Clinical and economic impact of contaminated blood cultures within the hospital setting

Validation of the Hospital for Sick Children Algorithm for Discriminating Bacteremia From Contaminants in Children With a Preliminary Positive Blood Culture

STUDY OBJECTIVE

Children with positive blood cultures obtained in the emergency department (ED) prompt urgent actions due to the risk of bacteremia. This study aimed to validate the Hospital for Sick Children algorithm used for discriminating bacteremia from contaminants and identified variables associated with bacteremia in children with positive blood cultures.

METHODS

We conducted a retrospective cohort study of all children with positive blood cultures from a tertiary care, pediatric ED between 2018 and 2022. A 2-step standardized approach defined true bacteremia as the primary outcome based on 1) the bacteria involved and 2) the clinical outcome assessed by 2 reviewers. We evaluated multiple independent variables. We used multiple logistic regression to analyze the association between independent variables and outcome.

RESULTS

Among the 375,428 ED visits, 574 participants were identified, including 286 (49.8%; 95% confidence interval [CI] 45.8% to 53.9%) with bacteremia and 288 (50.2%; 95% CI 46.1% to 54.3%) with contaminants. The algorithm identified 364 children (63.4%) at high risk of bacteremia, 178 (31.0%) at medium risk, and 32 (5.6%) at low risk. The corresponding bacteremia proportions were 62%, 34%, and 0%, respectively, for a sensitivity of 100% and a specificity of 11%. Suspicion of osteoarticular infection (aOR=43.6; 95% CI 16.2 to 118), presence of internal hardware (aOR=24.9; 95% CI 7.2 to 83.5), and presence of Gram-negative bacteria or Gram-positive cocci in chains/pairs (aOR=21.7; 95% CI 11.7 to 40.3) were the most significant predictors of true bacteremia.

CONCLUSION

The Hospital for Sick Children algorithm exhibits 100% sensitivity to detect children with bacteremia but demonstrated low specificity at 11%. We identified predictors to discriminate contaminants from bacteremia.

Economic effects of next-generation sequencing diagnostics in unspecific sepsis patients - a budget impact analysis from the healthcare providers' perspective in Germany

PURPOSE

Next-generation sequencing (NGS) tools have clinical advantages over blood culture but are more expensive. This study assesses the budget impact and break-even point of NGS testing costs from a healthcare provider's perspective in Germany.

METHODS

The budget impact was calculated based on aggregated data of German post-operative surgery cases. Simulated cost savings were calculated based on a simulated reduction in hospital length of stay (LOS) of four or eight days with a positivity rate of 71% and compared to the costs of one (scenario A) or two tests (scenario B) per case. Furthermore, the break-even point of the cost of two tests compared to saved costs through shortened LOS was conducted.

RESULTS

For 9,450 cases, an average budget impact for scenario A and scenario B of €1,290.41 [95% CI €1,119.64 - €1,461.19] and - €208.59 [95% CI - €379.36 - - €37.81] was identified for gastrointestinal and kidney surgery cases, and €1,355.58 [95% CI €1,049.62 - €1,661.55] and €18.72 [95% CI - €324.69 - €287.24] for vascular artery surgery cases, respectively. The break-even analysis showed that using two tests per case could achieve a minimum positive contribution margin with an average of 1.9 tests per case across the study population.

CONCLUSION

The results revealed a positive budget impact for one NGS test and a slightly negative budget impact for two NGS tests per case. Findings suggest that largest cost savings are generated for more severe cases and are highly dependent on the patient population.

Effectiveness of A Nurse-Led Multimodal Intervention in Preventing Blood Culture Contamination: A Before-and-After Study

Blood culture is crucial for accurate and timely bacteremia diagnosis and guide antibiotic therapy. However, during culture sampling, contamination can occur, resulting in misdiagnosis, unnecessary antibiotic exposure, and prolonged hospitalization. This before-and-after intervention study aimed to evaluate the effectiveness of a multimodal intervention in preventing blood culture contamination. The study was conducted in a 170-bed hospital in Portugal and included a total of 23,566 blood cultures. Contamination rates were assessed in two phases: Phase 1 (before intervention, month 0) included 10,928 cultures, and Phase 2 (after intervention, month 6) included 12,638 cultures. During the study period, a multimodal intervention targeting the nursing staff was implemented, consisting of training actions, guideline updates, regular data monitoring and feedback, and introduction of a blood culture pack. Following the intervention, blood culture contamination decreased from 6.8% (Phase 1) to 3.9% (Phase 2). A comparative analysis revealed that the risk of contamination before the intervention was nearly four times higher in first culture, OR = 3.97 (CI 2.86-5.49). Our findings suggest that the multimodal intervention enhanced nurses' adherence to recommended practices, resulting in a reduced risk of blood culture contamination, earlier identification of infectious agents, and improved accuracy of antibiotic therapy.

The next frontier of healthcare-associated infection (HAI) surveillance metrics: Beyond device-associated infections

In recent years, it has become increasingly evident that surveillance metrics for invasive device-associated infections (ie, central-line-associated bloodstream infections, ventilator-associated pneumonias, and catheter-associated urinary tract infections) do not capture all harms; they capture only a subset of healthcare-associated infections (HAIs). Although prevention of device-associated infections remains critical, we need to address the full spectrum of potential harms from device use and non-device-associated infections. These include complications associated with additional devices, such as peripheral venous and arterial catheters, non-device-associated infections such as nonventilator hospital-acquired pneumonia, and noninfectious device complications such as trauma, thrombosis, and acute lung injury. As authors of the device-associated infection sections in the SHEA/IDSA/APIC Compendium of Strategies to Prevent Healthcare-Associated Infections in Acute Care Hospitals, we highlight catheter-associated urinary tract infection as an example of the strengths and limitations of the current emphasis on device-associated infection surveillance, suggest performance metrics that present a more comprehensive picture of patient harm, and provide a high-level overview of similar issues with other infection surveillance measures.

Benchmarking blood culture quality in the emergency department: Contamination, single sets and positivity

OBJECTIVE

To benchmark blood culture (BC) quality in an Australian ED, explore groups at risk of suboptimal BC collection, and identify potential areas for improvement.

METHODS

This retrospective observational study was undertaken to benchmark quality of BCs in a tertiary adult ED in terms of number of BC sets per patient and proportion of patients with false positive (contaminated) BC results.

RESULTS

A single BC set was taken for 55% of patients, with lower acuity patients being more likely to have a single BC set taken. BC false positives occurred in 3.4% of presentations, with higher frequency in some critically unwell patient groups. The true positive BC rate was 10.9%, with pathogens most frequently isolated in older patients, those with a haematological condition or genitourinary source, and those admitted to inpatient wards. Hospital length of stay did not differ between patients with negative and patients with false positive BCs.

CONCLUSIONS

BC quality standards in the ED such as false positive rate <3% and single culture rate <20% are required to facilitate benchmarking and prospective quality improvement. The sensitivity and specificity of this common and critical test can be improved. Patient subgroups associated with poor-quality BC collection can be identified and should be a focus of future work.

Retrospective cohort study comparing two versus three blood culture sets in people who inject drugs

BACKGROUND

The current standard of drawing two vs three blood culture sets lacks adequate guidance. Because people who inject drugs are at higher risk for bacteraemia and life-threatening infection, consideration of a third blood culture becomes more important.

AIM

To investigate the risks and benefits of obtaining two versus three blood culture sets.

METHODS

Retrospective cohort study of adults who inject drugs at a multicentre catch-net hospital system from 2017-2022.

FINDINGS

998 people who inject drugs and 2278 blood culture sets were analysed. There were 1618 episodes with two blood culture sets and 660 episodes with three. A potential benefit of adding a third blood culture was seen in 30 (4.5%) episodes. However, only 13 (2.0%) episodes showed pathogen-identifying benefit, as 17 (2.6%) involved known inadequately treated infections or the same pathogen in another culture. The number of blood culture sets needed to achieve diagnostic benefit was 51. There were more contaminants for three blood culture sets (65, 9.8%) than for two (114, 7.0%) (p < 0.00001). By adding a third blood culture, the risk of a contaminant increased by 39.7%; the number of blood culture sets needed to find a contaminant was 36. Of 122 episodes with only contaminants and available for analysis, 111 (91.0%) experienced at least one complication. 33 (27.0%) patients experienced either prolonged admission, readmission, or unnecessary antibiotic administration.

CONCLUSIONS

The benefits of possibly isolating a pathogen from a third blood culture set do not universally outweigh the risks for contaminant growth for people who inject drugs. A third blood culture should be considered in specific clinical scenarios (i.e. inadequately treated endocarditis and osteomyelitis).

Impact of Blood Culture Contamination on Antibiotic Use, Resource Utilization, and Clinical Outcomes: A Retrospective Cohort Study in Dutch and US Hospitals

Background

Blood culture contamination (BCC) has been associated with prolonged antibiotic use (AU) and increased health care utilization; however, this has not been widely reevaluated in the era of increased attention to antibiotic stewardship. We evaluated the impact of BCC on AU, resource utilization, and length of stay in Dutch and US patients.

Methods

This retrospective observational study examined adults admitted to 2 hospitals in the Netherlands and 5 hospitals in the United States undergoing ≥2 blood culture (BC) sets. Exclusion criteria included neutropenia, no hospital admission, or death within 48 hours of hospitalization. The impact of BCC on clinical outcomes-overall inpatient days of antibiotic therapy, test utilization, length of stay, and mortality-was determined via a multivariable regression model.

Results

An overall 22 927 patient admissions were evaluated: 650 (4.1%) and 339 (4.8%) with BCC and 11 437 (71.8%) and 4648 (66.3%) with negative BC results from the Netherlands and the United States, respectively. Dutch and US patients with BCC had a mean ± SE 1.74 ± 0.27 (P < .001) and 1.58 ± 0.45 (P < .001) more days of antibiotic therapy than patients with negative BC results. They also had 0.6 ± 0.1 (P < .001) more BCs drawn. Dutch but not US patients with BCC had longer hospital stays (3.36 days; P < .001). There was no difference in mortality between groups in either cohort. AU remained higher in US but not Dutch patients with BCC in a subanalysis limited to BC obtained within the first 24 hours of admission.

Conclusions

BCC remains associated with higher inpatient AU and health care utilization as compared with patients with negative BC results, although the impact on these outcomes differs by country.

Sites of blood collection and topical disinfectants associated with contaminated cultures: An ambidirectional cohort study

Background

We aimed to determine whether puncture sites for blood sampling and topical disinfectants are associated with rates of contaminated blood cultures in the emergency department (ED) of a single institution.

Methods

This single-center, ambidirectional cohort study of 548 consecutive patients ≥20 years of age was performed in the ED of a university hospital in Japan over a 13-month period. Pairs of blood samples were collected for aerobic and anaerobic cultures from patients in the ED. Physicians selected puncture sites and topical disinfectants according to their personal preference.

Results

Potential contamination was identified in 110 of the 548 patients (20.1%). One hundred fourteen (20.8%) patients showed true-positive results for bacteremia, and 324 (59.1%) patients showed true-negative results. Multivariate analysis revealed more frequent contamination when puncture sites were disinfected with povidone-iodine (PVI) than with alcohol/chlorhexidine (ACHX) (adjusted risk difference, 19.1%; 95% confidence interval [CI]), 15.7-22.6; p < 0.001). In terms of blood collection sites, femoral and central venous (CV) catheter with PVI disinfection showed more frequent contamination than venous sites with ACHX (adjusted risk differences: 26.6%, 95% CI 21.3-31.9, p < 0.001 and 41.1%, 95% CI 22.2-59.9, p < 0.001, respectively).

Conclusion

Rates of contaminated blood cultures were significantly higher when blood was collected from the CV catheter or femoral sites with PVI as the topical disinfectant.

A clinical decision rule to rule out bloodstream infection in the emergency department: retrospective multicentric observational cohort study

BACKGROUND

We aimed to identify patients at low risk of bloodstream infection (BSI) in the ED.

METHODS

We derived and validated a prediction model to rule out BSI in the ED without the need for laboratory testing by determining variables associated with a positive blood culture (BC) and assigned points according to regression coefficients. This retrospective study included adult patients suspected of having BSI (defined by at least one BC collection) from two European ED between 1 January 2017 and 31 December 2019. The primary end point was the BSI rate in the validation cohort for patients with a negative Bacteremia Rule Out Criteria (BAROC) score. The effect of adding laboratory variables to the model was evaluated as a second step in a two-step diagnostic strategy.

RESULTS

We analysed 2580 patients with a mean age of 64 years±21, of whom 46.1% were women. The derived BAROC score comprises 12 categorical clinical variables. In the validation cohort, it safely ruled out BSI without BCs in 9% (58/648) of patients with a sensitivity of 100% (95% CI 95% to 100%), a specificity of 10% (95% CI 8% to 13%) and a negative predictive value of 100% (95% CI 94% to 100%). Adding laboratory variables (creatinine ≥177 µmol/L (2.0 mg/dL), platelet count ≤150 000/mm3 and neutrophil count ≥12 000/mm3) to the model, ruled out BSI in 10.2% (58/570) of remaining patients who had been positive on the BAROC score. The BAROC score with laboratory results had a sensitivity of 100% (95% CI 94% to 100%), specificity of 11% (95% CI 9% to 14%) and negative predictive value of 100% (95% CI 94 to 100%). In the validation cohort, there was no evidence of a difference in discrimination between the area under the receiver operating characteristic for BAROC score with versus without laboratory testing (p=0.6).

CONCLUSION

The BAROC score safely identified patients at low risk of BSI and may reduce BC collection in the ED without the need for laboratory testing.

The impact of the COVID-19 pandemic on blood culture practices and bloodstream infections

IMPORTANCE

Bacterial infections are a significant cause of morbidity and mortality worldwide. In the wake of the COVID-19 pandemic, previous studies have demonstrated pandemic-related shifts in the epidemiology of bacterial bloodstream infections (BSIs) in the general population and in specific hospital systems. Our study uses a large, comprehensive data set stratified by setting [community, long-term care (LTC), and hospital] to uniquely demonstrate how the effect of the COVID-19 pandemic on BSIs and testing practices varies by healthcare setting. We showed that, while the number of false-positive blood culture results generally increased during the pandemic, this effect did not apply to hospitalized patients. We also found that many infections were likely under-recognized in patients in the community and in LTC, demonstrating the importance of maintaining healthcare for these groups during crises. Last, we found a decrease in infections caused by certain pathogens in the community, suggesting some secondary benefits of pandemic-related public health measures.

Application of Participatory Ergonomics to the Dissemination of a Quality Improvement Program for Optimizing Blood Culture Use

BACKGROUND

Blood cultures are overused in pediatric ICUs (PICUs), which may lead to unnecessary antibiotic use and antibiotic resistance. Using a participatory ergonomics (PE) approach, the authors disseminated a quality improvement (QI) program for optimizing blood culture use in PICUs to a national 14-hospital collaborative. The objective of this study was to evaluate the dissemination process and its impact on blood culture reduction.

METHODS

The PE approach emphasized three key principles (stakeholder participation, application of human factors and ergonomics knowledge and tools, and cross-site collaboration) with a six-step dissemination process. Data on interactions between sites and the coordinating team and site experiences with the dissemination process were collected using site diaries and semiannual surveys with local QI teams, respectively, and correlated with the site-specific change in blood culture rates.

RESULTS

Overall, participating sites were able to successfully implement the program and reduced their blood culture rates from 149.4 blood cultures per 1,000 patient-days/month before implementation to 100.5 blood cultures per 1,000 patient-days/month after implementation, corresponding to a 32.7% relative reduction (p < 0.001). Variations in the dissemination process, as well as in local interventions and implementation strategies, were observed across sites. Site-specific changes in blood culture rates were weakly negatively correlated with the number of preintervention interactions with the coordinating team (p = 0.057) but not correlated with their experiences with the six domains of the dissemination process or their interventions.

CONCLUSIONS

The authors applied a PE approach to disseminate a QI program for optimizing PICU blood culture use to a multisite collaborative. Working with local stakeholders, participating sites tailored their interventions and implementation processes and achieved the goal of reducing blood culture use.

Getting to zero: Impact of a device to reduce blood culture contamination and false-positive central-line-associated bloodstream infections

OBJECTIVE

To assess the impact of initial specimen diversion device (ISDD) on inpatient and emergency department blood culture contamination (BCC), central-line-associated bloodstream infection (CLABSI) standardized infection ratios (SIRs), and antibiotic administration.

DESIGN

Single-center quasi-experimental prospective cohort study wherein phlebotomists used traditional venipuncture with or without the ISDD while registered nurses (RNs) used traditional venipuncture.

METHOD

BCC events among phlebotomists and RNs were observed and compared from March 17, 2019, through January 21, 2020, defined by contaminant detection in 1 of 4 bottles for matched sets or 1 of 2 bottles in both subsets for coagulase negative staphylococci. CLABSIs throughout this period were recorded and SIRs were calculated. Enhanced oversight took place through July 21, 2019, with chart review assessing antibiotic use for patients with possible BCC.

RESULTS

Overall, 24% of blood cultures obtained were from patients in intensive care. Phlebotomists using traditional venipuncture (n = 4,759) had a 2.3% BCC rate; phlebotomists using the ISDD (n = 11,202) had a 0% BCC rate. RNs drew 7,411 BCs with a 0.8% BCC rate. The CLABSI SIR was decreased from 1.103 in 2017 and 0.658 in 2018 to 0.439 in 2019. The CLABSI incidence was 33%-64% of predicted value for each 2019 quarter. This range fell to 18%-37% after the exclusion of likely false-positive results. Among 42 patients with possible BCC under enhanced oversight, 2 patients were treated with prolonged antibiotic courses.

CONCLUSIONS

ISDD use by phlebotomists was associated with BCC reduction and reduced false-positive CLABSI results. This patient-care quality improvement could constitute sustainable antibiotic stewardship expansion.

Impact of Rapid Identification and Stewardship Intervention on Coagulase-Negative Staphylococcus Bloodstream Infection

We investigated the impact of rapid diagnostic testing with and without algorithm-based stewardship recommendations on antibiotic use for bloodstream infection with coagulase-negative staphylococci. A significant reduction in antibiotic days of therapy was achieved in the stewardship intervention group that was not seen with rapid diagnostic testing alone.

Direct-from-Blood Detection of Pathogens: a Review of Technology and Challenges

Blood cultures have been the staple of clinical microbiology laboratories for well over half a century, but gaps remain in our ability to identify the causative agent in patients presenting with signs and symptoms of sepsis. Molecular technologies have revolutionized the clinical microbiology laboratory in many areas but have yet to present a viable alternative to blood cultures. There has been a recent surge of interest in utilizing novel approaches to address this challenge. In this minireview, I discuss whether molecular tools will finally give us the answers we need and the practical challenges of incorporating them into the diagnostic algorithm.

Central-line associated bloodstream infections in intensive care units before and after implementation of daily antiseptic bathing with chlorhexidine or octenidine: a post-hoc analysis of a cluster-randomised controlled trial

BACKGROUNDS

Antiseptic bathing did not reduce central-line (CL) associated bloodstream infection (CLABSI) rates in intensive care units (ICU) according to a recent cluster randomised controlled trial (cRCT). However, this analysis did not consider baseline infection rates. Our post-hoc analysis of this cRCT aimed to use a before-after comparison to examine the effect of daily bathing with chlorhexidine, octenidine or water and soap (control) on ICU-attributable CLABSI rates.

METHODS

A post-hoc analysis of a multi-center cRCT was done. ICUs that did not yet perform routine antiseptic bathing were randomly assigned to one of three study groups applying daily bathing with 2% chlorhexidine-impregnated cloths, 0.08% octenidine wash mitts or water and soap (control) for 12 months. Baseline data was assessed 12 months before the intervention started when all ICUs routinely used water and soap. Poisson regression and generalised estimating equation models were applied to identify changes of CLABSI rates per 1000 CL days between intervention and baseline periods in each study group.

RESULTS

The cRCT was conducted in 72 ICUs (24 per study group) including 76,139 patients in the baseline and 76,815 patients in the intervention period. In the chlorhexidine group, incidence density of CLABSI was reduced from 1.48 to 0.90 CLABSI per 1000 CL days comparing baseline versus intervention period (P = 0.0085). No reduction was observed in the octenidine group (1.26 versus 1.47 CLABSI per 1000 CL days, P = 0.8735) and the control group (1.20 versus 1.17, P = 0.3298). Adjusted incidence rate ratios (intervention versus baseline) were 0.63 (95%CI 0.46-0.87, P = 0.0172) in the chlorhexidine, 1.17 (95% CI 0.79-1.72, P = 0.5111) in the octenidine and 0.98 (95% CI 0.60-1.58, P = 0.9190) in the control group. Chlorhexidine bathing reduced CLABSI with gram-positive bacteria, mainly coagulase-negative staphylococci (CoNS).

CONCLUSIONS

In this post-hoc analysis of a cRCT, the application of 2% chlorhexidine-impregnated cloths reduced ICU-attributable CLABSI. This preventive effect of chlorhexidine was restricted to CLABSI caused by gram-positive pathogens (CoNS). In contrast, 0.08% octenidine wash mitts did not reduce CLABSI rates in ICUs. Trial registration Registration number DRKS00010475, registration date August 18, 2016.

The Impact of Initial Specimen Diversion Systems on Blood Culture Contamination

Blood culture contamination is associated with increased antimicrobial use, length of stay, and hospital cost. To address this problem, blood culture diversion has been developed as an additional measure to reduce contamination to targeted goals. Three different versions were proposed, including an open technique and 2 commercially available devices. This study aims to review the existing literature and analyze evidence for these 3 techniques.

Impact of a strategy based on unique blood culture sampling on contamination rate and detection of bloodstream infections in critically ill patients

BACKGROUND

Unique blood culture (UBC) has been proposed to limit the number of venipuncture and to decrease the risk of BC contaminations (BCC) without affecting their yield. We hypothesized that a multi-faceted program based on UBC in the ICU may reduce the rate of contaminants with a similar performance for bloodstream infections (BSI) identification.

METHODS

In a before and after design, we compared the proportion of BSI and BCC. A first 3-year period with multi-sampling (MS) strategy followed by a 4-month washout period, where staff received education and training for using UBC, and a 32-month period, where UBC was routinely used, while education and feedback were maintained. During the UBC period, a large volume of blood (40 mL) was sampled through a unique venipuncture with additional BC collections discouraged for 48 h.

RESULTS

Of the 4,491 patients included (35% female patients, mean age 62 years) 17,466 BC were collected. The mean volume of blood per bottle collected increased from 2.8 ± 1.8 mL to 8.2 ± 3.9 mL between the MS and UBC periods, P < 0.01. A 59.6% reduction (95% CI 56.7-62.3; P < 0.001) of BC bottles collected per week was observed between the MS and UBC periods. The rate of BCC per patient decreased between the two periods from 11.2% to 3.8% (73.4% reduction; P < 0.001) for the MS and UBC periods, P < 0.001. Meanwhile, the rate of BSI per patient remained stable at 13.2% and 13.2% for the MS and UBC periods, P = 0.98.

CONCLUSIONS

In ICU patients, a strategy based on UBC reduces the contamination rate of cultures without affecting their yield.

Determinants of Blood Culture Use in Critically Ill Children: A Multicenter Qualitative Study

Blood cultures are fundamental in diagnosing and treating sepsis in the pediatric intensive care unit (PICU), but practices vary widely. Overuse can lead to false positive results and unnecessary antibiotics. Specific factors underlying decisions about blood culture use and overuse are unknown. Therefore, we aimed to identify perceived determinants of blood culture use in the PICU.

Methods

We conducted semistructured interviews of clinicians (M.D., D.O., R.N., N.P., P.A.) from 6 PICUs who had participated in a quality improvement collaborative about blood culture practices. We developed interview questions by combining elements of the Consolidated Framework for Implementation Research and behavioral economics. We conducted telephone interviews, open-coded the transcripts, and used modified content analysis to determine key themes and mapped themes to elements of Consolidated Framework for Implementation Research and behavioral economics.

Results

We reached thematic saturation in 24 interviews. Seven core themes emerged across 3 Consolidated Framework for Implementation Research domains: individual characteristics [personal belief in the importance of blood cultures, the perception that blood cultures are a low-risk test]; inner setting [adherence to site-specific usual practices, site-specific overall approach to PICU care (collaborative versus hierarchical), influence of non-PICU clinicians on blood culture decisions]; and outer setting [patient-specific risk factors, sepsis guidelines]. In addition, outcome bias, default bias, and loss aversion emerged as salient behavioral economics concepts.

Conclusions

Determinants of blood culture use include individual clinician characteristics, inner setting, and outer setting, as well as default bias, outcome bias, and loss aversion. These determinants will now inform the development of candidate strategies to optimize culture practices.

Leveraging diagnostic stewardship within antimicrobial stewardship programmes

Novel diagnostic stewardship in infectious disease consists of interventions that modify ordering, processing, and reporting of diagnostic tests to provide the right test for the right patient, prompting the right action. The interventions work upstream and synergistically with traditional antimicrobial stewardship efforts. As diagnostic stewardship continues to gain public attention, it is critical that antimicrobial stewardship programmes not only learn how to effectively leverage diagnostic testing to improve antimicrobial use but also ensure that they are stakeholders and leaders in developing new diagnostic stewardship interventions within their institutions. This review will discuss the need for diagnostic and antimicrobial stewardship, the interplay of diagnostic and antimicrobial stewardship, evidence of benefit to antimicrobial stewardship programmes, and considerations for successfully engaging in diagnostic stewardship interventions. This article is part of the Antibiotic stewardship Special Issue: https://www.drugsincontext.com/special_issues/antimicrobial-stewardship-a-focus-on-the-need-for-moderation.

Test Performance and Potential Clinical Utility of the GenMark Dx ePlex Blood Culture Identification Gram-Negative Panel

The test performance and potential clinical utility of the ePlex blood culture identification Gram-negative (BCID-GN) panel was evaluated relative to matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry on bacterial isolates and conventional antimicrobial susceptibility testing. The majority (106/108, 98.1%) of GN bacteria identified by MALDI were on the BCID-GN panel, and valid tests (107/108, 99.1%) yielded results on average 26.7 h earlier. For all valid tests with on-panel organisms, the positive percent agreement was 102/105 (97.2%) with 3 false negatives and the negative percent agreement was 105/105. Chart review (n = 98) showed that in conjunction with Gram stain results, negative pan-Gram-positive (GP) markers provided the opportunity to discontinue GP antibiotic coverage in 63/98 (64.3%) cases on average 26.2 h earlier. Only 8/12 (66.7%) Enterobacterales isolates with resistance to third-generation cephalosporins harbored the CTX-M gene. In contrast, 8/8 CTX-M⁺ samples yielded a resistant isolate. Detection of 1 Stenotrophomonas maltophilia (18 h), 1 OXA23/48⁺ Acinetobacter baumannii (52.4 h), and 3 CTX-M⁺ Enterobacterales isolates on ineffective treatment (47.1 h) and 1 on suboptimal therapy (72.6 h) would have additionally enabled early antimicrobial optimization in 6/98 (6.1%) patients. IMPORTANCE The GenMark Dx ePlex rapid blood culture diagnostic system enables earlier time to identification of antimicrobial-resistant Gram-negative bacteria causing bloodstream infections. Its ability to rule out Gram-positive bacteria enabled early discontinuation of unnecessary antibiotics in 63/98 (64.3%) cases on average 26.2 h earlier. Detection of bacteria harboring the CTX-M gene as well as early identification of highly resistant bacteria such as Stenotrophomonas maltophilia and Acinetobacter baumannii enabled optimization of ineffective therapy in 6/98 (6.1%) patients. Its implementation in clinical microbiology laboratories optimizes therapy and improves patient care.

Increasing clinical impact and microbiological difficulties in diagnosing coagulase-negative staphylococci in infective endocarditis - a review starting from a series of cases

Coagulase-negative staphylococci (CoNS) are an emergent aetiology of infective endocarditis (IE) on native valves in previously healthy individuals, its presence is associated with prosthetic valves or with other cardiac implants. The identification of CoNS in cultures was customarily seen as contamination, but more recent epidemiological studies have revealed an increasing number of causative and virulent new CoNS species. Starting from two clinical cases of community-acquired CoNS IE on native valves, the review debates the difficulties in identifying CoNS as the causal pathogens, comprising differentiation of contamination from infection in IE, alongside the challenges raised by antibiotic resistance. Even if the risk of CoNS IE is more increased in subjects with prosthetic materials or other foreign devices and immunodeficiencies, native valve infections with these staphylococci are increasing and should be considered important pathogens in IE. Despite the lack of sensitive and specific tools to correctly differentiate contamination from infection in CoNS endocarditis, a comprehensive evaluation with clinical and paraclinical data accurately succeeds in establishing the diagnosis. The genetic profile of CoNS predisposes to antibiotic multi-resistance, making the treatment of IE challenging; the rapid identification of antibiotic susceptibility is essential to prescribe the appropriate therapy and improve outcomes.

Swedish emergency nurses' experiences of the preconditions for the safe collection of blood culture in the emergency department during the COVID-19 pandemic

AIM

To describe how Swedish emergency nurses experience the preconditions of providing safe care during the COVID-19 pandemic when collecting blood culture in the emergency department.

DESIGN

A qualitative exploratory design using content analysis with a manifest approach.

METHOD

Semi-structured interviews were conducted with 13 emergency nurses working in the emergency department.

RESULTS

The analysis resulted in one main category: unprecedented preconditions create extraordinary stress and jeopardize safe care when collecting blood culture. This main category includes four additional categories: organizational changes, challenges in the isolation room, heavy workload creates great stress, and continuous learning.

CONCLUSION

The COVID-19 outbreak has made the emergency department a workplace where constant changes of routines combined with new information and reorganization risk jeopardize safe care during blood culture sampling. Accordingly, high workload and stress have been identified as a reason for emergency nurses not following guidelines. It is therefore necessary to optimize the preconditions during blood culture sampling and identify situations where there are shortcomings.

Blood culture utilization practices among febrile and/or hypothermic inpatients

Background

Predictors associated with the decision of blood culture ordering among hospitalized patients with abnormal body temperature are still underexplored, particularly non-clinical factors. In this study, we evaluated the factors affecting blood culture ordering in febrile and hypothermic inpatients.

Methods

We performed a retrospective study of 15,788 adult inpatients with fever (≥ 38.3℃) or hypothermia (< 36.0℃) from January 2016 to December 2017. We evaluated the proportion of febrile and hypothermic episodes with an associated blood culture performed within 24h. Generalized Estimating Equations were used to determine independent predictors associated with blood culture ordering among febrile and hypothermic inpatients.

Results

We identified 21,383 abnormal body temperature episodes among 15,788 inpatients (13,093 febrile and 8,290 hypothermic episodes). Blood cultures were performed in 36.7% (7,850/ 21,383) of these episodes. Predictors for blood culture ordering among inpatients with abnormal body temperature included fever ≥ 39℃ (adjusted odd ratio [aOR] 4.17, 95% confident interval [CI] 3.91–4.46), fever (aOR 3.48, 95% CI 3.27–3.69), presence of a central venous catheter (aOR 1.36, 95% CI 1.30–1.43), systemic inflammatory response (SIRS) plus hypotension (aOR 1.33, 95% CI 1.26–1.40), SIRS (aOR 1.26, 95% CI 1.20–1.31), admission to stem cell transplant / medical oncology services (aOR 1.09, 95% CI 1.04–1.14), and detection of abnormal body temperature during night shift (aOR 1.06, 95% CI 1.03–1.09) or on the weekend (aOR 1.05, 95% CI 1.01–1.08).

Conclusion

Blood culture ordering for hospitalized patients with fever or hypothermia is multifactorial; both clinical and non-clinical factors. These wide variations and gaps in practices suggest opportunities to improve utilization patterns.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07748-x.

Effect of Blood Culture Contamination on Antibiotic Use in an Institution With Rapid Laboratory Methods and Phone-Based Clinical Follow-up of Blood Culture Results

In a multivariate analysis of 30 574 blood culture (BC) results, BC contamination was associated with only a small increase in antibiotic length of therapy compared to no-growth BCs (difference, 0.36 days [95% confidence interval, .05-.67]; P = .02). Stewardship processes at our institution appear to be effective in reducing the impact of BC contamination.

Initial Specimen Diversion Device Utilization Mitigates Blood Culture Contamination Across Regional Community Hospital and Acute Care Facility

A West Virginia regional community hospital incorporated an initial specimen diversion device (ISDD) into conventional blood culture protocol with the objective to bring the hospital-wide blood culture contamination (BCC) rate from a 3.06% preintervention rate to a target performance level below 1%. Emergency department staff, laboratory phlebotomists, and nursing staff on acute-critical care floors were trained on ISDD (Steripath Gen2, Magnolia Medical Technologies, Inc., Seattle, WA) operating procedure and utilized the device for blood culture sample collection with adult patients from September 2020 through April 2021. Of 5642 blood culture sets collected hospital-wide, 4631 were collected with the ISDD, whereas the remaining sets were collected via the conventional method. The ISDD BCC rate of 0.78% differed from the conventional method BCC rate of 4.06% observed during the intervention period (chi-squared test P < 0.00001). The ISDD group attained a sub-1% BCC rate to satisfy the intervention objective.

Multidrug-Resistant Bacteria Isolated from Blood Culture Samples in a Moroccan Tertiary Hospital: True Bacteremia or Contamination?

Purpose

To demonstrate the relevance of clinico-biological correlation in the interpretation of positive blood cultures (BC) for multidrug-resistant (MDR) bacteria, among adult and pediatric patients, in order to distinguish between true bacteremia (TB) and contaminations and to evaluate the impact on patient management.

Patients and Methods

This six-month study was conducted at Mohammed VI University Hospital in Marrakech. All MDR bacteria isolated from BCs carried out on hospitalized patients during this period were included. For each positive BC to MDR microorganism, demographic and clinical characteristics, laboratory findings, therapeutic and evolution data were collected.

Results

TB was considered in 157 (94.6%) of the 166 positive-culture episodes for MDR bacteria, while 9 (5.4%) were classified as false-positive. Contamination rate was 0.2% (9/3824). TB and contaminations occurred mainly in intensive care units (ICUs), with the neonatal ICU being the most concerned (p = 0.016). Clinical signs of sepsis were present in all TB patients, with a significant difference between the two groups (p = 0.000). CRP values were higher in the TB group (p = 0.000). The most isolated true pathogens were ESBL-producing Enterobacterales (50%) and carbapenem-resistant Enterobacterales (33.3%). They also predominated in contaminated BCs. Isolation of the same microorganism from other sites was significantly associated with TB (p = 0.012). In contrast to the contaminations group, the difference in the clinical course of TB patients, according to whether or not they received appropriate probabilistic antibiotics, was statistically significant (p = 0.000). These patients had longer hospital stays and longer durations of antibiotic therapy. The overall mortality rate was 39.6%.

Conclusion

Distinguishing between MDR-positive BCs representing clinically significant bacteremia or simple contamination requires a careful clinical, biological, and microbiological confrontation of each MDR positive BC in order to avoid unnecessary overuse of broad-spectrum antibiotics and thus reduce resistance selective pressure.

Implementation of Antibiotic Stewardship Improves the Quality of Blood Culture Diagnostics at an Intensive Care Unit of a University Hospital

Background: Bloodstream infections increase morbidity and mortality in hospitalized patients and pose a significant burden for health care systems worldwide. Optimal blood culture diagnostics are essential for early detection and specific treatment. After assessing the quality parameters at a surgical intensive care unit for six months, we implemented a diagnostic stewardship bundle (DSB) to optimize blood culture diagnostics and then reevaluated its effects after six months. Material and Methods: All patients ≥18 years old and on the ward were included: pre-DSB 137 and post-DSB 158. The standard quality parameters were defined as the number of blood culture sets per diagnostic episode (≥2), the rate of contamination (2–3%), the rate of positivity (5–15%), the collection site (≥1 venipuncture per episode) and the filling volume of the bottles (8–10 mL, only post-DSB). The DSB included an informational video, a standard operating procedure, and ready-to-use paper crates with three culture sets. Results: From pre- to post-interventional, the number of ≥2 culture sets per episode increased from 63.9% (257/402) to 81.3% (230/283), and venipunctures increased from 42.5% (171/402) to 77.4% (219/283). The positivity rate decreased from 15.1% (108/714) to 12.8% (83/650), as did the contamination rate (3.8% to 3.6%). The majority of the aerobic bottles were filled within the target range (255/471, 54.1%), but in 96.6%, the anaerobic bottles were overfilled (451/467). Conclusions: The implementation of DSB improved the quality parameters at the unit, thus optimizing the blood culture diagnostics. Further measures seem necessary to decrease the contamination rate and optimize bottle filling significantly.

Blood Culture Contamination: A Single General Hospital Experience of 2-Year Retrospective Study

In the event of blood culture contamination (BCC), blood culture (BC) needs to be repeated. This may delay appropriate treatment, prolong hospitalization and, consequently, increase its costs. The aim of the study was to assess the frequency of BCC and associated factors in a general hospital in Poland based on reports of BC in samples submitted for laboratory testing in 2019−2020. BCC is recognized when bacteria (especially those belonging to natural human microbiota) are isolated from a single sample and no clinical signs indicated infection. True positive BC is confirmed by the growth of bacteria in more than one set of blood samples with the corresponding clinical signs present. The structure of BC sets, microorganisms, and laboratory costs of BCC were analyzed. Out of 2274 total BC cases, 11.5% were true positive BC and 9.5% were BCC. Of all the BCC identified in the entire hospital, 72% was from Internal Medicine (IM) and Intensive Care Unit (ICU) combined. When single sets for BC were used in IM in 2020, the use increased to 85% compared with 2019 (p < 0.05). The predominant isolates were coagulase-negative staphylococci (84%). The estimated extra laboratory costs of BCC exceeded EUR 268,000. The BCC was a more serious problem than expected, including non-recommended using of single BC sets. Compliance with the BC collection procedure should be increased in order to reduce BCC and thus extra hospital costs.

Numbers and narratives: how qualitative methods can strengthen the science of paediatric antimicrobial stewardship

Antimicrobial and diagnostic stewardship initiatives have become increasingly important in paediatric settings. The value of qualitative approaches to conduct stewardship work in paediatric patients is being increasingly recognized. This article seeks to provide an introduction to basic elements of qualitative study designs and provide an overview of how these methods have successfully been applied to both antimicrobial and diagnostic stewardship work in paediatric patients. A multidisciplinary team of experts in paediatric infectious diseases, paediatric critical care and qualitative methods has written a perspective piece introducing readers to qualitative stewardship work in children, intended as an overview to highlight the importance of such methods and as a starting point for further work. We describe key differences between qualitative and quantitative methods, and the potential benefits of qualitative approaches. We present examples of qualitative research in five discrete topic areas of high relevance for paediatric stewardship work: provider attitudes; provider prescribing behaviours; stewardship in low-resource settings; parents' perspectives on stewardship; and stewardship work focusing on select high-risk patients. Finally, we explore the opportunities for multidisciplinary academic collaboration, incorporation of innovative scientific disciplines and young investigator growth through the use of qualitative research in paediatric stewardship. Qualitative approaches can bring rich insights and critically needed new information to antimicrobial and diagnostic stewardship efforts in children. Such methods are an important tool in the armamentarium against worsening antimicrobial resistance, and a major opportunity for investigators interested in moving the needle forward for stewardship in paediatric patients.

Diagnostic Stewardship in the Pediatric Intensive Care Unit

In the pediatric intensive care unit (PICU), clinicians encounter complex decision making, balancing the need to treat infections promptly against the potential harms of antibiotics. Diagnostic stewardship is an approach to optimize microbiology diagnostic test practices to reduce unnecessary antibiotic treatment. We review the evidence for diagnostic stewardship of blood, endotracheal, and urine cultures in the PICU. Clinicians should consider 3 questions applying diagnostic stewardship: (1) Does the patient have signs or symptoms of an infectious process? (2) What is the optimal diagnostic test available to evaluate for this infection? (3) How should the diagnostic specimen be collected to optimize results?

Patient-specific risk factors contributing to blood culture contamination

Objective:

Contaminated blood cultures result in extended hospital stays and unnecessary antibiotic therapy. Patient-specific factors associated with blood culture contamination remain largely unexplored. Identifying patients at higher risk of blood culture contamination could alert healthcare providers to take extra precautionary measures to limit contamination in these patients, and thereby prevent associated adverse outcomes. We sought to identify patient-related factors that contribute to blood culture contamination in hospitalized patients.

Design and setting:

We conducted a secondary data analysis of a retrospective cohort study at an academic medical center.

Patients:

Study participants included 19,255 adult patients who had blood culture(s) performed during a hospital admission between June 2014 and December 2016.

Methods:

Data were analyzed to evaluate risk factors for blood culture contamination using logistic regression.

Results:

Among adult patients, we identified 464 contaminated episodes and 11,010 negative blood-culture episodes. Chronic obstructive pulmonary disease (adjusted odds ratio [AOR], 1.67; 95% confidence interval [CI], 1.20–2.34) and stay in an intensive care unit (ICU) during an admission (AOR, 1.41; 95% CI, 1.14–1.74) were associated with blood culture contamination. Other risk factors included race, body mass index, and admission from the emergency department. Subgroup analyses of patients admitted from the emergency department showed similar results.

Conclusions:

We identified patient-specific factors that increase the odds of false-positive blood cultures. By introducing mitigation strategies to limit contamination in patients with these risk factors, it may be possible to reduce the adverse clinical impact of blood culture contamination.

Impact of sterile gloves on blood-culture contamination rates: A randomized clinical trial

BACKGROUND

Reducing the blood-culture contamination rate is a constant challenge for health services. This study aimed to analyze whether blood-culture (BC) collection using sterile gloves reduces the contamination rate when compared to the non-sterile gloves, and to compare baseline and intervention periods.

METHODS

A randomized clinical trial, performed in an intensive care unit in Brazil and paired in two groups: sterile (BCs obtained with modified sterile technique: only sterile gloves; no fenestrated drape or dedicated sterile collection kit) and clean (clean technique: usual care with non-sterile gloves). Two paired blood samples were obtained from each patient by trained and calibrated nurses. BCs were processed by conventional microbiological methods and the results were issued by blinded microbiologists.

RESULTS

There was no difference (P = 1.00) in the contamination rate of BC between the sterile (1%) and clean (1%) groups. However, there was a significant difference (P = 0.05; relative risk: 0.17; 95% confidence interval: 0.04-0.70) in the contamination rate between baseline (6.1%; 20/330) and intervention (1%; 2/200).

CONCLUSIONS

This study suggests that the aseptic care provided in obtaining samples is more important than the sterile technique itself, and highlights the value of standardizing the practices, qualification and calibration of phlebotomists.

Diagnostic Stewardship: Appropriate Testing and Judicious Treatments

Diagnostic stewardship encompasses the entire diagnosis-to-treatment paradigm in the intensive care unit (ICU). Initially born of the antimicrobial stewardship movement, contemporary diagnostic stewardship aims to promote timely and appropriate diagnostic testing that directly links to management decisions. In the stewardship framework, excessive diagnostic testing in low probability cases is discouraged due to its tendency to generate false-positive results, which have their own downstream consequences. Though the evidence basis for diagnostic stewardship initiatives in the ICU is nascent and largely limited to retrospective analyses, available literature generally suggests that these initiatives are safe, feasible, and associated with similar patient outcomes. As diagnostic testing of critically ill patients becomes increasingly sophisticated in the ensuing decade, a stewardship mindset will aid bedside clinicians in interpreting and incorporating new diagnostic strategies in the ICU.

Impact of Direct From Blood Culture Identification of Pathogens Paired With Antimicrobial Stewardship Interventions in a Pediatric Hospital

OBJECTIVE

Identification of organisms directly from positive blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has the potential for improved clinical outcomes through earlier organism identification and shorter time to appropriate clinical intervention. The uses of this technology in pediatric patients and its impact in this patient population have not been well described.

METHODS

Direct from positive blood culture organism identification via MALDI-TOF was implemented in September 2019. A quality improvement project was performed to assess its impact on admissions for contaminant blood cultures and time to effective and optimal antimicrobials and clinical decision-making. A pre- and post-implementation retrospective review for consecutive September through February time periods, was conducted on patients with positive monomicrobial blood cultures. Statistics were evaluated using Mann-Whitney U and χ² tests.

RESULTS

One hundred nineteen patients with 131 unique blood cultures (65 in pre- and 66 in post-implementation) were identified. Time to identification was shorter, median 35.4 hours (IQR, 22.7-54.3) versus 42.3 hours (IQR, 36.5-49) in post- and pre-groups, respectively (p = 0.02). Patients were less likely to be admitted for a contaminated blood culture in the post-implementation, 26% versus 11% in the pre-implementation (p = 0.03) group. In patients treated for bacteremia, there was a shorter time to optimal therapy from Gram stain reporting in the post-implementation (median 42.7 hours [IQR, 27.2-72]) versus pre-implementation (median 60.8 hours [IQR, 42.9-80.6]) (p = 0.03).

CONCLUSIONS

Direct from positive blood culture identification by MALDI-TOF decreased time to effective and optimal antimicrobials and decreased unnecessary admission in pediatric patients for contaminated blood cultures.

Initial Specimen Diversion Device® Reduces Blood Culture Contamination and Vancomycin Use in Academic Medical Center

BACKGROUND

In suspected bloodstream infections, accurate blood culture results are critical to timely diagnoses and appropriate antibiotic administration.

AIM

An Initial Specimen Diversion Device®, Steripath®, (Magnolia Medical Technologies, Seattle, WA) was evaluated for efficacy in reducing blood culture contamination at Brooke Army Medical Center (6.8% six-month contamination rate prior to intervention) in a six-month quality improvement project.

METHODS

Blood cultures in the emergency department were collected using either Steripath® or the standard method. 20 mL of blood was cultured into an aerobic and anaerobic medium and incubated for five days using an automated microbial detection system immediately after collection. Positive bottles were Gram stained and plated. Rapid molecular PCR identification was performed on all first positive bottles within a blood culture set for each admission or ED visit. Speciation was deduced during antimicrobial sensitivity testing using the Vitek-2 instrument.

FINDINGS

Seven (7/1016, 0.69%) contamination events occurred when using Steripath® vs. 53 (53/800, 6.6%) contamination events when using the standard method. Steripath® use was associated with a 90% lower incidence of blood culture contamination vs. the standard method. Post-study, Steripath® use was implemented as standard practice hospital-wide, and a retrospective data analysis attributed a 31.4% decrease in vancomycin days of therapy to Steripath® adoption.

CONCLUSION

Using Steripath® significantly decreased blood culture contamination events for bacterial bloodstream infections compared to the standard method. Subsequent adoption of Steripath® reduced overall vancomycin usage. With widescale implementation Steripath® could bolster antibiotic stewardship, mitigating antibiotic resistance caused by unnecessary antibacterial treatments.

Use of a Sterile Collection Process to Reduce Contaminated Peripheral Blood Cultures

BACKGROUND

Contaminated blood cultures pose a significant burden by subjecting children to unnecessary testing, procedures, and antibiotics and increasing health care costs. The aim of our quality improvement (QI) initiative was to decrease the percentage of contaminated peripheral blood cultures in our pediatric emergency department (ED) from an average of 6.7% to <3% over a 16-month period.

METHODS

The QI initiative was implemented in the pediatric ED of a tertiary care children's hospital. Interventions included change of the peripheral blood culture collection from a clean to a sterile process, nursing education, and individualized feedback. The primary outcome measure was the percentage of contaminated peripheral blood cultures. The process measure was the percentage of nurses who completed 75% to 100% of the steps of the sterile collection process, as measured by self-reporting in audit cards. The balancing measures were time from antibiotic ordering to time of administration and ED length of stay.

RESULTS

We decreased the percentage of contaminated peripheral blood cultures threefold from a baseline (June 2, 2018, to December 31, 2018) of 6.7% to 2.1% during the intervention period (January 1, 2019, to April 30, 2020). Ninety-eight percent of nurses who completed audit cards reported performing 75% to 100% of the steps of the new sterile process. There was no significant difference in the average time from antibiotic ordering to antibiotic administration or ED length of stay between the baseline and intervention periods.

CONCLUSIONS

Use of a sterile blood culture collection process, in addition to nursing education and individualized feedback, is an effective method to decrease peripheral blood culture contamination rates in a pediatric ED.

Regression discontinuity of blood culture contamination rate after changing of disinfectants: retrospective observational study

Blood cultures are indispensable for detecting life-threatening bacteremia. Little is known about associations between contamination rates and topical disinfectants for blood collection in adults. We sought to determine whether a change in topical disinfectants was associated with the rates of contaminated blood cultures in the emergency department of a single institution. This single-center, retrospective observational study of consecutive patients aged 20 years or older was conducted in the emergency department (ED) of a university hospital in Japan between August 1, 2018 and September 30, 2020. Pairs of blood samples were collected for aerobic and anaerobic culture from the patients in the ED. Physicians selected topical disinfectants according to their personal preference before September 1, 2019; alcohol/chlorhexidine gluconate (ACHX) was mandatory thereafter, unless the patient was allergic to alcohol. Regression discontinuity analysis was used to detect the effect of the mandatory usage of ACHX on rates of contaminated blood cultures. We collected 2141 blood culture samples from 1097 patients and found 164 (7.7%) potentially contaminated blood cultures. Among these, 445 (20.8%) were true bacteremia and 1532 (71.6%) were true negatives. Puncture site disinfection was performed with ACHX for 1345 (62.8%) cases and with povidone-iodine (PVI) for 767 (35.8%) cases. The regression discontinuity analysis showed that mandatory ACHX usage was significantly associated with lower rates of contaminated blood cultures by 9.6% (95% confidence interval (CI): 5.0%–14.2%, P < 0.001). Rates of contaminated blood cultures were significantly lower when ACHX was used as the topical disinfectant.

Clinical Nurse Specialist Practice: Impact on Emergency Department Blood Culture Contamination

PURPOSE/OBJECTIVES

Blood culture collection is a common procedure performed in emergency departments. Rate of blood culture contamination is a metric that is tracked by organizations to ensure appropriate treatment for patients suspected of having bacteremia and ensure appropriate use of hospital resources. A team of nurses and technicians undertook a quality improvement project to decrease blood culture contamination rates in a suburban emergency department.

DESCRIPTION OF THE PROJECT

The project included use of standardized blood culture collection kits, creation of a dedicated collection team, and implementation of a new blood culture collection device.

OUTCOME

Through this work, blood culture contamination rates decreased from greater than 3.0% to less than 1.5% consistently for nearly 24 months.

CONCLUSIONS

Providing feedback and continued monitoring has made this quality improvement initiative a success for the department and the organization and has resulted in cost savings of nearly 2 million dollars.

Simple indictor of increased blood culture contamination rate by detection of coagulase-negative staphylococci

Coagulase-negative staphylococci (CoNS) are the most frequent contaminating bacteria; therefore, we aimed to investigate an indicator of CoNS to predict the increase in blood culture contamination rate (ConR). We performed a retrospective study of selected patients, who underwent blood culture testing. Contamination was defined as the presence of either one of two or more sets of skin-resident bacteria, except for cases with a low likelihood of contamination based on clinical aspects. We calculated the monthly ConR [(total number of contaminated cases per month)/(total number of blood culture sets collected per month) × 100] and analysed the ConR prediction ability using the following four indicators: the number of CoNS-positive sets of blood cultures, cases with at least one CoNS-positive blood culture set, cases with only one CoNS-positive blood culture set, and cases of contamination by CoNS. Cases with CoNS-positive blood cultures correlated with ConR (r = 0.85). Although the area under the receiver operating characteristic curve for the number of cases with ConR ≥ 2.5 differed significantly from that of the number of cases contaminated by CoNS, the negative predictive value was high, reaching up to 95.5% (95% confidential interval 87.3–99.1). The number of CoNS-positive cases could help predict an increase in ConR ≥ 2.5.

Consensus Recommendations for Blood Culture Use in Critically Ill Children Using a Modified Delphi Approach

OBJECTIVES

Blood cultures are fundamental in evaluating for sepsis, but excessive cultures can lead to false-positive results and unnecessary antibiotics. Our objective was to create consensus recommendations focusing on when to safely avoid blood cultures in PICU patients.

DESIGN

A panel of 29 multidisciplinary experts engaged in a two-part modified Delphi process. Round 1 consisted of a literature summary and an electronic survey sent to invited participants. In the survey, participants rated a series of recommendations about when to avoid blood cultures on five-point Likert scale. Consensus was achieved for the recommendation(s) if 75% of respondents chose a score of 4 or 5, and these were included in the final recommendations. Any recommendations that did not meet these a priori criteria for consensus were discussed during the in-person expert panel review (Round 2). Round 2 was facilitated by an independent expert in consensus methodology. After a review of the survey results, comments from round 1, and group discussion, the panelists voted on these recommendations in real-time.

SETTING

Experts' institutions; in-person discussion in Baltimore, MD.

SUBJECTS

Experts in pediatric critical care, infectious diseases, nephrology, oncology, and laboratory medicine.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 27 original recommendations, 18 met criteria for achieving consensus in Round 1; some were modified for clarity or condensed from multiple into single recommendations during Round 2. The remaining nine recommendations were discussed and modified until consensus was achieved during Round 2, which had 26 real-time voting participants. The final document contains 19 recommendations.

CONCLUSIONS

Using a modified Delphi process, we created consensus recommendations on when to avoid blood cultures and prevent overuse in the PICU. These recommendations are a critical step in disseminating diagnostic stewardship on a wider scale in critically ill children.

Diagnosing hospital bacteraemia in the framework of predictive, preventive and personalised medicine using electronic health records and machine learning classifiers

Background

The bacteraemia prediction is relevant because sepsis is one of the most important causes of morbidity and mortality. Bacteraemia prognosis primarily depends on a rapid diagnosis. The bacteraemia prediction would shorten up to 6 days the diagnosis, and, in conjunction with individual patient variables, should be considered to start the early administration of personalised antibiotic treatment and medical services, the election of specific diagnostic techniques and the determination of additional treatments, such as surgery, that would prevent subsequent complications. Machine learning techniques could help physicians make these informed decisions by predicting bacteraemia using the data already available in electronic hospital records.

Objective

This study presents the application of machine learning techniques to these records to predict the blood culture's outcome, which would reduce the lag in starting a personalised antibiotic treatment and the medical costs associated with erroneous treatments due to conservative assumptions about blood culture outcomes.

Methods

Six supervised classifiers were created using three machine learning techniques, Support Vector Machine, Random Forest and K-Nearest Neighbours, on the electronic health records of hospital patients. The best approach to handle missing data was chosen and, for each machine learning technique, two classification models were created: the first uses the features known at the time of blood extraction, whereas the second uses four extra features revealed during the blood culture.

Results

The six classifiers were trained and tested using a dataset of 4357 patients with 117 features per patient. The models obtain predictions that, for the best case, are up to a state-of-the-art accuracy of 85.9%, a sensitivity of 87.4% and an AUC of 0.93.

Conclusions

Our results provide cutting-edge metrics of interest in predictive medical models with values that exceed the medical practice threshold and previous results in the literature using classical modelling techniques in specific types of bacteraemia. Additionally, the consistency of results is reasserted because the three classifiers' importance ranking shows similar features that coincide with those that physicians use in their manual heuristics. Therefore, the efficacy of these machine learning techniques confirms their viability to assist in the aims of predictive and personalised medicine once the disease presents bacteraemia-compatible symptoms and to assist in improving the healthcare economy.

Diagnostic yield of routine daily blood culture in patients on veno-arterial extracorporeal membrane oxygenation

BACKGROUND

Bloodstream infections (BSIs) are frequent on veno-arterial extracorporeal membrane oxygenation (V-A ECMO). Performing routine blood cultures (BCs) may identify early paucisymptomatic BSIs. We investigated the contribution of systematic daily BCs to detect BSIs on V-A ECMO.

METHODS

This was a retrospective study including all adult patients requiring V-A ECMO and surviving more than 24 h. Our protocol included routine daily BCs, from V-A ECMO insertion up to 5 days after withdrawal; other BCs were performed on-demand.

RESULTS

On the 150 V-A ECMO included, 2146 BCs were performed (1162 routine and 984 on-demand BCs); 190 (9%) were positive, including 68 contaminants. Fifty-one (4%) routine BCs revealed BSIs; meanwhile, 71 (7%) on-demand BCs revealed BSIs (p = 0.005). Performing routine BCs was negatively associated with BSIs diagnosis (OR 0.55, 95% CI [0.38; 0.81], p = 0.002). However, 16 (31%) BSIs diagnosed by routine BCs would have been missed by on-demand BCs. Independent variables for BSIs diagnosis after routine BCs were: V-A ECMO for cardiac graft failure (OR 2.43, 95% CI [1.20; 4.92], p = 0.013) and sampling with on-going antimicrobial therapy (OR 2.15, 95% CI [1.08; 4.27], p = 0.029) or renal replacement therapy (OR 2.05, 95% CI [1.10; 3.81], p = 0.008). Without these three conditions, only two BSIs diagnosed with routine BCs would have been missed by on-demand BCs sampling.

CONCLUSIONS

Although routine daily BCs are less effective than on-demand BCs and expose to contamination and inappropriate antimicrobial therapy, a policy restricted to on-demand BCs would omit a significant proportion of BSIs. This argues for a tailored approach to routine daily BCs on V-A ECMO, based on risk factors for positivity.

The Diagnostic Yield of Routine Admission Blood Cultures in Critically Ill Patients

OBJECTIVES

Although the Surviving Sepsis Campaign bundle recommends obtaining blood cultures within 1 hour of sepsis recognition, adherence is suboptimal in many settings. We, therefore, implemented routine blood culture collection for all nonelective ICU admissions (regardless of infection suspicion) and evaluated its diagnostic yield.

DESIGN

A before-after analysis.

SETTING

A mixed-ICU of a tertiary care hospital in the Netherlands.

PATIENTS

Patients acutely admitted to the ICU between January 2015 and December 2018.

MEASUREMENTS AND MAIN RESULTS

Automatic orders for collecting a single set of blood cultures immediately upon ICU admission were implemented on January 1, 2017. Blood culture results and the impact of contaminated blood cultures were compared for 2015-2016 (before period) and 2017-2018 (after period). Positive blood cultures were categorized as bloodstream infection or contamination. Blood cultures were obtained in 573 of 1,775 patients (32.3%) and in 1,582 of 1,871 patients (84.5%) in the before and after periods, respectively (p < 0.0001), and bloodstream infection was diagnosed in 95 patients (5.4%) and 154 patients (8.2%) in both study periods (relative risk 1.5; 95% CI 1.2-2.0; p = 0.0006). The estimated number needed to culture for one additional patient with bloodstream infection was 17. Blood culture contamination occurred in 40 patients (2.3%) and 180 patients (9.6%) in the before period and after period, respectively (relative risk 4.3; 95% CI 3.0-6.0; p < 0.0001). Rate of vancomycin use or presumed episodes of catheter-related bloodstream infections treated with antibiotics did not differ between both study periods.

CONCLUSIONS

Implementation of routine blood cultures was associated with a 1.5-fold increase of detected bloodstream infection. The 4.3-fold increase in contaminated blood cultures was not associated with an increase in vancomycin use in the ICU.

A Quality Improvement Initiative to Reduce Blood Culture Contamination in the Neonatal Unit

Peripheral blood culture contamination (BCC) can lead to an initiation of unnecessary antimicrobial treatment, further laboratory tests, increased length of stay, and increased costs. This study describes a 12-month quality improvement (QI) program to reduce the BCC rate in a neonatal unit by 50%.

Methods

The QI team focused on standardizing processes to align with best practices using process mapping and cause and effect diagrams. Plan-Do-Study-Act (PDSA) 1: inoculation of blood culture bottles with the introduction of transfer device; PDSA 2: preparation of the skin for peripheral intravenous cannula insertion; PDSA 3: aseptic technique education package; and PDSA 4: optimizing blood volume of blood collected for culture. The team used statistical process control methodology to detect special cause variation.

Results

Compliance with the standard processes as part of PSDA 1 improved from a mean level of 50% to 100% and for PDSA 2 improved from a mean level of 50% to 95%. After implementation of PDSA 3, scores on a relevant knowledge test increased from a mean of 39% (pretraining test; n = 10) to 92% (posttraining test; n = 10) (P < 0.001). Postimplementation of the processes for PDSA 4, a minimum of 1 mL was collected in 94% of blood culture collection events (n = 450) (mean 1.1 mL; range 0.5-3.5 mL). Special cause variation occurred after the implementation of the PDSA cycles. During the baseline period, the BCC rate was 2.0% and decreased to 1.0% postinterventions implementation.

Conclusions

Interventions focused on standardizing practices around collection of blood cultures in neonates were associated with fewer contaminants.This study is reported according to the SQUIRE 2.0 guidelines.

Modification of Blood Test Draw Order to Reduce Blood Culture Contamination: A Randomized Clinical Trial

BACKGROUND

Blood culture contamination leads to unnecessary interventions and costs. It may be caused by bacteria in deep skin structures unsusceptible to surface decontamination. This study was designed to test whether diversion of blood obtained at venipuncture into a lithium heparin tube prior to aspiration of blood culture reduces contamination.

METHODS

The order of blood draws for biochemistry and blood cultures was randomized. Following standard disinfection and venipuncture, blood was either aspirated into a sterile lithium heparin tube before blood culture bottles (diversion group) or blood cultures first and then lithium heparin tube (control group). All study personnel were blinded with the exception of the phlebotomist.

RESULTS

After exclusions, 970 blood culture/biochemistry sets were analyzed. Contamination occurred in 24 of 480 (5.0%) control vs 10 of 490 (2.0%) diversion group cultures (P = .01). True pathogens were identified in 26 of 480 (5.4%) control vs 18 of 490 (3.7%) diversion cultures (P = .22). Despite randomization, demographic differences were apparent between the 2 groups. A post hoc analysis of 637 cultures from 610 medical patients admitted from home neutralized demographic differences. Culture contamination remained more frequent in the control vs diversion group (17/312 [5%] vs 7/325 [2%]; P = .03). Fewer diversion group patients were admitted to hospital (control: 200/299 [66.9%] vs diversion: 182/311 [58.5%]; P = .03), and length of stay was shorter (control: 30 hours [interquartile range {IQR}, 6-122] vs diversion: 22 [IQR, 5-97]; P = .02).

CONCLUSIONS

Use of lithium heparin tubes for diversion prior to obtaining blood cultures led to a 60% decrease in contamination. This technique is easy and inexpensive and might decrease overall hospital length of stay.

CLINICAL TRIALS REGISTRATION

NCT03966534.

Risk factors and clinical outcomes associated with blood culture contamination

OBJECTIVE

To determine patient-specific risk factors and clinical outcomes associated with contaminated blood cultures.

DESIGN

A single-center, retrospective case-control risk factor and clinical outcome analysis performed on inpatients with blood cultures collected in the emergency department, 2014-2018. Patients with contaminated blood cultures (cases) were compared to patients with negative blood cultures (controls).

SETTING

A 509-bed tertiary-care university hospital.

METHODS

Risk factors independently associated with blood-culture contamination were determined using multivariable logistic regression. The impacts of contamination on clinical outcomes were assessed using linear regression, logistic regression, and generalized linear model with γ log link.

RESULTS

Of 13,782 blood cultures, 1,504 (10.9%) true positives were excluded, leaving 1,012 (7.3%) cases and 11,266 (81.7%) controls. The following factors were independently associated with blood-culture contamination: increasing age (adjusted odds ratio [aOR], 1.01; 95% confidence interval [CI], 1.01-1.01), black race (aOR, 1.32; 95% CI, 1.15-1.51), increased body mass index (BMI; aOR, 1.01; 95% CI, 1.00-1.02), chronic obstructive pulmonary disease (aOR, 1.16; 95% CI, 1.02-1.33), paralysis (aOR 1.64; 95% CI, 1.26-2.14) and sepsis plus shock (aOR, 1.26; 95% CI, 1.07-1.49). After controlling for age, race, BMI, and sepsis, blood-culture contamination increased length of stay (LOS; β = 1.24 ± 0.24; P < .0001), length of antibiotic treatment (LOT; β = 1.01 ± 0.20; P < .001), hospital charges (β = 0.22 ± 0.03; P < .0001), acute kidney injury (AKI; aOR, 1.60; 95% CI, 1.40-1.83), echocardiogram orders (aOR, 1.51; 95% CI, 1.30-1.75) and in-hospital mortality (aOR, 1.69; 95% CI, 1.31-2.16).

CONCLUSIONS

These unique risk factors identify high-risk individuals for blood-culture contamination. After controlling for confounders, contamination significantly increased LOS, LOT, hospital charges, AKI, echocardiograms, and in-hospital mortality.

Sites of blood collection and topical antiseptics associated with contaminated cultures: prospective observational study

We aimed to determine whether puncture sites for blood sampling and topical disinfectants are associated with rates of contaminated blood cultures in the emergency department (ED) of a single institution. This single-center, prospective observational study of 249 consecutive patients aged ≥ 20 years proceeded in the ED of a university hospital in Japan during 6 months. Pairs of blood samples were collected for aerobic and anaerobic culture from all patients in the ED. Physicians selected puncture sites and topical disinfectants according to their personal preference. We found 50 (20.1%) patients with potentially contaminated blood cultures. Fifty-six (22.5%) patients were true bacteremia and 143 (57.4%) patients were true negatives. Multivariate analysis associated more frequent contamination when puncture sites were disinfected with povidone-iodine than with alcohol/chlorhexidine (adjusted risk difference, 12.9%; 95% confidence interval [CI] 8.8–16.9; P < 0.001). Sites of blood collection were also associated with contamination. Femoral and central venous with other sites were associated with contamination more frequently than venous sites (adjusted risk difference), 13.1% (95% CI 8.2–17.9; P < 0.001]) vs. 17.3% (95% CI 3.6–31.0; P = 0.013). Rates of contaminated blood cultures were significantly higher when blood was collected from femoral sites and when povidone-iodine was the topical antiseptic.

Blood culture quality assurance: what Australasian laboratories are measuring and opportunities for improvement

Blood cultures are among the most important specimen types received and processed by the microbiology laboratory. Several publications list which variables should be measured to ensure quality. We undertook a qualitative structured questionnaire of Australian and New Zealand clinical microbiology laboratories to document current blood culture practices and to determine whether expected quality standards are being met. Questions included a wide range of pre-analytical, analytical, and post-analytical aspects of blood cultures from adults. The responses from 71 laboratories were analysed. Compliance was high for use of a biological safety cabinet (90%), incubating for 5 days (86%), and commenting on likely contaminants (85%). While Gram stains were reported within 2 hours during normal hours (93%), reporting was slower after hours (59%), p<0.001. The volume of blood collected for a clinical episode was poorly monitored with only 11% (n=8) of laboratories regularly auditing the number of blood culture sets and 3% (n=2) monitoring adequacy of fill. Most laboratories received blood cultures from off-site with just 34% (n=21) meeting guidance for loading bottles onto the analyser within 4 hours. More laboratories met standards for loading bottles onto the analyser during working hours than after hours: 87% vs 56%, p<0.001. Most laboratories did not monitor the contamination rate, 56% (n=40), and only 27% (n=19) knew their rate was below the guidance threshold of less than -3%. Considerable opportunities exist to improve quality assurance of blood culture practice in Australia and New Zealand, especially for the most critical aspect affecting culture sensitivity, the volume of blood collected.

Clinical consequences of contaminated blood cultures in adult hospitalized patients at an institution utilizing a rapid blood-culture identification system

OBJECTIVE

To assess the clinical impact of contaminated blood cultures in hospitalized patients during a period when rapid diagnostic testing using a FilmArray Blood Culture Identification (BCID) panel was in use.

DESIGN

Retrospective cohort study.

SETTING

Single academic medical center.

PARTICIPANTS

Patients who had blood culture(s) performed during an admission between June 2014 and December 2016.

METHODS

Length of hospital stay and days of antibiotic therapy were assessed in relation to blood-culture contamination using generalized linear models with univariable and multivariable analyses.

RESULTS

Among 11,474 patients who had blood cultures performed, the adjusted mean length of hospital stay for patients with contaminated blood-culture episodes (N = 464) was 12.3 days (95% confidence interval [CI], 11.4-13.2) compared to 11.5 days (95% CI, 11.0-11.9) for patients (N = 11,010) with negative blood-culture episodes (P = .032). The adjusted mean durations of antibiotic therapy for patients with contaminated and negative blood-culture episodes were 6.0 days (95% CI, 5.3-6.7) and 5.2 days (95% CI, 4.9-5.4), respectively (P = .011).

CONCLUSIONS

Despite the use of molecular-based, rapid blood-culture identification, contamination of blood cultures continues to result in prolonged hospital stay and unnecessary antibiotic therapy in hospitalized patients.