Blood Culture Collection Strategies for Suspected Bloodstream Infection (SIMPLE-BC)
Diagnostic Performance of Single-Venipuncture and Sequential Two-Venipuncture Blood Culture Collection Strategies in Adults With Suspected Bloodstream Infection: A Prospective Within-Participant Diagnostic Study
Blood cultures are the reference standard for diagnosing bloodstream infections and are essential for the management of patients with suspected sepsis. Their diagnostic performance depends strongly on the total volume of blood collected, while each additional venipuncture may increase patient discomfort, staff workload, and the opportunity for contamination.
This prospective diagnostic study will evaluate two blood culture collection strategies within the same adult participant. Consecutive patients with a clinical indication for blood culture collection will be enrolled at Izola General Hospital. During the initial venipuncture, two complete blood culture sets, consisting of two aerobic and two anaerobic bottles and approximately 40 mL of blood, will be collected. One additional set, consisting of one aerobic and one anaerobic bottle and approximately 20 mL of blood, will then be collected from a second venipuncture site during the same diagnostic episode, generally within 30-60 minutes according to routine clinical workflow.
The diagnostic performance of the single-venipuncture strategy will be determined from the initial four bottles. The diagnostic performance of the sequential two-venipuncture strategy will be determined from all six bottles. Each participant will therefore serve as their own control. The primary outcome is the paired difference in detection of clinically significant bloodstream pathogens. Secondary outcomes include the incremental diagnostic yield of the additional set, contamination, overall positivity, time to positivity, and the distribution of pathogens and contaminants.
The investigators hypothesize that the single-venipuncture strategy will identify most clinically significant bloodstream pathogens detected by the complete protocol, while the additional set will provide a measurable but limited incremental diagnostic yield.
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Bloodstream infections are associated with substantial morbidity and mortality, particularly in patients with sepsis and septic shock. Timely identification of the causative microorganism enables targeted antimicrobial treatment and supports antimicrobial stewardship. Blood cultures remain the microbiological reference standard, but their performance is influenced by pre-analytical factors, particularly the total blood volume collected, the number of culture bottles, timing of collection, and contamination during venipuncture.
Conventional practice commonly involves collection of blood culture sets from two separate venipuncture sites. However, available evidence suggests that total blood volume may contribute more to pathogen detection than the number of venipunctures. Collecting multiple bottles during one venipuncture may simplify the procedure and improve compliance with the intended blood volume, whereas each additional venipuncture creates another opportunity for contamination. Prospective within-participant evidence from routine clinical settings remains limited.
This is a single-center, prospective, within-participant diagnostic study conducted at Izola General Hospital. Consecutive adults for whom the treating physician orders blood cultures as part of routine care will be assessed for eligibility. The clinical indication for blood culture collection and all treatment decisions will remain under the responsibility of the treating team.
During the initial venipuncture, two complete blood culture sets will be collected, comprising two aerobic and two anaerobic bottles with a target total blood volume of approximately 40 mL. During the same diagnostic episode, generally within 30-60 minutes and according to routine clinical workflow, an additional blood culture set comprising one aerobic and one anaerobic bottle with approximately 20 mL of blood will be collected from a different venipuncture site. The complete study collection will therefore consist of six bottles and approximately 60 mL of blood.
The initial four bottles will define the single-venipuncture strategy. All six bottles will define the sequential two-venipuncture strategy. Because both diagnostic strategies are reconstructed from specimens obtained from the same participant, participant-level clinical characteristics are held constant and each participant serves as their own control. The comparison evaluates the incremental contribution of the additional set and cannot separate the effect of the second venipuncture from the effect of the additional 20 mL of blood.
All bottles will be transported, incubated for five days, and processed according to routine microbiology laboratory procedures. Positive cultures will undergo microorganism identification and antimicrobial susceptibility testing when clinically indicated. Isolates will be classified as clinically significant pathogens or contaminants using predefined criteria based on organism identity, the pattern of positive bottles and sets, and available clinical information. The primary analysis will compare participant-level pathogen detection between the initial four-bottle strategy and the complete six-bottle strategy using paired methods.
The study is intended to quantify the diagnostic performance of a simplified collection strategy and the incremental value of the additional blood culture set. The results may inform local blood culture collection policy and future diagnostic stewardship recommendations.
Study Type
Enrollment (Estimated)
Phase
- Not Applicable
Contacts and Locations
Study Locations
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Izola, Slovenia
- Izola General Hospital
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Adult
- Older Adult
Accepts Healthy Volunteers
Description
Inclusion Criteria:
- Age 18 years or older.
- Clinical indication for blood culture collection determined by the treating physician as part of routine care.
- Planned collection of peripheral blood cultures during the current diagnostic episode.
- Ability to complete the study collection protocol.
- Informed consent obtained in accordance with the ethics committee approval and institutional requirements.
Exclusion Criteria:
- Inability to obtain blood cultures from two separate peripheral venipuncture sites.
- A clinical condition in which the treating physician considers the additional blood collection inappropriate or unsafe.
- Inability to obtain the intended blood volume because of failed collection or premature discontinuation.
- Blood cultures collected exclusively through an intravascular catheter.
- Declined consent or withdrawal of permission for study participation or use of study data, where applicable.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Diagnostic
- Allocation: N/A
- Interventional Model: Single Group Assignment
- Masking: None (Open Label)
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
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Experimental: Standardized Six-Bottle Blood Culture Collection
All participants undergo an initial single venipuncture yielding four blood culture bottles, followed by an additional two-bottle set collected from a second venipuncture site during the same diagnostic episode, generally within 30-60 minutes.
Diagnostic results from the initial four bottles are compared with results from all six bottles within the same participant.
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Two aerobic and two anaerobic blood culture bottles, targeting approximately 40 mL of blood, are collected during the initial venipuncture.
One additional aerobic and one anaerobic bottle, targeting approximately 20 mL, are collected from a different venipuncture site during the same diagnostic episode, generally within 30-60 minutes.
The complete collection totals six bottles and approximately 60 mL of blood.
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What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
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Paired difference in detection of clinically significant bloodstream pathogens
Time Frame: From initial collection through completion of the five-day blood culture incubation period
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For each participant, detection of at least one clinically significant bloodstream pathogen using the initial four bottles collected during one venipuncture will be compared with detection using all six bottles collected during the complete sequential protocol.
Results will be reported as paired proportions and the absolute paired difference with a 95% confidence interval.
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From initial collection through completion of the five-day blood culture incubation period
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Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
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Incremental diagnostic yield of the additional blood culture set
Time Frame: From initial collection through completion of the five-day blood culture incubation period
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Proportion of participants in whom a clinically significant bloodstream pathogen is detected only in the additional two-bottle set and is not detected in the initial four bottles.
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From initial collection through completion of the five-day blood culture incubation period
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Blood culture contamination
Time Frame: From initial collection through completion of the five-day blood culture incubation period
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Participant-level occurrence of one or more isolates classified as contaminants in the initial four-bottle strategy and in the complete six-bottle strategy, according to predefined microbiological and clinical criteria.
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From initial collection through completion of the five-day blood culture incubation period
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Overall blood culture positivity
Time Frame: From initial collection through completion of the five-day blood culture incubation period
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Participant-level detection of any microorganism, including clinically significant pathogens and contaminants, using the initial four bottles and using all six bottles.
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From initial collection through completion of the five-day blood culture incubation period
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Collaborators and Investigators
Sponsor
Collaborators
Investigators
- Study Director: Mladen Gasparini, Izola General Hospital
Study record dates
Study Major Dates
Study Start (Actual)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
Other Study ID Numbers
- 0120-649/2025-2711-6
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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