Contaminants in blood cultures: importance, implications, interpretation and prevention

Reducing Blood Culture Contamination Rates: Introduction of a Combined Education and Skin Antisepsis Intervention

Background. Blood culture contamination (BCC) is an important quality concern in clinical microbiology as it can lead to unnecessary antimicrobial therapy in patients and increased workload for laboratory scientists. The Clinical Laboratory and Standards Institute recommend BCC rates to be <3 % and recently updated guidelines have set a new goal of 1 %. The aim of this project was to design and implement interventions to reduce BCC rates at our institution. Methods. We introduced a combined education and skin antisepsis intervention in a large Model 4 academic teaching hospital in the South of Ireland. BD ChloraPrep skin antisepsis applicators (2 % chlorhexidine gluconate/70 % isopropyl alcohol), licensed for use for blood culture specimen collection, were introduced, replacing Clinell (2 % chlorhexidine gluconate/70 % isopropyl alcohol) wipes. In addition, a multimodal education programme was designed and delivered. This consisted of a video demonstrating the recommended blood culture specimen collection technique using the new applicators as well as simulation training for all interns. The video was uploaded to the intranet as an educational resource available to all staff. Results. The interventions were implemented in July 2022 and BCC rates pre- and post-intervention were calculated. The average BCC rate for the 12 months preceding the intervention (July 2021 to July 2022) was 2.56 % with highest rates in the Emergency Department. This compared to an average rate of 2.2 % in the 12 months post-intervention (July 2022 to July 2023). In comparing the two rates the reduction in BCC rates between the two periods was not statistically significant (P=0.30). Conclusion. Overall BCC rates reduced but the difference between the two periods did not reach statistical significance. The resource-intensive nature of providing regular and timely feedback of contamination rates and the larger impact of in-person education and training over virtual modalities may explain the modest reduction. Further investments in these areas, particularly in the Emergency Department, will be necessary to further reduce rates in line with new recommendations.

Timing and prediction of secondary bacteremia in patients with COVID-19: A retrospective cohort study

Background

We aimed to aid the appropriate use of antimicrobial agents by determining the timing of secondary bacteremia and validating and updating clinical prediction models for bacteremia in patients with COVID-19.

Methods

We performed a retrospective cohort study on all hospitalized patients diagnosed with COVID-19 who underwent blood culture tests from January 1, 2020, and September 30, 2021, at an urban teaching hospital in Japan. The primary outcome measure was secondary bacteremia in patients with COVID-19.

Results

Of the 507 patients hospitalized with COVID-19, 169 underwent blood culture tests. Eleven of them had secondary bacteremia. The majority of secondary bacteremia occurred on or later than the 9th day after symptom onset. Positive blood culture samples collected on day 9 or later after disease onset had an odds ratio of 22.4 (95% CI 2.76-181.2, p < 0.001) compared with those collected less than 9 days after onset. The area under the receiver operating characteristic curve of the modified Shapiro rule combined with blood culture collection on or after the 9th day from onset was 0.919 (95% CI, 0.843-0.995), and the net benefit was high according to the decision curve analysis.

Conclusions

The timings of symptom onset and hospital admission may be valuable indicators for making a clinical decision to perform blood cultures in patients hospitalized with COVID-19.

Predictors of Invasive Bacterial Infection in Febrile Infants Aged 2 to 6 Months in the Emergency Department

Our goal was to identify predictors of invasive bacterial infection (ie, bacteremia and bacterial meningitis) in febrile infants aged 2-6 months. In our multicenter retrospective cohort, older age and lower temperature identified infants at low risk for invasive bacterial infection who could safely avoid routine testing.

It is time for a unified definition of native vertebral osteomyelitis: a framework proposal

In recent years, there has been a notable increase in research output on native vertebral osteomyelitis (NVO), coinciding with a rise in its incidence. However, clinical outcomes remain poor, due to frequent relapse and long-term sequelae. Additionally, the lack of a standardized definition and the use of various synonyms to describe this condition further complicate the clinical understanding and management of NVO. We propose a new framework to integrate the primary diagnostic tools at our disposal. These collectively fall into three main domains: clinical, radiological, and direct evidence. Moreover, they and can be divided into seven main categories: (a) clinical features, (b) inflammatory biomarkers, (c) imaging techniques, microbiologic evidence from (d) blood cultures and (e) invasive techniques, (f) histopathology, and (g) empirical evidence of improvement following the initiation of antimicrobial therapy. We provide a review on the evolution of these techniques, explaining why no single method is intrinsically sufficient to formulate an NVO diagnosis. Therefore, we argue for a consensus-driven, multi-domain approach to establish a comprehensive and universally accepted definition of NVO to enhance research comparability, reproducibility, and epidemiological tracking. Ongoing research effort is needed to refine these criteria further, emphasizing collaboration among experts through a Delphi method to achieve a standardized definition. This effort aims to streamline research, expedite accurate diagnoses, optimize diagnostic tools, and guide patient care effectively.

Ciprofloxacin prophylaxis during haematopoietic cell transplantation: a role for use in patients with germ cell tumours?

Introduction. Fluoroquinolone prophylaxis during haematopoietic cell transplantation (HCT) can lead to antimicrobial resistance (AMR). Identifying the groups of patients that have the highest likelihood of benefiting from prophylactic antimicrobials is important for antimicrobial stewardship (AMS).Hypothesis. We aimed to identify groups of HCT recipients that have the highest likelihood of benefiting from prophylactic fluroquinolones.Methods. All admissions for HCT in a tertiary centre between January 2020 and December 2022 (N = 400) were retrospectively studied. Allogeneic HCT (allo-HCT) recipients had prophylaxis with ciprofloxacin during the chemotherapy-induced neutropenia, while autologous HCT (auto-HCT) recipients did not. Bacteraemias were recorded when non-contaminant bacterial pathogens were isolated in blood cultures.Results. Allo-HCT was performed for 43.3 % (173/400) of patients and auto-HCT was performed for 56.7 % (227/400). A bacteraemia was documented in 28.3 % (113/400) of cases. Allo-HCT recipients were more likely to have a Gram-positive bacteraemia (20.8%, 36/173, vs 10.1%, 23/227, P = 0.03), while a difference was not observed for Gram-negative bacteraemias (18.5%, 32/173 vs 18.1%, 41/227, P = 0.91). Among auto-HCT recipients not receiving ciprofloxacin prophylaxis, patients with germ cell tumours had the highest probability (P for trend 0.09) of recording any bacteraemia (43.5%, 10/23) followed by patients with lymphomas (32.5%, 13/40), other auto-HCT indications (22.2%, 2/9), multiple myeloma (22.1%, 29/131) and multiple sclerosis (12.5%, 3/24). The higher number of bacteraemias in patients with germ cell tumours was primarily driven by Gram-negative pathogens.Conclusions. Ciprofloxacin prophylaxis was associated with a reduced incidence of Gram-negative bacteraemias in allo-HCT recipients. Auto-HCT recipients due to germ cell tumours, not receiving ciprofloxacin prophylaxis, recorded the highest incidence of bacteraemias and represent a possible target group for this intervention.

Consensus document of the Spanish Society of Paediatric Infectious Diseases (SEIP) and the Spanish Society of Paediatric Intensive Care (SECIP) for the diagnosis and treatment of central venous catheter-related infections in paediatric care

Intravascular devices are essential for the diagnostic and therapeutic approach to multiple diseases in paediatrics, and central venous catheters (CVCs) are especially important. One of the most frequent complications is the infection of these devices, which is associated with a high morbidity and mortality. These infections are highly complex, requiring the use of substantial resources, both for their diagnosis and treatment, and affect vulnerable paediatric patients admitted to high-complexity units more frequently. There is less evidence on their management in paediatric patients compared to adults, and no consensus documents on the subject have been published in Spain. The objective of this document, developed jointly by the Spanish Society of Paediatric Infectious Diseases (SEIP) and the Spanish Society of Paediatric Intensive Care (SECIP), is to provide consensus recommendations based on the greatest degree of evidence available to optimize the diagnosis and treatment of catheter-related bloodstream infections (CRBSIs). This document focuses on non-neonatal paediatric patients with CRBSIs and does not address the prevention of these infections.

Changing culture: An intervention to improve blood culture quality in the emergency department

OBJECTIVE

Blood cultures (BCs) remain a key investigation in ED patients at risk of bacteraemia. The aim of this study was to assess the effect of a multi-modal, nursing-led intervention to improve the quality of BCs in the ED, in terms of single culture, underfilling and contamination rates.

METHOD

The present study was conducted in the ED of a large urban tertiary referral hospital. The study included four phases: pre-intervention, intervention, post-intervention and sustainability periods. A multi-modal intervention to improve BC quality consisting small group education, posters, brief educational videos, social media presence, quality feedback, small group/individual mentoring and availability of BC collection kits was designed and delivered by two senior ED nurses over 7 weeks. Study data comprised rates of single, underfilled and contaminated cultures in each of three 18-week periods: pre-intervention (baseline), post-intervention and sustainability.

RESULTS

Over the study period 4908 BC sets were collected during 2347 episodes of care in the ED. Single culture sets reduced from 56.2% in the pre-intervention period to 22.8% post-intervention (P < 0.01) and 18.8% in the sustainability period (P < 0.01). Underfilled bottle rates were also significantly reduced (aerobic 52.8% pre-intervention to 19.2% post-intervention, 18.8% sustainability, anaerobic 46.8% pre-intervention to 23.3% post-intervention, 23.8% sustainability). Skin contaminants were grown from 3.7% of BC sets in the pre-intervention period, improving to 1.5% in the post-intervention period (P < 0.001) and 2.1% in the sustainability period (P = 0.03). Total volume of blood cultured was significantly associated with diagnosis of bacteraemia.

CONCLUSION

Significant improvements in BC quality are possible with nursing-based interventions in the ED.

Clinical impact of preservation fluid contamination on kidney transplant patients

BACKGROUND

Kidney transplantation is associated with a high risk of infectious complications due to immunosuppressive therapy. Although infections may be transmitted from donor to transplant recipient through contaminated preservation solution (PS), the clinical impact of this is not well-understood.

METHODS

We retrospectively evaluated PS contamination rates in a series of 339 patients who underwent cadaveric renal transplant at our centre. All patients with a positive culture received targeted preemptive therapy (PET).

RESULTS

Of the 339 PS samples, 136 (40.1%) were positive for a microorganism, mainly coagulase-negative staphylococci (CoNS; n = 89;60.5%), gram-negative bacilli (n = 31;21.1%), non-CoNS gram-positive cocci (n = 18;12.2%), and Candida spp (n = 2;1.4%). Of the 136 positive cases, 42 (30.9%) received PET (12.4% of the cohort). No cases of urinary tract infection, surgical site infection, or graft loss were observed. Overall, our findings indicate that PS contamination, mainly by saprophytic skin flora (CoNS) is common. Only 8% of patients required antibiotic or antifungal therapy.

CONCLUSION

The infection transmission rate from donors to recipients was negligible (0%), perhaps due to the early initiation of a targeted PET after isolation of a recognized pathogen. More data from large, prospective studies are needed to confirm these findings.

The effect of ciprofloxacin prophylaxis during haematopoietic cell transplantation on infection episodes, exposure to treatment antimicrobials and antimicrobial resistance: a single-centre retrospective cohort study

Objectives

Fluroquinolone prophylaxis during haematopoietic cell transplantation (HCT) remains contentious. We aimed to determine its effectiveness and association with exposure to treatment antimicrobials and antimicrobial resistance.

Methods

All admission episodes for HCT (N = 400 , 372 unique patients) in a tertiary centre between January 2020 and December 2022 were studied. Allogeneic HCT (allo-HCT) recipients received prophylaxis with ciprofloxacin during chemotherapy-induced neutropenia, while autologous HCT (auto-HCT) recipients did not.

Results

Allo-HCT was performed for 43.3% (173/400) of patients, auto-HCT for 56.7% (227/400). Allo-HCT was associated with an average of 1.01 fewer infection episodes per 100 admission days (95% CI 0.62-1.40, P < 0.001) compared with auto-HCT. In allo-HCT, the total exposure to all antimicrobials was higher [+24.8 days of therapy (DOT)/100 admission days, P < 0.001], as was exposure to ciprofloxacin (+40.5 DOT/100 admission days, P < 0.001). By contrast, exposure to meropenem (-4.5 DOT/100 admission days, P = 0.02), piperacillin/tazobactam (-5.2 DOT/100 admission days, P < 0.001), aminoglycosides (-4.5 DOT/100 admission days, P < 0.001) and glycopeptides (-6.4 DOT/100 admission days, P < 0.001) was reduced. Enterobacteriaceae isolated during allo-HCT were more resistant to ciprofloxacin (65.5%, 19/29 versus 6.1%, 2/33, P < 0001), ceftriaxone (65.5%, 19/29 versus 9.1%, 3/33, P < 0.001), other antimicrobial classes. Vancomycin-resistant enterococci were more common in allo-HCT recipients (11%, 19/173 versus 0.9%, 2/227, P < 0.001). Inpatient mortality during allo- and auto-HCT was 9.8% (17/173) and 0.4% (1/227). respectively (P < 0.001).

Conclusions

Ciprofloxacin prophylaxis in allo-HCT was associated with fewer infection episodes and reduced exposure to treatment antimicrobials. Mortality in auto-HCT remained low. A significant burden of antimicrobial resistance was detected in allo-HCT recipients.

A multi-pronged approach to improve blood culture diagnostics in different clinical departments: a single-centre experience

PURPOSE

Blood culture (BC) diagnostics are influenced by many factors. We performed a targeted interdisciplinary analysis to analyse effects of various measures on BC diagnostics performance.

METHODS

A diagnostic stewardship initiative was conducted at two intervention and two control wards in a German tertiary level hospital. The initiative comprised staff training on the correct indications and sampling for BC, implementation of information cards, labels to identify the collection site, regular BC bottle feedback including the number of bottles, filling volumes and identified pathogens; and the use of a specific sampling device (BD Vacutainer®). Before and after the interventions, two three-month measurement periods were performed, as well as a one-month follow-up period to assess the sustainability of the conducted measures.

RESULTS

In total, 9362 BC bottles from 787 patients were included in the analysis. The number of BCs obtained from peripheral venous puncture could be increased at both intervention wards (44.0 vs. 22.2%, 58.3 vs. 34.4%), while arterial sampling could be reduced (30.6 vs. 4.9%). A total of 134 staff members were fully trained. The intervention led to a considerable increase in BC knowledge (from 62.4 to 79.8% correct answers) with differences between the individual professional groups. Relevant reduced contamination rates could be detected at both intervention wards.

CONCLUSIONS

As knowledge on the correct BC sampling and strategies to reduce contamination varies considerably between clinical departments and healthcare professionals, a targeted training should be adapted to the specific needs of the individual professional groups. An additional filling device is not necessary.

Effect of an initial specimen diversion device on blood-culture contamination rates and vancomycin usage: A quasi-experimental study

Initial specimen diversion devices (ISDDs) are a potential solution for reducing blood-culture contamination rates. We report the implementation of an ISDD associated with a sustained reduction in blood-culture contamination rates for >18 months after implementation. We did not observe a clinically significant reduction in inpatient vancomycin usage.

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.

Assessment of the impact of centralized bioMérieux BACT/ALERT® VIRTUO® blood culture system (VIRTUO) implementation on outcomes in patients with gram-negative bacteremia

BACKGROUND

We evaluated pre- and postimplementation of Virtuo on outcome in patients with gram-negative bacteremia using a quasiexperimental time-in-motion design.

METHODS

Becton Dickinson BACTEC™ 9000 series (Bactec) (2018) and Virtuo system (2020) were utilized in a decentralized and centralized process, respectively. Data collected in August-December in 2018 and 2020 were analyzed with SPSS (ver 28).

RESULTS

For 185 patients in each time period, patient age, gender, length of hospitalization were not different. However, blood culture (BC) volume was significantly lower in 2020 (7.1 ± 2.6 mL) compared to 2018 (8.9 ± 1.9 mL). Time from BC draw and time from pathogen identification (ID) to treatment change were both significantly faster in 2020 (52.9 ± 38.3 hours; 15.1 ± 27.4 hours), compared to 2018 (65.0 ± 46.3 hours; 23.8 ± 33.8), respectively.

CONCLUSIONS

Replacement of decentralized Bactec with centralized Virtuo, resulted in significant improvement in management of patients gram-negative bacteremia.

Are bacteria, fungi, and archaea present in the midtrimester amniotic fluid?

OBJECTIVES

This study was conducted to determine whether bacteria, fungi, or archaea are detected in the amniotic fluid of patients who underwent midtrimester amniocentesis for clinical indications.

METHODS

Amniotic fluid samples from 692 pregnancies were tested by using a combination of culture and end-point polymerase chain reaction (PCR) techniques. Intra-amniotic inflammation was defined as an interleukin-6 concentration >2,935 pg/mL.

RESULTS

Microorganisms were detected in 0.3% (2/692) of cases based on cultivation, 1.73% (12/692) based on broad-range end-point PCR, and 2% (14/692) based on the combination of both methods. However, most (13/14) of these cases did not have evidence of intra-amniotic inflammation and delivered at term. Therefore, a positive culture or end-point PCR in most patients appears to have no apparent clinical significance.

CONCLUSIONS

Amniotic fluid in the midtrimester of pregnancy generally does not contain bacteria, fungi, or archaea. Interpretation of amniotic fluid culture and molecular microbiologic results is aided by the assessment of the inflammatory state of the amniotic cavity. The presence of microorganisms, as determined by culture or a microbial signal in the absence of intra-amniotic inflammation, appears to be a benign condition.

Impact of the COVID-19 Pandemic on the Epidemiology of Bloodstream Infections in Hospitalized Patients-Experience from a 4th Military Clinical Hospital in Poland

Bloodstream infections (BSIs) are associated with high mortality and inappropriate or delayed antimicrobial therapy. The purpose of this study was to investigate the impact of the COVID-19 pandemic on the epidemiology of BSIs in hospitalized patients. The research aimed to compare the incidence of BSIs and blood culture results in patients hospitalized before and during the COVID-19 pandemic.

METHODS

Retrospective and prospective data were collected from blood cultures obtained from 4289 patients hospitalized between June 2018 and July 2022. Two groups of patients were distinguished: those with BSIs admitted during the pre-COVID-19 period and those admitted during the COVID-19 surge. Demographic and clinical data, blood cytology, and biochemistry results were analyzed, and the usefulness of PCT was assessed in patients with COVID-19.

RESULTS

The study showed a significant increase in the incidence of BSIs during the pandemic compared to the pre-COVID-19 period. Positive blood cultures were obtained in 20% of patients hospitalized during the pandemic (vs. 16% in the pre-COVID-19 period). The incidence of BSIs increased from 1.13 to 2.05 cases per 1000 patient days during COVID-19, and blood culture contamination was more frequently observed. The mortality rate was higher for patients hospitalized during the COVID-19 pandemic. An increased frequency of MDRO isolation was observed in the COVID-19 period.

CONCLUSIONS

The incidence of BSIs increased and the mortality rate was higher in the COVID-19 period compared to the pre-COVID-19 period. The study showed limited usefulness of procalcitonin in patients with COVID-19, likely due to the administered immunosuppressive therapy.

Diagnostic Stewardship: A Systematic Review and Meta-analysis of Blood Collection Diversion Devices Used to Reduce Blood Culture Contamination and Improve the Accuracy of Diagnosis in Clinical Settings

Background

Blood culture contamination may lead to misdiagnosis, overutilization of antibiotics, and prolonged length of stay. Blood specimen diversion devices can reduce contamination rates during blood culture collection procedures. We performed a systematic literature review and meta-analysis evaluating the influence of blood specimen diversion devices in blood culture contamination rates.

Methods

We searched Medline, Cumulative Index to Nursing and Allied Health Literature, Embase, Cochrane, Scopus, and Web of Science, from database inception to 1 March 2023, for studies evaluating the impact of a diversion device on blood culture contamination. Blood culture contamination was a positive blood culture with microorganisms not representative of true bacteremia, but rather introduced during collection or processing the blood sample. Random-effects models were used to obtain pooled mean differences, and heterogeneity was assessed using the I2 test.

Results

Of 1768 screened studies, 12 met inclusion criteria for this systematic literature review. Of them, 9 studies were included in the meta-analysis. Studies were substantially heterogeneous, but stratified analyses considering only high-quality studies revealed that venipuncture using a diversion device was associated with a significant reduction in blood culture contamination in comparison to the standard procedure of collection (pooled odds ratio [OR], 0.26 [95% confidence interval {CI}, .13-.54]; I2 = 19%). Furthermore, the stratified analysis showed that the adoption of a diversion device did not reduce the detection of true infection (pooled OR, 0.85 [95% CI, .65-1.11]; I2 = 0%).

Conclusions

Blood culture diversion devices was associated with decreased contamination rates and could improve quality of care, reduce costs, and avoid unnecessary antibiotic use.

Use and Quality of Blood Cultures for the Diagnosis of Bloodstream Infections: A Cross-Sectional Study in the Ho Teaching Hospital, Ghana, 2019-2021

Blood Culture and Drug Susceptibility Testing (CDST) remains vital for the diagnosis and management of bloodstream infections (BSIs). While the Ghana National Standard Treatment Guidelines require CDST to be performed in each case of suspected or clinically diagnosed BSI, these are poorly adhered to in the Ho Teaching Hospital (HTH). This study used secondary medical and laboratory records to describe blood CDST requests by clinicians and the quality of CDST processes for the diagnosis of BSI among patients admitted to HTH from 2019 to 2021. Of 4278 patients, 33% were infants. Pneumonia and neonatal sepsis cases were 40% and 22%, respectively. Only 8% (351/4278) had blood CDST requested. Of 94% (329/351) blood CDST processed and reported, only 7% (22/329) were culture-positive, with likely contaminants being recovered from 16% (52/329) of the specimens. The duration from admission to request was 2 days (IQR: 0-5), and Further qualitative studies must be conducted to understand the reasons for low blood CDST utilisation among clinicians and the patient outcomes. Targeted interventions are required to enhance the utilisation of blood CDST by clinicians and the quality of laboratory processes.

Blood culture contamination in a tertiary care hospital: a retrospective three-year study

BACKGROUND

Bloodstream infections (BSI) are a leading cause of morbidity and mortality in hospitalized patients worldwide. A blood culture is the primary tool for determining whether a patient has BSI and requires antimicrobial therapy, but it can result in an inappropriate outcome if the isolated microorganisms are deemed contaminants from the skin. Despite the development of medical equipment and technology, there is still a percentage of blood culture contamination. The aims of this study were to detect the blood culture contamination (BCC) rate in a tertiary care hospital in Palestine and to identify the departments with the highest rates along with the microorganisms isolated from the contaminated blood samples.

METHOD

Blood cultures that were taken at An-Najah National University Hospital between January 2019 and December 2021 were evaluated retrospectively. Positive blood cultures were classified as either true positives or false positives based on laboratory results and clinical pictures. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) version 21. A p-value of less than 0.05 was considered statistically significant for all analyses.

RESULTS

Out of 10,930 blood cultures performed in the microbiology laboratory from 2019 to 2021, 1479 (13.6%) were identified as positive blood cultures that showed microbial growth. Of these, 453 were blood culture contaminations, representing 4.17% of total blood cultures and 30.63% of the positive blood culture samples. The highest rate of contamination was in the hemodialysis unit (26.49%), followed by the emergency department (15.89%). Staphylococcus epidermidis was the most prevalent (49.2%), followed by Staphylococcus hominis (20.8%) and Staphylococcus haemolyticus (13.2%). The highest annual contamination rate was observed in 2019 (4.78%) followed by 2020 (3.95%) and the lowest was in 2021 (3.79%). The rate of BCC was decreasing, although it did not reach statistically significant levels (P value = 0.085).

CONCLUSION

The rate of BCC is higher than recommended. The rates of BCC are different in different wards and over time. Continuous monitoring and performance improvement projects are needed to minimize blood culture contamination and unnecessary antibiotic use.

Staphylococcus aureus and Coagulase-Negative Staphylococci from Bloodstream Infections: Frequency of Occurrence and Antimicrobial Resistance, 2018-2021

BACKGROUND

The abuse of antibiotics during the SARS-CoV-2 pandemic might have disrupted efforts to curb the further development and spread of the antimicrobial resistance of Staphylococcus aureus infection and Staphylococcus spp. coagulase-negative (CoNS) agents of nosocomial bloodstream infections (NBSIs). The purpose of our work was to study the resistance patterns of Staphylococcus aureus and CoNS through the analysis of blood cultures in hospitalized SARS-CoV-2-positive and SARS-CoV-2-negative patients (pts.).

MATERIALS AND METHODS

During the period January 2018-June 2021, a retrospective case-control study was performed on blood cultures positive for Staphylococcus spp. detected in 177 adult pts. (≥18 years old) hospitalized for >48 hours at Sant'Elia Hospital, Caltanissetta.

RESULTS

Staphylococcus aureus was isolated in 33.9% of blood culture samples, and among CoNS, the most frequent strains were Staphylococcus capitis (18.6%) and Staphylococcus hominis (18.1%). Patients aged ≥ 65 years, with a greater number of males, comprised the SARS-CoV-2-negative pts. (71.8% vs. 52.2%, p = 0.0154). Among the SARS-CoV-2-positive patients, the significant resistance of Staphylococcus aureus was only observed for erythromycin (57.1%). The oxacillin resistance of Staphylococcus capitis was higher in SARS-CoV-2-positive than in negative pts. (90% and 78.3%, respectively). Comparing the two groups, we found an increase in resistance in SARS-CoV-2-negative patients for the following antibiotics: gentamicin for Staphylococcus aureus (p = 0.007), clindamycin and erythromycin (p = 0.012) for Staphylococcus hominis and oxacillin and rifampicin for Staphylococcus haemoliticus (p = 0.012).

CONCLUSIONS

Our study confirms the relevance of oxacillin-resistant Staphylococcus aureus in being responsible for bloodstream infection and draws attention to highly oxacillin-resistant CoNS such as Staphylococcus capitis. The presence of resistant strains of CoNS in hospitals can be worrying, as it limits treatment options and worsens outcomes. The Infection Control Committee (ICC) recommends new treatment strategies to decrease colonization and infections. As part of the implementation of a bloodstream infection prevention program, the authors encourage the introduction of a report on the antimicrobial resistance of hospital bacteremia due to CoNS.

Improving Blood Culture Quality with a Medical Staff Educational Program: A Prospective Cohort Study

Purpose

Blood cultures (BCs) are essential laboratory tests for diagnosing blood stream infections. BC diagnostic improvement depends on several factors during the preanalytical phase outside of innovative technologies. In order to evaluate the impact of an educational program on BC quality improvement, a total of 11 hospitals across China were included from June 1st 2020 to January 31st 2021.

Methods

Each hospital recruited 3 to 4 wards to participate. The project was divided into three different periods, pre-implementation (baseline), implementation (educational activities administered to the medical staff) and post-implementation (experimental group). The educational program was led by hospital microbiologists and included professional presentations, morning meetings, academic salons, seminars, posters and procedural feedback.

Results

The total number of valid BC case report forms was 6299, including 2739 sets during the pre-implementation period and 3560 sets during the post-implementation period. Compared with the pre-implementation period, some indicators, such as the proportion of patients who had 2 sets or more, volume of blood cultured, and BC sets per 1000 patient days, were improved in the post-implementation period (61.2% vs 49.8%, 18.56 vs 16.09 sets, and 8.0 vs 9.0mL). While BC positivity and contamination rates did not change following the educational intervention (10.44% vs 11.97%, 1.86% vs 1.94%, respectively), the proportion of coagulase negative staphylococci-positive samples decreased in BSI patients (6.87% vs 4.28%).

Conclusion

Therefore, medical staff education can improve BC quality, especially increasing volume of blood cultured as the most important variable to determine BC positivity, which may lead to improved BSI diagnosis.

Pathology stewardship in emergency departments: a single-site, retrospective, cohort study of the value of C-reactive protein in patients with suspected sepsis

Increasing awareness of the importance of pathology stewardship in reducing low value care has led to scrutiny of appropriate laboratory test ordering. The objective of this study is to investigate the value of a commonly ordered laboratory test, the C-reactive protein (CRP), in decisions regarding diagnosis, management and disposition of emergency department (ED) patients with suspected sepsis. Retrospective chart reviews were performed on 1716 adult patients with suspected sepsis presenting to the Townsville University Hospital ED between 1 January 2021 and 30 June 2021. Suspected sepsis was defined as the emergency clinicians' decision to perform a blood culture. A CRP value of 10 mg/L or higher was defined as an elevated CRP. The primary outcome of interest was commencement of antibiotics in ED. Secondary outcomes include hospital admission (ward and ICU), hospital length of stay, mortality, documentation of indication for CRP testing, test parameters of CRP in detecting culture-positive bacteraemia and rates of bacteraemia with presumptive ED diagnosis. This study found no significant association between CRP values and antibiotic commencement (p=0.222), ward admission (p=0.071), ICU admission (p=0.248), hospital length of stay (p=0.164) or mortality (p=1.000). CRP had an area under the curve of 0.58 (95% CI 0.51-0.66) for detecting culture-positive bacteraemia. Sensitivity and specificity of CRP were 62.5% and 47.7%, respectively, at a threshold of 46 mg/dL. CRP testing is of little value in ED patients with suspected sepsis as it does not influence decision making about diagnosis, management, or disposition. Avoiding CRP testing in this patient cohort can contribute to pathology stewardship and optimal use of finite healthcare resources.

Challenging the Hypothesis of in Utero Microbiota Acquisition in Healthy Canine and Feline Pregnancies at Term: Preliminary Data

At present, there are no data on the presence of bacteria in healthy canine and feline pregnancies at term. Here, we investigated the uterine microbiome in bitches (n = 5) and queens (n = 3) undergoing elective cesarean section in two facilities. Samples included swabs from the endometrium, amniotic fluid, and meconium, and environmental swabs of the surgical tray as controls. Culture and 16S rRNA gene sequencing were used to investigate the presence of bacteria. Culture was positive for 34.3% of samples (uterus n = 3, amniotic fluid n = 2, meconium n = 4, controls n = 0), mostly with low growth of common contaminant bacteria. With sequencing techniques, the bacterial abundance was significantly lower than in environmental controls (p < 0.05). Sequencing results showed a species-specific pattern, and significant differences between canine and feline bacterial populations were found at order, family, and genus level. No differences were found in alpha and beta diversities between feto-maternal tissues and controls (p > 0.05). Dominant phyla were Bacteroidetes, Firmicutes, and Proteobacteria in different proportions based on tissue and species. Culture and sequencing results suggest that the bacterial biomass is very low in healthy canine and feline pregnancies at term, that bacteria likely originate from contamination from the dam's skin, and that the presence of viable bacteria could not be confirmed most of the time.

Genetic Diseases and Invasive Infections in Infants 100 Days or Younger

BACKGROUND

Understanding the association of genetic diseases with invasive infections in neonates or infants is important, given the clinical and public health implications of genetic diseases.

METHODS

We conducted a retrospective case-control study over a 5-year period to investigate the association between genetic diseases and invasive infections in neonates or infants. The case group included 56 patients with laboratory-confirmed invasive infections and a genetic etiology identified by exome sequencing. Another 155 patients without a genetic etiology were selected as controls from the same pool of patients.

RESULTS

An overview of genetic diseases that predispose patients to develop invasive infections were outlined. We identified 7 independent predictors for genetic conditions, including prenatal findings [adjusted odds ratio (aOR), 38.44; 95% confidence interval (CI): 3.94-374.92], neonatal intensive care unit admission (aOR, 46.87; 95% CI: 6.30-348.93), invasive ventilation (aOR, 6.66; 95% CI: 3.07-14.46), bacterial infections (aOR, 0.21; 95% CI: 0.06-0.69), fever (aOR, 0.15; 95% CI: 0.08-0.30), anemia (aOR, 6.64; 95% CI: 3.02-14.59) and neutrophilia (aOR, 0.98; 95% CI: 0.96-0.99). The area under the curve for the predictive model was 0.921 (95% CI: 0.876-0.954). We also found that a genetic etiology [hazard ratio (HR), 7.25; 95% CI: 1.71-30.81], neurological manifestations (HR, 3.56; 95% CI: 1.29-9.88) and septic shock (HR, 13.83; 95% CI: 3.18-60.10) were associated with severe outcomes.

CONCLUSIONS

Our study established predictive variables and risk factors for an underlying genetic etiology and its mortality in neonates or infants with invasive infections. These findings could lead to risk-directed screening and treatment strategies, which may improve patient outcomes.

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.

An open-access laboratory medicine course for medical students

The senior author created a 2-week online laboratory medicine course for fourth-year medical students to meet an unmet need at our institution for a brief survey course of clinical pathology in an online format. The course includes online videos, reading assignments, study questions, and a rubric for written assignments that apply the key principles to topics that are customized based on the specialty interests of each student. Anonymous course evaluation surveys were completed by 42 of 60 students (70%), and 92% of respondents stated that they strongly agree with the quality metrics statements in the survey. The complete course materials are shared in this article in the spirit of open access and may be used for medical students, pathology residents, and other learners.

Assessment of a novel continuous cleaning device using metatranscriptomics in diverse hospital environments

Introduction

Despite routine implementation of cleaning and disinfection practices in clinical healthcare settings, high-touch environmental surfaces and contaminated equipment often serve as reservoirs for the transmission of pathogens associated with healthcare-associated infections (HAIs).

Methods

The current study involved the analysis of high-touch surface swabs using a metatranscriptomic sequencing workflow (CSI-Dx™) to assess the efficacy of cleanSURFACES® technology in decreasing microbial burden by limiting re-contamination. This is a non-human single center study conducted in the Emergency Department (ED) and on an inpatient Oncology Ward of Walter Reed National Military Medical Center that have followed hygienic practices during the COVID-19 pandemic environment.

Results

Although there was no difference in observed microbial richness (two-tailed Wilcoxon test with Holm correction, P > 0.05), beta diversity findings identified shifts in microbial community structure between surfaces from baseline and post-intervention timepoints (Day 1, Day 7, Day 14, and Day 28). Biomarker and regression analyses identified significant reductions in annotated transcripts for various clinically relevant microorganisms' post-intervention, coagulase-negative staphylococci and Malassezia restricta, at ED and Oncology ward, respectively. Additionally, post-intervention samples predominantly consisted of Proteobacteria and to a lesser extent skin commensals and endogenous environmental microorganisms in both departments.

Discussion

Findings support the value of cleanSURFACES®, when coupled with routine disinfection practices, to effectively impact on the composition of active microbial communities found on high-touch surfaces in two different patient care areas of the hospital (one outpatient and one inpatient) with unique demands and patient-centered practices.

Stenotrophomonas maltophilia Bacteremia: From Diagnosis to Treatment

Objective

There are many difficulties in diagnosing and treating Stenotrophomonas maltophilia bacteremia. In this study, we aimed to evaluate "true" and "false-positive bacteremia" and assess mortality risk factors and the impact of different treatment regimens.

Materials and Methods

Hospitalized adult patients with S. maltophilia-positive blood cultures were assessed by a two-stage analysis. First, the clinical significance of blood cultures was assessed, and patients were divided into "true" and "false-positive bacteremia" groups. Then, excluding false positives, we analyzed the antimicrobial regimens and the factors associated with 28-day mortality in true bacteremia cases performing univariate and multivariate analyses.

Results

The study included 127 out of 138 patients with S. maltophilia bacteremia. True bacteremia was identified in 51.2% and false-positive bacteremia in 48.8% of patients. In the true bacteremia group, hypotension, nosocomial bacteremia, concomitant infections, a source of bacteremia, two positive blood culture sets, and 28-day mortality were more common. The 28-day mortality was 50.7% among true bacteremia cases. In multivariate analysis, age and solid tumor were the independent predictors of 28-day mortality. Early effective antimicrobial therapy and different antimicrobial regimens, including trimethoprim-sulfamethoxazole (SXT), fluoroquinolones (FQs), and tigecycline (TGC), did not have any significant impact on survival.

Conclusion

Patients with S. maltophilia bacteremia should first be assessed regarding clinical significance. Clinical findings, the presence of multiple positive blood culture sets and the primary sources of bacteremia are useful parameters while discriminating true from false-positive bacteremia. Patients with advanced age and solid tumors should be followed carefully in terms of mortality. Antimicrobial regimens, including SXT, FQs, or TGC, can be preferred in patients with S. maltophilia bacteremia considering antimicrobial resistance and adverse effects or toxicity.

Effective Rapid Diagnosis of Bacterial and Fungal Bloodstream Infections by T2 Magnetic Resonance Technology in the Pediatric Population

Children are prone to bloodstream infections (BSIs), the rapid and accurate diagnosis of which is an unmet clinical need. The T2MR technology is a direct molecular assay for identification of BSI pathogens, which can help to overcome the limits of blood culture (BC) such as diagnostic accuracy, blood volumes required, and turnaround time. We analyzed results obtained with the T2Bacteria (648) and T2Candida (106) panels in pediatric patients of the Bambino Gesù Children's Hospital between May 2018 and September 2020 in order to evaluate the performance of the T2Dx instrument with respect to BC. T2Bacteria and T2Candida panels showed 84.2% and 100% sensitivity with 85.9% and 94.1% specificity, respectively. The sensitivity and specificity of the T2Bacteria panel increased to 94.9% and 98.7%, respectively, when BC was negative but other laboratory data supported the molecular result. T2Bacteria sensitivity was 100% with blood volumes <2 mL in neonates and infants. T2Bacteria and T2Candida provided definitive microorganism identification in a mean time of 4.4 and 3.7 h, respectively, versus 65.7 and 125.5 h for BCs (P < 0.001). T2 panels rapidly and accurately enable a diagnosis of a pediatric BSI, even in children under 1 year of age and for very small blood volumes. These findings support their clinical use in life-threatening pediatric infections, where the time to diagnosis is of utmost importance, in order to improve survival and minimize the long-term sequalae of sepsis. The T2 technology could be further developed to include more bacteria and fungi species that are involved in the etiology of sepsis.

Comparative of clinical performance between next-generation sequencing and standard blood culture diagnostic method in patients suffering from sepsis

BACKGROUND

Next-generation sequencing (NGS) is a massively unbiased sequencing technology. The objective of this study was to evaluate the performance of NGS-based approach in the detection of microorganisms from septic patients and compare with results of blood culture (BC).

METHODS

The observational and non-interventional study was conducted from April 2019 to August 2019.

RESULTS

A total of 96 sets of BC and 48 NGS results obtained from 48 septic patients were analyzed in this study. Thirty-two microorganisms (27 bacteria, 3 fungi and 2 viral) were detected by NGS in 23 (47.9%) patients; and 18 bacteria in 18 (37.5%) patients by BC. Exclusion of skin commensals, the positivity of NGS and BC was 62.5% and 14.5%, respectively (P < 0.001). Microorganisms identified by NGS demonstrated positive agreement with BC in 12 (25%) patients, including concordant results in 11 (22.9%) cases, and discrepancy results in 1 (2%). Of 11 patients with concordant results, 4 had additional microorganisms detected by NGS. NGS-positive but BC-negative was found in 9 (18.7%) patients. Using NGS, difficult-to-culture micro-organisms such as Pneumocystic jirovecii was identified in 2 patients, and Leptospira interrogans in one. Six (12.5%) patients with BC-positive but NGS-negative, whereas skin commensals were isolated in 4 (66.6%) cases. The number of patients that were positive by BC only increase from 29% to 47.9% when combining NGS and BC analyses (P = 0.033).

CONCLUSIONS

Our study support the advantage of NGS for the diagnosis of infecting microorganisms in sepsis, especially for microorganisms that are currently difficult or impossible to culture.

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.

Bacterial coinfection and antimicrobial use among patients with COVID-19 infection in a referral center in the Philippines: A retrospective cohort study

•

The rate of COVID-19 and community-acquired coinfections was low.

•

Those who are coinfected have higher mortality, and need to be identified early.

•

Antibiotic use was disproportionately high and varied little over time.

•

Blood cultures are low yield, and should not be performed routinely.

Objective

This study aimed to describe community-acquired bacterial coinfection (CAI) and antimicrobial use among COVID-19 patients.

Methods

Electronic records were retrospectively reviewed, and clinical data, laboratory data, antibiotic use, and outcomes of patients with and without CAI were compared.

Results

Of 1116 patients, 55.1% received antibiotics within 48 hours, but only 66 (5.9%) had documented CAI, mainly respiratory (40/66, 60.6%). Patients with CAI were more likely to present with myalgia (p = 0.02), nausea/vomiting (p = 0.014), altered sensorium (p = 0.007), have a qSOFA ≥ 2 (p = 0.016), or require vasopressor support (p < 0.0001). Patients with CAI also had higher median WBC count (10 vs 7.6 cells/mm³), and higher levels of procalcitonin (0.55 vs 0.13, p = 0.0003) and ferritin (872 vs 550, p = 0.028). Blood cultures were drawn for almost half of the patients (519, 46.5%) but were positive in only a few cases (30/519, 5.8%). Prescribing frequency was highest at the start and declined only slightly over time. The mortality of those with CAI (48.5%) was higher compared with those without CAI (14.3%).

Conclusion

Overall CAI rate was low (5.9%) and antimicrobial use disproportionately high (55.0%), varying little over time. The mortality rate of coinfected patients was high. Certain parameters can be used to better identify those with CAI and those who need blood cultures.

Diagnostic stewardship for blood cultures in the emergency department: A multicenter validation and prospective evaluation of a machine learning prediction tool

Background

Overuse of blood cultures (BCs) in emergency departments (EDs) leads to low yields and high numbers of contaminated cultures, accompanied by increased diagnostics, antibiotic usage, prolonged hospitalization, and mortality. We aimed to simplify and validate a recently developed machine learning model to help safely withhold BC testing in low-risk patients.

Methods

We extracted data from the electronic health records (EHR) for 44.123 unique ED visits with BC sampling in the Amsterdam UMC (locations VUMC and AMC; the Netherlands), Zaans Medical Center (ZMC; the Netherlands), and Beth Israel Deaconess Medical Center (BIDMC; United States) in periods between 2011 and 2021. We trained a machine learning model on the VUMC data to predict blood culture outcomes and validated it in the AMC, ZMC, and BIDMC with subsequent real-time prospective evaluation in the VUMC.

Findings

The model had an Area Under the Receiver Operating Characteristics curve (AUROC) of 0.81 (95%-CI = 0.78–0.83) in the VUMC test set. The most important predictors were temperature, creatinine, and C-reactive protein. The AUROCs in the validation cohorts were 0.80 (AMC; 0.78–0.82), 0.76 (ZMC; 0.74–0.78), and 0.75 (BIDMC; 0.74–0.76). During real-time prospective evaluation in the EHR of the VUMC, it reached an AUROC of 0.76 (0.71–0.81) among 590 patients with BC draws in the ED. The prospective evaluation showed that the model can be used to safely withhold blood culture analyses in at least 30% of patients in the ED.

Interpretation

We developed a machine learning model to predict blood culture outcomes in the ED, which retained its performance during external validation and real-time prospective evaluation. Our model can identify patients at low risk of having a positive blood culture. Using the model in practice can significantly reduce the number of blood culture analyses and thus avoid the hidden costs of false-positive culture results.

Funding

This research project was funded by the Amsterdam Public Health – Quality of Care program and the Dutch “Doen of Laten” project (project number: 839205002).

Effects of Blood Culture Aerobic/Anaerobic Bottle Collection Patterns from Both Sides of the Body on Positive Blood Culture Rate and Time-to-Positivity

Background

Although the principles for blood cultures (BCs) guidelines provide a recommendation for collection patterns, the complexity of clinical practice occasionally prompts clinicians to adopt non-standard collection patterns. Here, we investigate the influences of different BC collection patterns on detection of pathogens.

Methods

The BC collection patterns of 96 hospitals were surveyed online. And a retrospective study of BC data from a tertiary hospital was conducted.

Results

The results showed that 53.1% of hospitals adopted the recommended patterns. Among the 1439 episodes of true-positive BCs, 67.4% were found in both the left- and right-sided bottles; 58.2% were found in both aerobic and anaerobic bottles.

Conclusion

The present study suggested that the rate of standard collection patterns of blood culture was low and the non-standard collection patterns were associated with decreased detection of pathogens. Simultaneous collection of blood on the left and right sides was recommended as an effective pattern of BC collection.

Clinical Characteristics Associated with Bacterial Bloodstream Coinfection in COVID-19

INTRODUCTION

Inappropriate antibiotic use in COVID-19 is often due to treatment of presumed bacterial coinfection. Predictive factors to distinguish COVID-19 from COVID-19 with bacterial coinfection or bloodstream infection are limited.

METHODS

We conducted a retrospective cohort study of 595 COVID-19 patients admitted between March 8, 2020, and April 4, 2020, to describe factors associated with a bacterial bloodstream coinfection (BSI). The primary outcome was any characteristic associated with BSI in COVID-19, with secondary outcomes including 30-day mortality and days of antibiotic therapy (DOT) by antibiotic consumption (DOT/1000 patient-days). Variables of interest were compared between true BSI (n = 25) and all other COVID-19 cases (n = 570). A secondary comparison was performed between positive blood cultures with true BSI (n = 25) and contaminants (n = 33) on antibiotic use.

RESULTS

Fever (> 38 °C) (as a COVID-19 symptom) was not different between true BSI (n = 25) and all other COVID-19 patients (n = 570) (p = 0.93), although it was different as a reason for emergency department (ED) admission (p = 0.01). Neurological symptoms (ED reason or COVID-19 symptom) were significantly higher in the true BSI group (p < 0.01, p < 0.01) and were independently associated with true BSI (ED reason: OR = 3.27, p < 0.01; COVID-19 symptom: OR = 2.69, p = 0.03) on multivariate logistic regression. High (15-19.9 × 109/L) white blood cell (WBC) count at admission was also higher in the true BSI group (p < 0.01) and was independently associated with true BSI (OR = 2.56, p = 0.06) though was not statistically significant. Thirty-day mortality was higher among true BSI (p < 0.01). Antibiotic consumption (DOT/1000 patient-days) between true BSI and contaminants was not different (p = 0.34). True bloodstream coinfection was 4.2% (25/595) over the 28-day period.

CONCLUSION

True BSI in COVID-19 was associated with neurological symptoms and nonsignificant higher WBC, and led to overall higher 30-day mortality and worse patient outcomes.

Effects of COVID-19 on Blood Culture Contamination at a Tertiary Care Academic Medical Center

The COVID-19 pandemic has changed health care, from increased needs of personal protective equipment (PPE) to overloaded staff and influxes of patients. Blood cultures are frequently used to detect bloodstream infections in critically ill patients, but it is unknown whether the COVID-19 pandemic has had an impact on blood culture contamination rates. A total of 88,332 blood cultures taken over a 33-month period were analyzed to compare blood culture contamination rates before the COVID-19 pandemic to rates during the pandemic. A significant increase in the average number of monthly nurse-drawn and peripherally collected cultures occurred after the start of the pandemic, but there was a decrease in the average number of phlebotomy cultures. A significant increase in contamination rates (P < 0.001) was found in all nonemergency hospital departments during the COVID-19 pandemic, increasing from 2.1% to 2.5%. Increased rates during the COVID-19 pandemic were also found for nursing staff (2.0% to 2.4%) and both peripheral (2.1% to 2.5%) and indwelling line draws (1.1% to 1.7). The number of cultures drawn monthly increased in acute adult departments and both adult and pediatric emergency departments. Blood culture contamination rates in adult acute, adult emergency, and pediatric intensive care units increased after the start of the pandemic by 23%, 75%, and 59%, respectively. A positive correlation was found between blood culture contamination rates and COVID-19 incidence rates. Additional periodic staff training on proper blood collection technique and awareness of the workload of health care workers are recommended to decrease contamination rates during the COVID-19 pandemic. IMPORTANCE Understanding factors that contribute to blood culture contamination is important in order to take steps to limit contamination events. Here, we examine the effect the COVID-19 pandemic has had on blood culture contamination rates and specifically detail the effects based on the staff, draw types, and unit types. The conclusions provided here can be used as hospitals and laboratories navigate the COVID-19 pandemic or other times of high patient volume.

Molecular Methodologies for Improved Polymicrobial Sepsis Diagnosis

Polymicrobial sepsis is associated with worse patient outcomes than monomicrobial sepsis. Routinely used culture-dependent microbiological diagnostic techniques have low sensitivity, often leading to missed identification of all causative organisms. To overcome these limitations, culture-independent methods incorporating advanced molecular technologies have recently been explored. However, contamination, assay inhibition and interference from host DNA are issues that must be addressed before these methods can be relied on for routine clinical use. While the host component of the complex sepsis host–pathogen interplay is well described, less is known about the pathogen’s role, including pathogen–pathogen interactions in polymicrobial sepsis. This review highlights the clinical significance of polymicrobial sepsis and addresses how promising alternative molecular microbiology methods can be improved to detect polymicrobial infections. It also discusses how the application of shotgun metagenomics can be used to uncover pathogen/pathogen interactions in polymicrobial sepsis cases and their potential role in the clinical course of this condition.

Use of Antimicrobials for Bloodstream Infections in the Intensive Care Unit, a Clinically Oriented Review

Bloodstream infections (BSIs) in critically ill patients are associated with significant mortality. For patients with septic shock, antibiotics should be administered within the hour. Probabilistic treatment should be targeted to the most likely pathogens, considering the source and risk factors for bacterial resistance including local epidemiology. Source control is a critical component of the management. Sending blood cultures (BCs) and other specimens before antibiotic administration, without delaying them, is key to microbiological diagnosis and subsequent opportunities for antimicrobial stewardship. Molecular rapid diagnostic testing may provide faster identification of pathogens and specific resistance patterns from the initial positive BC. Results allow for antibiotic optimisation, targeting the causative pathogen with escalation or de-escalation as required. Through this clinically oriented narrative review, we provide expert commentary for empirical and targeted antibiotic choice, including a review of the evidence and recommendations for the treatments of extended-spectrum β-lactamase-producing, AmpC-hyperproducing and carbapenem-resistant Enterobacterales; carbapenem-resistant Acinetobacter baumannii; and Staphylococcus aureus. In order to improve clinical outcomes, dosing recommendations and pharmacokinetics/pharmacodynamics specific to ICU patients must be followed, alongside therapeutic drug monitoring.

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.

Childhood Invasive Bacterial Disease in Kathmandu, Nepal (2005-2013)

BACKGROUND

Invasive bacterial disease (IBD; including pneumonia, meningitis, sepsis) is a major cause of morbidity and mortality in children in low-income countries.

METHODS

We analyzed data from a surveillance study of suspected community-acquired IBD in children <15 years of age in Kathmandu, Nepal, from 2005 to 2013 before introduction of pneumococcal conjugate vaccines (PCV). We detailed the serotype-specific distribution of invasive pneumococcal disease (IPD) and incorporated antigen and PCR testing of cerebrospinal fluid (CSF) from children with meningitis.

RESULTS

Enhanced surveillance of IBD was undertaken during 2005-2006 and 2010-2013. During enhanced surveillance, a total of 7956 children were recruited of whom 7754 had blood or CSF culture results available for analysis, and 342 (4%) had a pathogen isolated. From 2007 to 2009, all 376 positive culture results were available, with 259 pathogens isolated (and 117 contaminants). Salmonella enterica serovar Typhi was the most prevalent pathogen isolated (167 cases, 28% of pathogens), followed by Streptococcus pneumoniae (98 cases, 16% pathogens). Approximately, 73% and 78% of pneumococcal serotypes were contained in 10-valent and 13-valent PCV, respectively. Most cases of invasive pneumococcal disease (IPD) were among children ≥5 years of age from 2008 onward. Antigen and PCR testing of CSF for pneumococci, Haemophilus influenzae type b and meningococci increased the number of these pathogens identified from 33 (culture) to 68 (culture/antigen/PCR testing).

CONCLUSIONS

S. enterica serovar Typhi and S. pneumoniae accounted for 44% of pathogens isolated. Most pneumococcal isolates were of serotypes contained in PCVs. Antigen and PCR testing of CSF improves sensitivity for IBD pathogens.

Knowledge, Attitude and Practice Regarding Staphylococcus pettenkoferi

Staphylococcus pettenkoferi is a coagulase-negative staphylococcus, first described in 2002. Using medical databases, i.e., Scopus, Web of Science, Pubmed, and Embase, we identified and analysed research, reports, and opinions dealing with S. pettenkoferi. Published data allow us to conclude that S. pettenkoferi is a human commensal, opportunistic bacterium and may be isolated from the environment and animals. The involvement of S. pettenkoferi in bloodstream infection and osteomyelitis has been described, but its clinical relevance is not fully understood, so far. This work summarizes knowledge about S. pettenkoferi and reveals the difficulties and rules for interpreting the results of microbiological tests, when S. pettenkoferi has been identified in the blood sample. Clinical and laboratory criteria, recommended by Centers for Disease Control and Prevention (CDC) and the third international consensus definitions of sepsis and septic shock (Sepsis-3), are important to determine whether the presence of bacteria in the sample is a consequence of an infection, contamination from the environment, or translocation of the bacteria outside the place of its natural existence. The precise identification of bacteria from the blood sample and recognizing the true bacteraemia are critical to implement the appropriate procedures and make decisions concerning the patient’s medical care.

Blood bacterial resistant investigation collaborative system (BRICS) report: a national surveillance in China from 2014 to 2019

BACKGROUND

In this first national bloodstream infection (BSI) surveillance program in China, we assessed the composition of pathogenic bacteria and the trends for antimicrobial susceptibility over a 6-year period in China.

METHODS

Blood bacterial isolates from patients at hospitals participating in the Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected from January 2014 to December 2019. Only the first isolate of a species per patient was eligible over the full study period. Antibiotic-susceptibility testing was conducted by agar-dilution or broth-dilution methods as recommended by the Clinical and Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.

RESULTS

During the study period, 27,899 bacterial strains were collected. Gram-positive organisms accounted for 29.5% (8244) of the species identified and Gram-negative organisms accounted for 70.5% (19,655). The most-commonly isolated organisms in blood cultures were Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, coagulase-negative Staphylococci, and Acinetobacter baumannii. The prevalence of multidrug-resistant organisms, such as E. coli, K. pneumoniae, A. baumannii was higher in tertiary hospitals, whereas extended-spectrum, β-lactamase-producing E. coli (ESBL-E. coli), carbapenem-resistant A. baumannii were more prevalent in economically-developing areas. The prevalence of methicillin-resistant S. aureus declined from 39.0% (73/187) in 2014 to 25.9% (230/889) in 2019 (p < 0.05). The prevalence of ESBL-E. coli dropped from 61.2% (412/673) to 51.0% (1878/3,683) over time (p < 0.05), and carbapenem-resistant E. coli remained low prevalence (< 2%; 145/9944; p = 0.397). In contrast, carbapenem-resistant K. pneumoniae increased markedly from 7.0% (16/229) in 2014 to 19.6% (325/1,655) in 2019 (p < 0.05).

CONCLUSION

E. coli and K. pneumoniae were the leading causes of BSI during the 6-year study period. The major resistant pathogens declined or remained stable, whereas carbapenem-resistant K. pneumoniae continued to increase, which poses a great therapeutic challenge for BSIs.

Using machine learning to predict blood culture outcomes in the emergency department: a single-centre, retrospective, observational study

OBJECTIVES

To develop predictive models for blood culture (BC) outcomes in an emergency department (ED) setting.

DESIGN

Retrospective observational study.

SETTING

ED of a large teaching hospital in the Netherlands between 1 September 2018 and 24 June 2020.

PARTICIPANTS

Adult patients from whom BCs were collected in the ED. Data of demographic information, vital signs, administered medications in the ED and laboratory and radiology results were extracted from the electronic health record, if available at the end of the ED visits.

MAIN OUTCOME MEASURES

The primary outcome was the performance of two models (logistic regression and gradient boosted trees) to predict bacteraemia in ED patients, defined as at least one true positive BC collected at the ED.

RESULTS

In 4885 out of 51 399 ED visits (9.5%), BCs were collected. In 598/4885 (12.2%) visits, at least one of the BCs was true positive. Both a gradient boosted tree model and a logistic regression model showed good performance in predicting BC results with area under curve of the receiver operating characteristics of 0.77 (95% CI 0.73 to 0.82) and 0.78 (95% CI 0.73 to 0.82) in the test sets, respectively. In the gradient boosted tree model, the optimal threshold would predict 69% of BCs in the test set to be negative, with a negative predictive value of over 94%.

CONCLUSIONS

Both models can accurately identify patients with low risk of bacteraemia at the ED in this single-centre setting and may be useful to reduce unnecessary BCs and associated healthcare costs. Further studies are necessary for validation and to investigate the potential clinical benefits and possible risks after implementation.