Reporting and Categorization of Blood Culture Contaminants in Infants and Young Children: A Scoping Review

Recovery of pathogens with implementation of a weight-based algorithm for pediatric blood cultures: an observational intervention study

BACKGROUND

Recovering pathogenic bacteria and yeast from pediatric blood cultures and reliably distinguishing between pathogens and contaminants are likely to be improved by increasing the volume of blood submitted to microbiology laboratories for culturing beyond the low volumes that have historically have been used. The primary aim of this study was to assess whether the pathogen recovery rate would increase after implementation of a weight-based algorithm for determining the intended volume of blood submitted for culturing. Secondary aims were to: 1) evaluate the effects of the algorithm implementation on the blood culture contamination rate; 2) determine whether pathogens might be found more often than contaminants in several as opposed to single bottles when more than one bottle is submitted; and 3) describe the microbiological findings for pathogens and contaminants in blood cultures by applying a clinical validation of true blood culture positivity.

METHODS

A pre-post comparison of positivity and contamination rates after increasing the theoretical blood volume and number of blood culture bottles was performed, on the basis of a clinical validation of blood culture findings as pathogens vs contaminants.

RESULTS

We examined 5327 blood cultures, including 186 with growth (123 true positives and 63 contaminated). The rate of true positive blood cultures significantly increased from 1.6% (42/2553) pre to 2.9% (81/2774, p = .002) post intervention. The rate of contaminated blood cultures did not change significantly during the study period (1.4% [35/2553] pre vs 1.0% [28/2774], p = .222) post intervention), but the proportion of contaminated cultures among all positive cultures decreased from 45% (35/77) pre to 26% (28/109, p = .005) post intervention. A microorganism that grew in a single bottle was considered a contaminant in 35% (8/23) of cases, whereas a microorganism that grew in at least two bottles was considered a contaminant in 2% (1/49, p < .001) of cases. According to common classification criteria relying primarily on the identity of the microorganism, 14% (17/123) of the recovered pathogens would otherwise have been classified as contaminants.

CONCLUSION

Implementation of a weight-based algorithm to determine the volume and number of blood cultures in pediatric patients is associated with an increase in the pathogen recovery rate.

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.

Blood culture quality and turnaround time of clinical microbiology laboratories in Chinese Teaching Hospitals: A multicenter study

PURPOSE

Blood culture (BC) remains the gold standard for the diagnosis of bloodstream infections. Improving the quality of clinical BC samples, optimizing BC performance, and accelerating antimicrobial susceptibility test (AST) results are essential for the early detection of bloodstream infections and specific treatments.

METHODS

We conducted a retrospective multicenter study using 450,845 BC specimens from clinical laboratories obtained from 19 teaching hospitals between 1 January 2021 and 31 December 2021. We evaluated key performance indicators (KPIs), turnaround times (TATs), and frequency distributions of processing in BC specimens. We also evaluated the AST results of clinically significant isolates for four different laboratory workflow styles.

RESULTS

Across the 10 common bacterial isolates (n = 16,865) and yeast isolates (n = 1011), the overall median (interquartile range) TATs of AST results were 2.67 (2.05-3.31) and 3.73 (2.98-4.64) days, respectively. The specimen collections mainly occurred between 06:00 and 24:00, and specimen reception and loadings mainly between 08:00 and 24:00. Based on the laboratory workflows of the BCs, 16 of the 19 hospitals were divided into four groups. Time to results (TTRs) from specimen collection to the AST reports were 2.35 (1.95-3.06), 2.61 (1.98-3.32), 2.99 (2.60-3.87), and 3.25 (2.80-3.98) days for groups I, II, III, and IV, respectively.

CONCLUSION

This study shows the related BC KPIs and workflows in different Chinese hospitals, suggesting that laboratory workflow optimization can play important roles in shortening time to AST reports and initiation of appropriate timely treatment.

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.

Management and Outcome of Febrile Infants ≤60 days, With Emphasis on Infants ≤21 Days Old, in Swedish Pediatric Emergency Departments

BACKGROUND

Management of febrile infants ≤60 days of age varies, and the age for routine investigations and antibiotic-treatment is debated. The American Academy of Pediatrics recommended age threshold for lumbar puncture (LP) is 21 days and for blood culture 60 days. We describe management and adverse outcome of febrile infants ≤60 days old, in Sweden.

METHODS

Retrospective cross-sectional study of infants ≤60 days of age with fever without source evaluated in 4 University pediatric emergency departments, between 2014 and 2017. Adverse outcome was defined as delayed-treated invasive bacterial infection (IBI: meningitis or bacteremia).

RESULTS

We included 1701 infants. In infants ≤21 days old, LP was performed in 16% (95% CI: 12-20) and blood culture in 43% (95% CI: 38-48). Meningitis was diagnosed in 5 (1.3%; 95% CI: 0.4-3.0) and bacteremia in 12 (4.5%; 95% CI: 2.6-7.0) infants. Broad-spectrum antibiotics were not administered to 66% (95% CI: 61-71), of which 2 (0.8%; 95% CI: 0.1-2.8) diagnosed with IBI (1 meningitis and 1 bacteremia). In the 29-60 days age group, blood culture was performed in 21% (95% CI: 19-24), and broad-spectrum antibiotics were not administered to 84% (95% CI: 82-86), with no case of delayed-treated bacteremia.

CONCLUSIONS

The rates of LP, blood culture and broad-spectrum antibiotics were low. Despite that, there were few delayed-treated IBIs, but 2 of the 17 infants ≤21 days of age with IBI were not timely treated, which prompts the need for a safer approach for this age group. Also, the utility of routine blood culture for all febrile infants 29-60 days old could be questioned.

Clinical decision rule for obtaining peripheral blood cultures in febrile oncology patients

BACKGROUND

The utility of peripheral blood cultures in pediatric oncology patients presenting with fever is controversial. A recent systematic review showed that about one in 40 bloodstream infections (BSIs) would be missed if only central venous line (CVL) cultures are obtained.

OBJECTIVE

To derive a clinical decision rule for obtaining peripheral blood cultures in pediatric oncology patients presenting to a pediatric emergency department (PED) with fever and a CVL.

DESIGN/METHOD

A retrospective chart review was performed on pediatric oncology patients referred to the PED for fever while on therapy. Logistic regression with a random intercept was used to determine independent predictors of BSI and generate a prediction model for obtaining peripheral blood cultures. The decision rule was generated from the best performance as measured by a receiver operator curve. Bootstrapping analysis was performed for internal validation.

RESULTS

Predictors that were significant and independently associated with positive peripheral blood cultures included vasopressor support (odds ratio [OR] 16.5, 95% confidence interval [CI]: 2.80-97.71), acute myeloid leukemia (AML) diagnosis (OR 6.9, 95% CI: 1.81-25.98), hypotension (OR 4.0, 95% CI: 1.05-15.17), mucositis (OR 8.2, 95% CI: 2.48-27.01), and maximum temperature in PED ≥39°C (OR 6.6, 95% CI: 2.36-18.20). The area under the curve (AUC) for this model was 0.90 (95% CI: 0.82-0.97) in the derivation cohort and 0.90 (95% CI: 0.81-0.98) after the internal validation.

CONCLUSIONS

We derived a clinical prediction model for deciding when to obtain peripheral blood cultures in febrile oncology patients with CVLs on active therapy. Future studies should focus on prospective and external validation of this diagnostic prediction tool.

Comparing blood culture contamination rates by different sampling methods in a paediatric emergency department

AIM

Blood culture contamination (BCC) can cause unnecessary hospitalisations and inappropriate use of antibiotics. The aim of this study was to find risk factors associated with BCCs in children and to compare contamination rates between open and closed blood culture collection systems.

METHODS

Data were prospectively collected regarding blood cultures obtained in the paediatric emergency department from February 26, 2020, to September 30, 2020, based on the method of drawing blood reported by the obtaining physician. A comparison between contaminated and non-contaminated blood cultures was performed. We also compared the composition of the contaminations in the study period to the same period in 2019.

RESULTS

A total of 512 blood cultures were included, 33 (6.4%) of which were contaminated. The only parameter that was associated with an increased rate of contamination by 2.34 fold (95% CI 1.1-4.99, P = 0.028) was obtaining blood through an 'open' system, using a syringe connected to a needle in order to draw blood from an open ended needle. The proportion of contaminations originating from oral flora decreased in the study period by 44.7% as compared to the same period in the previous year (13% vs. 23.5%, P = 0.056).

CONCLUSIONS

'Open system' method, which is commonly used in paediatric emergency departments for blood culture obtainment, was associated with an increase in BCC. Adherence to blood cultures obtainment guidelines, even at the price of two different blood tests, is important in order to reduce BCC rates in children.

Time to Blood Culture Positivity by Pathogen and Primary Service

OBJECTIVES

Initiation and continuation of empirical antimicrobial agents for a 48-72-hour observation period is routine practice in the diagnosis and treatment of infants and children with concern for bacteremia. We examined blood cultures at a freestanding pediatric hospital over a 6-year period to determine the time to positivity.

METHODS

Data were extracted for all patients who were hospitalized and had blood cultures drawn between January 2013 and December 2018. Time to positivity was calculated on the basis of date and time culture was collected compared with date and time growth was first reported.

RESULTS

Over a 6-year period, 89 663 blood cultures were obtained, of which 6184 had positive results. After exclusions, a total of 2121 positive blood culture results remained, including 1454 (69%) pathogens and 667 contaminants (31%). For all positive blood culture results, the number and percentage positive at 24, 36, and 48 hours were 1441 of 2121 (68%), 1845 of 2121 (87%) and 1970 of 2121 (93%), respectively. One hundred twenty-five (66 pathogens, 59 contaminants) of the 89 663 cultures (0.14%) yielded positive results between 36 and 48 hours, indicating that 719 patients would need to be treated for 48 hours rather than 36 hours to prevent 1 case of antibiotic termination before positive result. Median times to positive result by pathogen and service line are presented.

CONCLUSIONS

This study reveals that ≤36 hours may be a sufficient period of observation for infants and children started on empirical antimicrobial agents for concern for bacteremia. These findings highlight opportunities for antimicrobial stewardship to limit antimicrobial .

Time to Positive Blood and Cerebrospinal Fluid Cultures in Febrile Infants ≤60 Days of Age

OBJECTIVES

To determine the time to positivity for bacterial pathogens and contaminants in blood and cerebrospinal fluid (CSF) cultures in a cohort of febrile infants ≤60 days of age.

METHODS

This was a secondary analysis of prospective observational multicenter study of noncritically ill infants ≤60 days of age with temperatures ≥38°C and blood cultures (December 2008 to May 2013). The main outcome was time to positivity for bacterial pathogens and contaminants.

RESULTS

A total of 256 of 303 (84.49%) patients with positive blood cultures, and 73 of 88 (82.95%) with positive CSF cultures met inclusion criteria. Median time (interquartile range [IQR]) to positivity for blood cultures was 16.6 hours (IQR 12.6-21.9) for bacterial pathogens (n = 74) and 25.1 hours (IQR 19.8-33.0) for contaminants (n = 182); P < .001. Time to bacterial pathogen positivity was similar in infants 0 to 28 days of age (15.8 hours [IQR 12.6-21.0]) and 29 to 60 days of age (17.2 [IQR 12.9-24.3]; P = .328). Median time to positivity for CSF was 14.0 hours (IQR 1.5-21.0) for bacterial pathogens (n = 22) and 40.5 hours (IQR 21.2-62.6) for contaminants (n = 51); P < .001. A total of 82.4% (95% confidence interval, 71.8-90.3) and 81.8% (95% confidence interval, 59.7%-94.8%) of blood and CSF cultures showed bacterial pathogen positivity within 24 hours.

CONCLUSIONS

Among febrile infants ≤60 days of age, time to blood and CSF positivity was significantly shorter for bacterial pathogens than contaminants. Most blood and CSF cultures for bacterial pathogens were positive within 24 hours. With our findings, there is potential to reduce duration of hospitalization and avoid unnecessary antibiotics.

Epidemiology and Antimicrobial Susceptibility of Invasive Bacterial Infections in Children-A Population-Based Study From Norway

OBJECTIVE

To describe epidemiology and antimicrobial susceptibility testing (AST) data of bacteria causing invasive infections in Norwegian children (0-18 years).

METHODS

Population-based observational study using prospectively collected AST data from the Norwegian Surveillance System of Antimicrobial Resistance from 2013 to 2017. We included all clinically relevant bacterial isolates (blood and cerebrospinal fluid), and compared incidence of invasive infections and AST data in isolates from children and adults.

RESULTS

We included 1173 isolates from children and 44,561 isolates from adults. Staphylococcus aureus accounted for 220/477 (46.2%, 95% CI: 41.6-50.7) of all isolates in schoolchildren (6-18 years). Compared with Streptococcus pneumonia isolates from adults (N = 2674), we observed higher nonsusceptibility rates to penicillin in isolates from children (N = 151), 11.9% versus 5.8%, P < 0.01; also higher resistance rates to erythromycin (11.3% vs. 4.9%, P < 0.01), clindamycin (9.3% vs. 3.6%, P < 0.001), and trimethoprim/sulfamethoxazole (17.9% vs. 6.4%, P < 0.001). Compared with Escherichia coli isolates in adults (N = 9073), we found lower rates of ESBL in isolates from children (N = 212), 2.4% versus 6.4%, P < 0.05.

CONCLUSION

The study indicates the importance of microbiologic surveillance strategies in children and highlights the need for pediatric AST data. The high rates of nonsusceptibility to commonly used antibiotics among S. pneumoniae in children and the high burden of invasive S. aureus infections in schoolchildren calls for modifications of Norwegian guidelines.

United States' Emergency Department Visits for Fever by Young Children 2007-2017

Introduction

Our goal in this study was to estimate rates of emergency department (ED) visits for fever by children <2 years of age, and evaluate frequencies of testing and treatment during these visits.

Methods

We performed a cross-sectional study of ED encounters from 2007–2017 using the National Hospital Ambulatory Medical Care Survey, a cross-sectional, multi-stage probability sample survey of visits to nonfederal United States EDs. We included encounters with a visit reason of “fever” or recorded fever in the ED. We report demographics and management strategies in two groups: infants ≤90 days in age; and children 91 days to <2 years old. For patients 91 days to <2 years, we compared testing and treatment strategies between general and pediatric EDs using chi-squared tests.

Results

Of 1.5 billion encounters over 11 years, 2.1% (95% confidence interval [CI], 1.9–2.2%) were by children <2 years old with fever. Two million encounters (95% CI, 1.7–2.4 million) were by infants ≤90 days, and 28.4 million (95% CI, 25.5–31.4 million) were by children 91 days to <2 years. Among infants ≤90 days, 27.6% (95% CI, 21.1–34.1%) had blood and 21.3% (95% CI, 13.6–29.1%) had urine cultures; 26.8% (95% CI, 20.9–32.7%) were given antibiotics, and 21.1% (95% CI, 15.3–26.9%) were admitted or transferred. Among patients 91 days to <2 years in age, 6.8% (95% CI, 5.8–7.8%) had blood and 7.7% (95% CI 6.1–9.4%) had urine cultures; 40.5% (95% CI, 40.5–40.5%) were given antibiotics, and 4.4% (95% CI, 3.5–5.3%) were admitted or transferred. Patients 91 days to <2 years who were evaluated in general EDs had higher rates of radiography (27.1% vs 15.2%; P<0.01) and antibiotic utilization (42.3% vs 34.2%; P<0.01), but lower rates of urine culture testing (6.4% vs 11.6%, p = 0.03), compared with patients evaluated in pediatric EDs.

Conclusion

Approximately 180,000 patients ≤90 days old and 2.6 million patients 91 days to <2 years in age with fever present to US EDs annually. Given existing guidelines, blood and urine culture performance was low for infants ≤90 days old. For children 91 days to <2 years, rates of radiography and antibiotic use were higher in general EDs compared to pediatric EDs. These findings suggest opportunities to improve care among febrile young children in the ED.

Blood culture sampling rate in hospitalised children as a quality indicator for diagnostic stewardship

PURPOSE

Recommendations regarding the optimal number of blood cultures in children are not available. The aim of this article is to describe the correlation between blood culture (BC) rates and laboratory-confirmed bloodstream infection (LCBSI) rates, on different paediatric wards of a tertiary-care centre in Germany.

METHODS

We conducted a retrospective cohort study in a paediatric university hospital, from 1st January to 31st December 2018. All blood cultures collected from neonatal (NICU) and paediatric intensive-care units (PICU), haematology/oncology, and general paediatric wards were included. There were no exclusion criteria. BC taken/1000 patients-days (BC rates/BCR) and LCBSI/1000 patient-days at risk (LCBSI rates) were calculated for each unit.

RESULTS

A total of 6040 patients were admitted to the hospital with 3114 of them into wards studied. Of the 3072 BCs collected, 200 (6.5%) were positive. Collection of BCs was performed in 51/77 (66.2%) of admitted patients on NICU, in 151/399 (37.8%) of PICU patients, in 163/755 (21.6%) of haematology/oncology patients, and in 281/1883 (14.9%) of children on general paediatric wards. Gram-positive bacteria were the most commonly detected organisms in blood cultures from all wards with exception of NICU. The BCR in NICU, PICU, haematology/oncology wards, and general wards were 61.6, 196.2, 358.4, and 52.3, respectively. Excluding commensal pathogens and possible contaminations, the LCBSI rates in the same units were 2.4, 5.6, 4.4, and 1.0, respectively.

CONCLUSION

We found different BCR values according the ward studied, being higher in patients with high risk of bloodstream infection such as haematology/oncology patients.