essential to prevent complications and reduce mortality rates.
- In healthcare settings, infection control measures play a crucial role in preventing bloodstream infections.
- Proper hygiene and care of invasive devices, such as catheters, can help reduce the risk of bacteremia.
- Bacteremia almost always requires treatment with antibiotics to prevent progression to sepsis.
- Empiric antibiotic coverage should be initiated based on the likely source of infection.
- Antibiotic choice depends on the characteristic organisms causing the infection and patient factors.
- Antibiotic treatment should be narrowed once the specific bacteria causing the bacteremia is identified.
- Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is treated with intravenous vancomycin.
- Uncomplicated MRSA bacteremia is treated with a 14-day course of intravenous vancomycin.
- Treatment choice for streptococcal and enterococcal infections varies by species and antibiotic resistance patterns.
- Treatment of gram-negative bacteremia depends on the causative organism and the patient's exposure to healthcare facilities.
- Recent exposure to healthcare settings may require antibiotics with coverage for pseudomonas aeruginosa or resistant organisms.
- Ceftriaxone and piperacillin-tazobactam are commonly used antibiotics for gram-negative bacteremia.
- Catheter-associated infections are a common cause of bacteremia in healthcare settings.
- Proper catheter care and infection prevention measures can reduce the risk of catheter-associated bacteremia.
- Antibiotic treatment for catheter-associated bacteremia should be guided by the likely source of infection and patient history.
- Pseudomonas aeruginosa coverage may be necessary for healthcare-associated bacteremia.
- Extended generation cephalosporins and beta-lactam/beta-lactamase inhibitor antibiotics are commonly used for gram-negative bacteremia.
Antibiotic Prophylaxis for Bloodstream Infections
- Antibiotic prophylaxis is used to prevent bloodstream infections.
- It is administered before certain medical procedures.
- It reduces the risk of infection in high-risk patients.
- Commonly used antibiotics include penicillin and cephalosporins.
- Prophylaxis guidelines vary depending on the procedure and patient factors.
- Dental antibiotic prophylaxis is given to patients with certain heart conditions before dental procedures.
- It is aimed at preventing infective endocarditis.
- Antibiotics commonly used include amoxicillin and clindamycin.
- Guidelines recommend prophylaxis for high-risk patients.
- Controversy exists regarding the effectiveness and necessity of dental antibiotic prophylaxis.
Other Types of Bloodstream Infections
- Fungemia refers to the presence of fungi in the bloodstream.
- It can be caused by various fungal species,
Bloodstream infections (BSIs) are infections of blood caused by blood-borne pathogens. Blood is normally a sterile environment, so the detection of microbes in the blood (most commonly accomplished by blood cultures) is always abnormal. A bloodstream infection is different from sepsis, which is characterised by severe inflammatory or immune responses of the host organism to pathogens.
| Bloodstream infections | |
|---|---|
| Other names | Blood infection, toxemia, bacteremia, septicemia |
| Specialty | Infectious diseases  |
Bacteria can enter the bloodstream as a severe complication of infections (like pneumonia or meningitis), during surgery (especially when involving mucous membranes such as the gastrointestinal tract), or due to catheters and other foreign bodies entering the arteries or veins (including during intravenous drug abuse). Transient bacteremia can result after dental procedures or brushing of teeth.
Bacteremia can have several important health consequences. Immune responses to the bacteria can cause sepsis and septic shock, which have high mortality rates. Bacteria can also spread via the blood to other parts of the body (which is called hematogenous spread), causing infections away from the original site of infection, such as endocarditis or osteomyelitis.[citation needed] Treatment for bacteremia is with antibiotics, and prevention with antibiotic prophylaxis can be given in high risk situations.
