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.