Chapter 30 Bacteremia

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Chapter 30 Bacteremia

• MLAB 2434 Clinical Microbiology
• Cecile Sanders Keri Brophy-Martinez

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Definitions

• Bacteremia presence of bacteria in blood stream
• Some conditions have a period of bacteremia as
  part of the disease process (ex. Meningitis,
  endocarditis)
• Septicemia bacteremia plus clinical signs and
  symptoms of bacterial invasion and toxin
  production

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Definitions (contd)

• Primary Bacteremia blood stream bacterial
  invasion with no preceding or simultaneous site
  of infection with the same microorganism
• Secondary Bacteremia isolation of a
  microorganism from blood as well as other site(s)

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Bacteremic Episodes

• Transient
• Comes and goes
• Usually occurs after a procedural manipulation
  (ex. Dental procedures)
• Intermittent
• Can occur from abscesses at some body site that
  is seeding the blood
• Continuous Bacteremia

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Bacteremia Complications

• Warm shock fever, increased pulse,
  hyperventilation, and warm, dry flushed skin
• Cold shock decreased blood pressure, increased
  pulse, and rapid, shallow respirations
• Septic chock
• Hemodynamic changes, decreased tissue perfusion
  and compromised organ tissue function
• Mortality 40 to 50

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Bacteremia/Septicemia Risk Factors

• Immunocompromised patients
• Increased use of invasive procedures
• Age of patient
• Administration of drug therapy

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Sources of Bacteremia Spread

• Pericarditis and Peritonitis
• Pneumonias
• Pressure sores
• Prosthetic medical devices
• Total hip replacement
• Skeletal system
• Skin and soft tissue

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Clinical Signs and Symptoms

• Abrupt onset of chills, fever, or hypothermia and
  hypotension
• Prostration and diaphoresis
• Tachypnea (rapid breathing) is an early sign of
  bacteremia

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Clinical Signs and Symptoms (contd)

• Laboratory Values in Bacteremia
• Thrombocytopenia
• Leukocytosis or leukopenia
• Acidosis
• Abnormal liver functions
• Coagulopathy
• DIC
• Elevations in CRP, haptoglobin, fibrinogen

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Specimen Collection

• Aseptic collection procedure is critical
  (procedure will be demonstrated in class)
• Amount of blood
• 110 ratio of blood to broth
• Younger than 10 years 1 ml of blood for every
  year of life
• Over 10 years 20 ml

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Specimen Collection (contd)

• Frequency of Collection
• Depends if bacteremia is transient, intermediate
  or continuous
• Number of cultures collected are usually
  inversely related to the type of bacteremia
• Usually x3 from different body sites

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Blood Culture Methods

• Conventional Broth Systems
• One aerobic bottle and one anaerobic bottle per
  blood collection
• Aerobic broth contains soybean casein digest
  broth, tryptic or trypticase soy broth, Brucella
  agar or Columbia broth base
• Anaerobic broth is usually the same as aerobic
  with addition of 0.5 cysteine in an aerobic
  environment
• Must be subcultured and gram stained manually

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Blood Culture Methods (contd)

• Conventional Broth Systems (contd)
• ARD bottle Antibiotic Removal Device used when
  patient is on antibiotics prior to blood
  collection
• Anticoagulants
• SPS
• SAS

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Blood Culture Methods (contd)

• Newer Blood Culture Systems
• Biphasic Broth-Slide System
• Agar paddles attached to top of bottle
• Closed system
• Continuous Monitoring Blood Culture Systems
• BacTec measures 14CO2
• BacTec 9000 Series measures CO2
• ESP measures consumption of gases
• BacT-Alert measures change in pH