Impact of Blood Culture Positivity Time on Clinical Management of Pediatric ICU Patients

Study Overview
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Brief Summary
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Sepsis accounts for high morbidity and mortality rates in ICU globally. Early recognition of sepsis with appropriate antimicrobial therapy is critical for the appropriate management of patients (1). Blood culture (BC) is considered the gold standard for sepsis etiological diagnosis , with good sensitivity ,but suffering usually of delay or even failure to detect microorganisms in patients already treated with antimicrobials and failure to identify pathogens other than bacteria or yeast (2, 3). Time-to-positivity (TTP) of blood cultures is defined as the time from the start of incubation to a positive signal. Knowledge of the distribution of blood culture TTP is of clinical benefit in the re-evaluation of patients with a clinical syndrome consistent with infection. A low probability of bacteremia when blood cultures have remained negative after 24 hours (4). Positive episodes with TTP more than or equal 24 h are commonly optimally treated infections, catheter-related infections, or infections caused by slowly growing microorganisms such as Candida or anaerobic Gram-negative bacteria. Growth of multidrug-resistant Gram-negative bacilli is exceptional beyond 24 h. In current clinical practice, bacteremia is considered unlikely if blood cultures have been negative for 48-72 hours (5, 6). Most blood culture bottles turn positive in less than 4 days, shortening the duration of incubation appears the most relevant solution in order to free additional capacity(4). Various disinfectants, such as povidone iodine (PVI), alcohol preparations, and chlorhexidine gluconate ethanol (CHG-ALC), are used for disinfection prior to blood culture sampling. Contamination rates of cultured blood samples vary according to the disinfectant used, sampling site, definition of contamination, and skill level of individuals performing the venipuncture.(7, 8) In this study, Investigators assessed the real life clinical impact on septic ICU patients based on time of blood culture positivity time.

Detailed Description
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Aim(s) of the Research : Evaluate the impact of blood culture positivity time in real -life clinical practice (patient management and reduction of ICU stay, as well as decreases in 30-days mortality.) Investigates the probability of blood culture positivity after 24 hours. evaluate if there was diagnostic value of TTP Identify if there is difference in the blood culture contamination rate between uses of various type of disinfectant. Sample Size Calculation: 120 septic patient in pediatric intensive care unit Study tools: The following will be done to all patients: Data collection: Clinical data (were retrieved from the medical records) : age and weight Date and time of culture collection pre-existing medical conditions (concomitant disease). Clinical parameters at presentation. The most likely source of bacteremia if start empirical antibiotic treatment before collection or not and its type, duration (concomitant antimicrobial therapy) volume of blood drawn in the bottles outcome data. Including change of antibiotic treatment and time to switch to directed therapy, length of ICU stay and 30-day mortality. Microbiological data (were retrieved from the database of the Department of Medical Microbiology.) : date and time of bottle loading ( to know transportation time) date and time in which growth was first reported TTP(time to positivity of blood culture) Pathogen detected by blood culture Blood culture sampling : collecting blood samples as soon as possible after the onset of clinical symptoms, ideally prior the administering antimicrobial therapy. Disinfection using povidone-iodine, alcohol preparation, or chlorhexidine gluconate ethanol (CHG-ALC ), so that each type was used on 40 patients collect 2 sets of blood culture bottles. blood culture was obtained either at one time or over a brief time period (e.g. within 1 hour) from multiple venipuncture sites. Blood for culture must be collected and dispensed aseptically with great care to avoid contaminating the specimen and culture medium Blood culture handling procedures and laboratory techniques: Rapid transportation to microbiology unit. Rapid bottle loading in bioMerieux BacT/Alert Virtuo where it was incubated for 5 days Direct Gram stain was performed for all positive blood culture bottles. Followed by subculture onto solid agar media, including blood agar, chocolate agar & MacConkey agar and sabaroud agar (Diagnostic Media products(DMP). Then identification of microorganisms and antibiotic susceptibility by Vitek 2. Direct reporting method to the pediatric intensive care unit The presence of one of the following microorganisms in a single BC bottle or Blood Culture set was considered as contaminant: coagulase-negative staphylococci (CoNS), with the exception of S. lugdunensis, Propionibacterium spp., Bacillus spp. other than B. anthracis, Corynebacterium spp. (diphtheroids), Aerococcus-like organisms, Micrococcus spp., viridans group streptococci other than S. pneumoniae, and Neisseria spp. other than N. gonorrhoeae or N. meningitidis. These microorganisms were considered as significant when other BC bottles collected 48h before were positive with the same microorganism, after reviewing of clinical data.

Official Title
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Impact of Blood Culture Positivity Time on Clinical Management of Pediatric ICU Patients

Conditions
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Sepsis

Intervention / Treatment
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* Diagnostic Test: direct reporting of time to positivity of blood culture to ICU to know its effect to patients managment


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The population of our study were patients in ICU unit in pediatric hospital of Assuit University Hospitals, that presented with clinical symptoms which may lead to a suspicion of a bloodstream infection or sepsis which is: Undetermined fever ( ≥ 38°C) or hypothermia ( ≤ 36°C). Shock, chills, rigors Severe local infections (meningitis, endocarditis, pneumonia, pyelonephritis, intra-abdominal suppuration etc.) Multiple episodes of bacteremia per patient were allowed if the antimicrobial therapy for the previous episode had been completed and clinical and microbiological cure had been achieved Exclusion Criteria: -blood culture bottles that were drawn in vacation days (because of no distinct control on transportation time, which affect TTP)

Ages Eligible for Study
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Minimum Age: 1 Day
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: direct reporting of time to positivity of blood culture to ICU to know its effect to patients managment|-Disinfection using povidone-iodine, alcohol preparation or chlorhexidine gluconate ethanol (CHG-ALC ), so that each type was used on 40 patients|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Evaluate the impact of blood culture positivity time in patient management and reduction of ICU stay, as well as decreases in 30-days mortality. | investigators measured the time to positivity of blood culture in hours. Then direct reporting the result to the physician ( as few true bloodstream infections were detected after 48 hours) ,,, Then study the impact of the result on therapeutic decisions (start of treatment, or switch or association of antibiotic/antifungal therapy). Then days of hospital stay were measured in the day unit& mortality rate was measured in percentage | through study completion, an average of 1 year. | 
| Investigates the probability of blood culture positivity after 24 hours. | time of positivity of blood culture measured in hours. It was calculated as the time from the start of incubation to a positive signal | through study completion, an average of 1 year. | 
| evaluate if there was diagnostic value of TTP | see if there was a relationship between time of positivity of blood culture (in hour unit) and the type of microorganism,, and And if TTP can distinguish between contaminant and true pathogen | through study completion, an average of 1 year. | 
| Identify if there is difference in the blood culture contamination rate between uses of various type of antiseptic. | Identify if there is a difference in the blood culture contamination rate (measured in percentage) between uses of various types of antiseptic. | through study completion, an average of 1 year. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| - Identify if TTP in real life was superior to expensive modern microbiological techniques for the diagnosis of sepsis | expensive modern microbiological techniques for the diagnosis of sepsis are BioFire FilmArray Blood Culture Identification panel and T2 magnetic Resonance Bacterial Panel | through study completion, an average of 1 year. |