CAP Pro Course - Microbiology - Blood Cultures (2025 & 2026)

Author: Amber E. Cochran, PhD (ABD), MPH, MLS(ASCP)
Reviewer: Laurie Bjerklie, MA, MLS(ASCP)CM

Continuing Education Credits

Objectives

  • Describe the reasons for drawing a blood culture, including proper collection methods to maximize yield and minimize contamination.
  • Identify factors that optimize recovery of pathogens, including the proper interval between draws, amount of blood necessary per draw, appropriate number of blood cultures, and appropriate media to inoculate/number of bottles to include.
  • Identify the source and incidence of the most frequently isolated pathogens in bacteremia, septicemia, endocarditis, and catheter-related infections.
  • Define methods of identification for positive blood cultures and report results appropriately.
  • Provide methods for determination of clinical relevance of isolates identified in positive blood culture bottle and rule out contaminants.
  • Demonstrate special methods that are necessary to isolate fastidious microorganisms.

Course Outline

  • Describe the reasons for drawing a blood culture, including proper collection methods to maximize yield and minimize contamination.
      • Types of Bloodstream Infections
      • Reasons for Requesting Blood Culture Collection
      • Collection of Blood by Venipuncture
      • Blood Culture Collection Methods that Maximize Yield and Minimize Contamination
      • A nurse contacts the laboratory to inquire about drawing a blood culture on a patient with suspected endocarditis. She wants to know the most appropri...
      • All of the following symptoms may indicate that a patient is suffering from septicemia, except?
  • Identify factors that optimize recovery of pathogens, including the proper interval between draws, amount of blood necessary per draw, appropriate number of blood cultures, and appropriate media to inoculate/number of bottles to include.
      • Timing of Blood Culture Collection
      • Volume of Blood and Number of Cultures Collected
      • Manual Blood Culture Systems: Media, Examination, and Timeline
      • Automated Blood Culture Systems: Benefits and Examination
      • Automated Blood Culture Systems: Timeline and Media
      • Subculture of Positive Blood Cultures
      • A nurse contacts the microbiology laboratory to inquire about blood culture collection. The patient has just received antimicrobial therapy for a loca...
      • Your laboratory uses a manual blood culture system. All aerobic blood culture bottles will be subcultured onto a chocolate agar (CHOC) plate and exami...
      • How many sets of blood cultures (two bottles each) should be drawn for the optimal recovery of organisms responsible for a case of bacterial endocardi...
  • Identify the source and incidence of the most frequently isolated pathogens in bacteremia, septicemia, endocarditis, and catheter-related infections.
      • Most Commonly Isolated Pathogens: Bacteremia/Septicemia
      • Most Commonly Isolated Pathogens: Endocarditis
      • Most Commonly Isolated Pathogens: Catheter-Related Bacteremia/Septicemia
      • Which of the following pathogens is among the most likely causes of bacterial endocarditis that has occurred in a person who is an intravenous (IV) dr...
      • Which of the following etiological agents is often associated with septicemia in infants?
      • A physician calls to ask how commonly E. coli is isolated from blood cultures. What should you tell the clinician?
  • Define methods of identification for positive blood cultures and report results appropriately.
      • Conventional Methods for the Identification of Blood Cultures Positive for Gram-Positive Organisms
      • Conventional Methods for the Identification of Blood Cultures Positive for Gram-Negative Organisms
      • Rapid Methods for the Identification of Positive Blood Cultures
      • Performing Antimicrobial Susceptibility Testing
      • Providing Preliminary Blood Culture Results
      • Providing Interim Blood Culture Results
      • Final Reporting of Positive Blood Cultures
      • Critical Value Reporting
      • A Gram stain from a positive blood culture in an adult patient with suspected bacteremia reveals gram-positive cocci, which are primarily lancet-shape...
      • You are working up a gram-positive bacillus that is growing aerobically in a positive blood culture. The organism is filamentous and has a beaded look...
      • Laboratory policy states that negative blood cultures are incubated for five days before issuing a final report. After five days, which final report i...
      • A 2-year-old child is hospitalized with pneumonia, and two sets of blood cultures are collected to rule out sepsis. A single aerobic bottle is submitt...
  • Provide methods for determination of clinical relevance of isolates identified in positive blood culture bottle and rule out contaminants.
      • Contamination
      • Common Skin Flora Contaminants
      • Monitoring the Contamination Rate
      • Calculating the Contamination Rate
      • When performing the monthly review of organisms isolated and reported from positive blood cultures, you notice a pattern. This pattern includes:The sa...
      • While performing routine rapid identification on a positive blood culture isolate, testing reveals that the isolate is a coagulase-negative staphyloco...
      • It is important to regularly calculate and monitor the blood culture contamination rate, which requires determining if organisms known to be common sk...
  • Demonstrate special methods that are necessary to isolate fastidious microorganisms.
      • Commonly Requested Blood Cultures for Fastidious Bacteria and Media Needed for Recovery
      • Commonly Requested Blood Cultures for Fungi, Mycobacterium, and Viruses
      • There are several methods that can be used to assess the presence of viruses that infect the bloodstream. Which of the following methods is not used t...
      • Abiotrophia (formerly known as nutritionally variant streptococci) will grow in blood culture bottles because of which vitamin present in the patient&...
      • A local farm worker presents to the hospital with a fever and has blood cultures drawn. The blood cultures display growth on the fifth day of incubati...
  • References
      • References

Additional Information

Level of Instruction: Intermediate
Intended Audience: This program is designed as an educational and training tool for medical laboratory scientists, medical laboratory technicians, laboratory supervisors, and laboratory managers. This course is also appropriate for MLS and MLT students and pathology residents.
Author Information: Amber E. Cochran, PhD(ABD), MPH, MLS(ASCP), received a Master's in Public Health from Walden University and a Bachelor's in Medical Technology from Georgia Reagents University in Augusta, Georgia. She is working on her dissertation to receive her PhD in Public Health. She was previously the Clinical Laboratory Manager in the Bacteriology Unit at the Georgia Public Health Laboratory in Decatur, Georgia, and is currently the Molecular Microbiology Supervisor for the Florida Womancare Laboratory in Tampa, Florida.
Reviewer Information: Laurie Bjerklie, MA, MLS(ASCP)CM, is currently an Education Developer. She earned a B.S. in Medical Laboratory Science from the University of North Dakota and an M.A. in Curriculum and Instruction from Saint Xavier University. She has over 15 years of experience in higher education and has held program director and faculty positions in both MLT and MLS programs

This course is part of the CAP Competency Assessment Hub.

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