Questions and Answers
What is the recommended volume of blood culture to collect from adults suspected of bacterial endocarditis?
How should cerebrospinal fluid (CSF) be transported if processed within 48 hours?
What is the ideal method for urine sample collection to reduce contamination?
What should be done to prevent hemolysis of unseparated blood samples?
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In what situation can catheter drawn blood cultures be particularly misleading?
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When should urine samples ideally be sent to the laboratory after collection?
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What is the recommended action to secure the puncture site after a lumbar puncture?
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What temperature should serum samples be kept at if they are to be transported and processed within 10 days?
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What is the first step in the specimen collection process?
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Which of the following is NOT a type of sample commonly collected for microbiological analysis?
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Which principle is essential for the successful collection of a specimen?
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What must be done to blood specimens if they cannot reach the laboratory within 24 hours?
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What is a crucial pre-analytical variable that ensures the integrity of the sample collection process?
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Why is it important to collect microbiology test samples prior to administering antibiotics?
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What is proper labeling critical for during specimen collection?
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Which precaution should be taken during specimen collection to ensure safety?
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What should females do before collecting a midstream urine sample?
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When collecting a urine sample from a catheterized patient, what is the first step?
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What is the correct procedure for males collecting their midstream urine sample?
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Why is it important to discard a few ml of urine before collecting a middle stream sample?
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What must be specified when labeling a urine sample collected from a catheterized patient?
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What materials are necessary for collecting urine from catheterized patients?
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What is the preferred method for stimulating urine flow in young infants?
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What should be avoided when collecting stool samples?
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When storing a stool sample for molecular detection methods, what is the correct temperature?
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Why might rectal swabs be advantageous for collecting stool samples in some patients?
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What is the minimum required volume of sputum to collect for testing?
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What type of transport medium is used for bacterial respiratory specimens?
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What should be done to minimize overgrowth by oral flora during specimen transport?
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What is the disadvantage of collecting a rectal swab for a stool sample?
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Study Notes
Specimen Collection in Microbiology
- Specimen collection involves obtaining tissue or fluids for laboratory analysis to identify pathogenic organisms.
- Essential to perform three main steps: re-analytical (pre-laboratory), analytic (in-laboratory), and post-analytic (post-result).
- Various types of samples include blood, serum, cerebrospinal fluid (CSF), urine, stool, sputum, swabs, aspirates, vomit, and tissue samples.
Pre-Analytical Variables
- Proper patient instructions, preparation, and timely transportation are critical.
- Aseptic sample collection and appropriate storage conditions are vital to prevent contamination.
Principles of Successful Specimen Collection
- Collect specimens at optimal times to enhance pathogen recovery.
- Ensure a sufficient quantity with proper labeling for identification.
- Maintain biosafety and implement decontamination protocols.
- Collect samples before the administration of antibiotics to ensure accurate results.
- Minimize contamination by collecting specimens close to the infection site.
- Utilize correct packaging and ensure rapid transportation to the laboratory.
Blood Specimen Collection
- Venous blood collected directly into blood culture bottles using aseptic techniques.
- Require different volumes based on age: infants (0.5-2 ml), children (2-5 ml), adults (5-10 ml).
- For suspected bacterial endocarditis, collect three sets of blood culture.
Serum Sample Handling
- Transport between 4-8°C for short durations; for long-term storage, freeze at -20°C.
- Avoid repeated freeze-thaw cycles to maintain integrity of immunoglobulins.
Cerebrospinal Fluid (CSF) Collection
- Collected via lumbar puncture under sterile conditions, usually in three labeled containers for microbiology, hematology, and biochemistry.
- Transport at 25-37°C or ambient temperature for bacteria; refrigerate at 4-8°C for viruses if within 48 hours.
Urine Sample Collection
- Use mid-stream clean catch technique, ideal for avoiding normal flora contamination.
- Collect > 1 ml in a sterile, leak-proof container.
- Send samples to the lab within 30 minutes; if delayed, refrigerate for up to 24 hours.
Stool Sample Collection
- Freshly passed stool samples are preferred; avoid bedpan specimens.
- Store at 4°C to preserve samples; do not freeze except for specific tests (e.g., PCR).
Sputum Sample Collection
- Instruct patients to cough deeply and collect sputum in a sterile container, avoiding saliva.
- Minimum sputum volume of 2 ml is required for accurate analysis.
Respiratory Sample Handling
- Transport respiratory specimens other than sputum in specific media (Amie's or Stuart's for bacteria; viral transport medium for viruses).
- Timely transport is crucial to minimize overgrowth by oral flora.
Special Considerations
- For catheterized patients, collect urine aseptically and indicate duration of catheter and antimicrobials if applicable.
- Employ non-invasive methods for urine collection in pediatric patients; perform suprapubic aspiration if necessary.
- Rectal swabs are convenient for certain cases but have limitations in assessing macroscopics and are not recommended for viral analyses.
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Description
This quiz covers the essential principles and practices related to specimen collection in microbiology. Learn about various sample types, pre-analytical variables, and successful collection techniques that are vital for accurate laboratory analysis. Understanding these processes is crucial for effective identification of pathogenic organisms.
