Blood Culture Overview

These flashcards cover key concepts and procedures related to blood culture based on the provided lecture notes.

What is a blood culture?

A blood culture is a lab test that inoculates blood taken from a patient into bottles with culture media to determine the presence of infection-causing microorganisms in the bloodstream.

What are the 3 main aims of blood culture?

1. Confirm infectious etiology, 2. Identify the etiological agent, 3. Guide antimicrobial therapy.

When should a blood culture be performed?

Blood cultures should be performed when clinical symptoms suggest a bloodstream infection, such as undetermined fever, shock, severe local infections, abnormal heart rate, and abnormal blood pressure.

What is the recommended blood volume for adult blood cultures?

The recommended volume for an adult is 10 ml per culture bottle, using two sets of bottles.

Why is it important to collect two blood culture sets?

Collecting two sets (four bottles) ensures accurate measurement of bacteria levels and improves detection sensitivity.

What precautions should be taken when collecting a blood sample for a blood culture?

Standard precautions include strict aseptic techniques, collecting from multiple venipuncture sites, and avoiding IV catheters.

What should be included with the blood culture request sent to the laboratory?

Collection site information should be included to help interpret results accurately.

What are common contaminants detected in blood cultures?

Common contaminants include skin flora such as coagulase-negative staphylococci and Corynebacterium species.

What indicates a potential contamination in blood culture results?

Only one positive set among at least two sets drawn at the same time indicates possible contamination.

What are the types of blood culture systems?

1. Manual blood culture: requires daily inspection for growth. 2. Automated blood culture: continuously monitors bacterial growth with sensors.

How many days of incubation are recommended for manual blood culture?

Blood culture is considered negative only if no growth appears after 7 days.

What is Time To Positivity (TTP) in automated blood culture systems?

TTP usually takes 24-48 hours, and can be as early as 8 hours to obtain a positive result.

What is a blood culture?

A blood culture is a lab test that inoculates blood taken from a patient into bottles with culture media to determine the presence of infection-causing microorganisms in the bloodstream.

What are the 3 main aims of blood culture?

1. Confirm infectious etiology, 2. Identify the etiological agent, 3. Guide antimicrobial therapy.

When should a blood culture be performed?

Blood cultures should be performed when clinical symptoms suggest a bloodstream infection, such as undetermined fever, shock, severe local infections, abnormal heart rate, and abnormal blood pressure.

What is the recommended blood volume for adult blood cultures?

The recommended volume for an adult is 10 ml per culture bottle, using two sets of bottles.

Why is it important to collect two blood culture sets?

Collecting two sets (four bottles) ensures accurate measurement of bacteria levels and improves detection sensitivity.

What precautions should be taken when collecting a blood sample for a blood culture?

Standard precautions include strict aseptic techniques, collecting from multiple venipuncture sites, and avoiding IV catheters.

What should be included with the blood culture request sent to the laboratory?

Collection site information should be included to help interpret results accurately.

What are common contaminants detected in blood cultures?

Common contaminants include skin flora such as coagulase-negative staphylococci and Corynebacterium species.

What indicates a potential contamination in blood culture results?

Only one positive set among at least two sets drawn at the same time indicates possible contamination.

What are the types of blood culture systems?

1. Manual blood culture: requires daily inspection for growth. 2. Automated blood culture: continuously monitors bacterial growth with sensors.

How many days of incubation are recommended for manual blood culture?

Blood culture is considered negative only if no growth appears after 7 days.

What is Time To Positivity (TTP) in automated blood culture systems?

TTP usually takes 24-48 hours, and can be as early as 8 hours to obtain a positive result.

Why are strict aseptic techniques crucial during blood culture collection?

Strict aseptic techniques are crucial to prevent contamination of the blood sample with skin flora, which can lead to false positive results and incorrect diagnosis or treatment.

What is the critical initial step performed when an automated blood culture system flags a bottle as positive?

The initial critical step is to perform a Gram stain directly from the positive blood culture bottle to rapidly identify the morphology and Gram reaction of the microorganism, guiding early empirical antibiotic therapy.

What types of culture media are typically found in blood culture bottles?

Blood culture bottles typically contain a rich broth medium (e.g., Tryptic Soy Broth, Brain Heart Infusion) that supports the growth of a wide range of bacteria and fungi, often supplemented with anticoagulants and resins to neutralize antibiotics.