Bacteremia, Septicemia - Introduction, Causative Agents, Classification
Introduction of Bacteremia, Septicemia
The presence of viable bacteria in blood as indicated by blood culture is known as bacteremia. The positive blood culture as a result of contamination is called pseudo bacteremia.
Bacteremia in which bacteria have multiplied, produced toxins, and clinical syndromes have gotten severe is known as septicemia. Septicemia occurs when bacteria multiply more rapidly than the immune system is capable of killing and removing microorganisms.
Microbial invasion of the bloodstream resulting from any organism can have serious immediate consequences including shock, multiple organ failure, disseminated intravascular coagulation (DIC), and death.
Causative Agents of Bacteremia, Septicemia
Common etiological agents of bacteremia are:
Staphylococcus aureus
CoNs (Coagulase Negative Staphylococcus)
Enterococcus spp.
Escherichia coli
Pseudomonas aeruginosa
Haemophilus influenzae
Proteus spp.
Bacteroides spp. (anaerobes)
Clostridium spp. (anaerobes)
Klebsiella pneumoniae
Viridans streptococci
Streptococcus pneumoniae
S. agalactiae
S. pyogens
β-hemolytic streptococci
Salmonella spp.
Neisseria meningitidis
Isolation of certain bacterial species from blood can indicate the presence of underlying, occult, or undiagnosed neoplasm.
At neoplasm, the bacteria proliferate and seed the bloodstream. The reduced killing of bacteria by host phagocytes can also cause bacteremia.
Neoplasm
Neoplasm is an abnormal new mass of tissue that serves no purpose. Organisms associated with the neoplasmic disease include:
Clostridium septicum
Streptococcus galldyticus
Aeromonas hydrophila
Plesiomonas shigelloides
Campylobacter spp
Streptococcus anginosis
Classification of Bacteremia, Septicemia
On the basis of the site of margin
Primary bacteremia
They are simultaneous infectious occurrences in blood and other sites of individuals.
Secondary bacteremia
It occurs after primary bacteremia advances. Secondary bacteremia occurs after infection spreads from the primary source to the blood.
Bacteremia of unknown origin
The source of bacteremia is unknown.
On the basis of the causative agent
Gram-positive bacteremia (caused by gram-positive bacteria)
Gram-negative bacteremia (caused by gram-negative bacteria)
Anaerobic bacteremia (caused by anaerobic bacteria)
Polymicrobial bacteremia (caused by multiple bacteria)
On the basis of place on acquisition
Community-acquired
Nosocomial (hospital-aquired)
On the basis of duration
Transient bacteremia
It usually occurs in teething infants or in people who have had dental procedures. Bacteria enter the bloodstream via breaks in gums. It is mostly self-limiting.
Continuous bacteremia
Bacteria are present/released in blood at a constant rate and can cause conditions such as Septic shock, bacterial endocarditis, and endovascular infection.
Intermittent bacteremia
In this case of bacteremia, bacteria are released into the blood approximately 45 minutes before the febrile episode and occur in patients with serious medical conditions.