UNASSIGNED: Management of young febrile infants is challenging. Therefore, several guidelines have been developed over the last decades. However, knowledge regarding the impact of introducing guidelines for febrile infants is limited. We assessed the impact of and adherence to a novel guideline for managing febrile infants aged ≤59 days.
UNASSIGNED: This retrospective cross-sectional study was conducted in 2 pediatric emergency departments in Sweden between 2014 and 2021. We compared the management of infants aged ≤59 days with fever without a source (FWS) and the diagnosis of serious bacterial infections (SBIs) before and after implementing the new guideline.
UNASSIGNED: We included 1,326 infants aged ≤59 days with FWS. Among infants aged ≤21 days, urine cultures increased from 49% to 67% (p = 0.001), blood cultures from 43% to 63% (p < 0.001), lumbar punctures from 16% to 33% (p = 0.003), and antibiotics from 38% to 57% (p = 0.002). Only 39 of 142 (28%) infants aged ≤21 days received recommended management. The SBI prevalence was 16.7% (95% CI, 11.0-23.8) and 17.6% (95% CI, 11.7-24.9) before and after the implementation, respectively. Among infants aged ≤59 days, there were 3 infants (0.6%; 95% CI, 0.1-1.7) in the pre-implementation period and 3 infants (0.6%; 95% CI, 0.1-1.7) in the post-implementation period with delayed treated urinary tract infections.
UNASSIGNED: Investigations and antibiotics increased significantly after implementation of the new guideline. However, doing more did not improve the diagnosis of SBIs. Thus, the low adherence to the new guideline may be considered justified. Future research should consider strategies to safely minimize interventions when managing infants with FWS.

UNASSIGNED: Procalcitonin (PCT) is a useful biomarker in the initial evaluation of febrile infants for serious bacterial infections (SBIs). However, PCT is not always available locally and must at times be frozen and shipped to a reference laboratory for research studies. We sought to compare PCT measured locally versus centrally at a reference laboratory during a research study.
UNASSIGNED: This was a secondary analysis of a multicenter study of febrile infants ≤60 days evaluated for SBIs from June 2016 to April 2019. A PCT cutoff value of 0.5 ng/mL was used to stratify infants at low-versus high-risk of SBIs. Statistical analyses consisted of Spearman\'s correlation, Bland-Altman difference plotting, Passing-Bablok regression, Deming regression, and Fisher\'s exact testing at the 0.5 ng/mL threshold.
UNASSIGNED: 241 febrile infants had PCT levels measured both locally and at the reference laboratory. PCT levels measured locally on 5 different platforms and from the frozen research samples demonstrated strong Spearman\'s correlation (ρ = 0.83) and had similar mean PCT values with an average relative difference of 0.02%. Eleven infants with SBIs had PCT values < 0.5 ng/mL in both the clinical and research samples. Six other infants had differences in SBI prediction based on PCT values at the 0.5 ng/mL threshold between the clinical and research platforms.
UNASSIGNED: We found no significant differences in detection of febrile infants at high risk for SBI based on locally (on multiple platforms) versus centrally processed PCT. Testing at a central reference laboratory after freezing and shipping is an accurate and reliable alternative for research studies or when rapid turnaround is not required.

UNASSIGNED: Hyperpyrexia has been associated with a greater prevalence of bacterial infections in the pediatric population, which prior to routine childhood vaccinations, has led to invasive testing and empiric antibiotic use for urinary tract infections, bacterial pneumonia, bacteremia, and bacterial meningitis. Since the implementation of routine childhood vaccinations, the prevalence of serious bacterial infections (SBIs) has declined. This study aims to determine if there is an association between hyperpyrexia and serious bacterial infections in well-appearing febrile pediatric patients presenting to the emergency department (ED).
UNASSIGNED: This is a cross-sectional study conducted between January 1, 2019, and December 31, 2019, at a single urban tertiary care pediatric ED. Patients were included if they were between 61 days and ≤18 years old presenting with a chief complaint of fever. Patients were excluded if they received antibiotics within 3 days of presentation, underwent surgical procedures within 2 weeks of presentation, had an ED visit for febrile illness within 2 weeks of study visit, were transferred from another institution, or were ill appearing. Prevalence of SBI was described and compared by presence of hyperpyrexia, age group, chronic medical condition, gender, and vaccination status. Logistic regression was used to analyze the association between SBIs and hyperpyrexia.
UNASSIGNED: Of the 3862 charts reviewed, 2565 patients were included. The prevalence of SBI was 5.6%. A total of 413 patients presented with hyperpyrexia. Of the patients with hyperpyrexia, 31 (7.5%) had a serious bacterial infection. Hyperpyrexia was not significantly associated with SBIs in our logistic regression models (adjusted Odds Ratio 1.40, 95% confidence interval 0.92-2.12).
UNASSIGNED: Serious bacterial infections were uncommon in our population. There is no statistically significant association between hyperpyrexia and SBIs in well-appearing pediatric patients presenting to the ED with fever. The lack of a statistically significant association between hyperpyrexia and SBIs argues that clinicians should be cautious using hyperpyrexia as an independent risk factor for SBIs. More research is needed to identify independent and grouped SBI risk factors in well-appearing pediatric patients presenting to the ED.

The evaluation and management of young infants presenting with fever remains an area of significant practice variation. While most well-appearing febrile young infants have a viral illness, identifying those at risk for invasive bacterial infections, specifically bacteremia and bacterial meningitis, is critical. This statement considers infants aged ≤90 days who present with a rectal temperature ≥38.0°C but appear well otherwise. Applying recent risk-stratification criteria to guide management and incorporating diagnostic testing with procalcitonin are advised. Management decisions for infants meeting low-risk criteria should reflect the probability of disease, consider the balance of risks and potential harm, and include parents/caregivers in shared decision-making when options exist. Optimal management may also be influenced by pragmatic considerations, such as access to diagnostic investigations, observation units, tertiary care, and follow-up. Special considerations such as temperature measurement, risk for invasive herpes simplex infection, and post-immunization fever are also discussed.

Febrile infections in children are a common cause of presentation to the emergency department (ED). While viral infections are usually self-limiting, sometimes bacterial illnesses may lead to sepsis and severe complications. Inflammatory biomarkers such as C reactive protein (CRP) and procalcitonin are usually the first blood exams performed in the ED to differentiate bacterial and viral infections; nowadays, a better understanding of immunochemical pathways has led to the discovery of new and more specific biomarkers that could play a role in the emergency setting. The aim of this narrative review is to provide the most recent evidence on biomarkers and predictor models, combining them for serious bacterial infection (SBI) diagnosis in febrile children. Literature analysis shows that inflammatory response is a complex mechanism in which many biochemical and immunological factors contribute to the host response in SBI. CRP and procalcitonin still represent the most used biomarkers in the pediatric ED for the diagnosis of SBI. Their sensibility and sensitivity increase when combined, and for this reason, it is reasonable to take them both into consideration in the evaluation of febrile children. The potential of machine learning tools, which represent a real novelty in medical practice, in conjunction with routine clinical and biological information, may improve the accuracy of diagnosis and target therapeutic options in SBI. However, studies on this matter are not yet validated in younger populations, making their relevance in pediatric precision medicine still uncertain. More data from further research are needed to improve clinical practice and decision making using these new technologies.

Serious bacterial infections (SBIs) are linked to unplanned hospital admissions and a high mortality rate. The early identification of SBIs is crucial in clinical practice.
This study aims to establish and validate clinically applicable models designed to identify SBIs in patients with infective fever.
Clinical data from 945 patients with infective fever, encompassing demographic and laboratory indicators, were retrospectively collected from a 2200-bed teaching hospital between January 2013 and December 2020. The data were randomly divided into training and test sets at a ratio of 7:3. Various machine learning (ML) algorithms, including Boruta, Lasso (least absolute shrinkage and selection operator), and recursive feature elimination, were utilized for feature filtering. The selected features were subsequently used to construct models predicting SBIs using logistic regression (LR), random forest (RF), and extreme gradient boosting (XGBoost) with 5-fold cross-validation. Performance metrics, including the receiver operating characteristic (ROC) curve and area under the ROC curve (AUC), accuracy, sensitivity, and other relevant parameters, were used to assess model performance. Considering both model performance and clinical needs, 2 clinical timing-sequence warning models were ultimately confirmed using LR analysis. The corresponding predictive nomograms were then plotted for clinical use. Moreover, a physician, blinded to the study, collected additional data from the same center involving 164 patients during 2021. The nomograms developed in the study were then applied in clinical practice to further validate their clinical utility.
In total, 69.9% (661/945) of the patients developed SBIs. Age, hemoglobin, neutrophil-to-lymphocyte ratio, fibrinogen, and C-reactive protein levels were identified as important features by at least two ML algorithms. Considering the collection sequence of these indicators and clinical demands, 2 timing-sequence models predicting the SBI risk were constructed accordingly: the early admission model (model 1) and the model within 24 hours of admission (model 2). LR demonstrated better stability than RF and XGBoost in both models and performed the best in model 2, with an AUC, accuracy, and sensitivity of 0.780 (95% CI 0.720-841), 0.754 (95% CI 0.698-804), and 0.776 (95% CI 0.711-832), respectively. XGBoost had an advantage over LR in AUC (0.708, 95% CI 0.641-775 vs 0.686, 95% CI 0.617-754), while RF achieved better accuracy (0.729, 95% CI 0.673-780) and sensitivity (0.790, 95% CI 0.728-844) than the other 2 approaches in model 1. Two SBI-risk prediction nomograms were developed for clinical use based on LR, and they exhibited good performance with an accuracy of 0.707 and 0.750 and a sensitivity of 0.729 and 0.927 in clinical application.
The clinical timing-sequence warning models demonstrated efficacy in predicting SBIs in patients suspected of having infective fever and in clinical application, suggesting good potential in clinical decision-making. Nevertheless, additional prospective and multicenter studies are necessary to further confirm their clinical utility.

We aimed to assess the prevalence of serious bacterial infections (SBIs) in febrile infants < 90 days of age with SARS-CoV-2 infection versus SARS-CoV-2-negative febrile infants. A retrospective cohort study was conducted in a tertiary pediatric emergency department between March 2020 and October 2022. Febrile infants < 90 days of age who underwent SARS-CoV-2 testing were included. SBIs were defined as urinary tract infection (UTI), bacteremia, and/or bacterial meningitis; bacteremia and bacterial meningitis were considered invasive bacterial infections (IBIs). SBIs rates were compared between SARS-CoV-2-positive and negative infants and stratified by age. We included 779 infants: 221 (28.4%) SARS-CoV-2-positive and 558 (71.6%) SARS-CoV-2-negative. The SBI rate in the SARS-CoV-2-positive group was 5.9% vs 22.9% in the SARS-CoV-2-negative group (p < 0.001; relative risk (RR) 0.26; [95% CI 0.15-0.44]); the most common infections were UTI (5.4% vs 22.0%; p < 0.001). The IBI rate was 0.5% in the SARS-CoV-2-positive group vs. 3.2% in the negative group (p = 0.024; RR 0.14 [95% CI 0.02-1.04]). There were no cases of bacterial meningitis in the positive infants. SARS-CoV-2-positive infants > 28 days of age had a decreased likelihood of SBI (RR 0.22 [95% CI 0.11-0.43]), with no cases of IBI identified.     Conclusions: Febrile infants < 90 days of age with SARS-CoV-2 infection are at significantly lower risk of SBIs than those who are SARS-CoV-2-negative. Nevertheless, the rate of UTI remains considerable in SARS-CoV-2-positive infants. SARS-CoV-2 detection may be relevant in considering IBI risk for well-appearing febrile infants 29-89 days of age. What is Known: • Febrile infants with laboratory-confirmed viral infections have a significantly lower risk of serious bacterial infections when compared to those without them. Data focusing on very young febrile infants with a SARS-CoV-2 infection is still limited. What is New: • Young febrile infants with SARS-CoV-2 infection are at significantly lower risk of serious bacterial infections than those who are SARS-CoV-2-negative. Nevertheless, the rate of urinary tract infection remains considerable. SARS-CoV-2 detection may be relevant in considering invasive bacterial infection risk for well-appearing febrile infants 29-89 days of age.

OBJECTIVE: We aimed to evaluate the impact of respiratory symptoms and positive viral testing on the risk of serious bacterial infections (SBIs).
METHODS: A retrospective study was conducted that included infants (0-60 days) presenting with a fever between 2001 and 2022 at a tertiary hospital in northern Israel. Demographic, clinical, and laboratory parameters were collected, and risk factors for SBIs were analyzed.
RESULTS: Data from a total of 3106 infants, including data from blood, urine, and CSF cultures, were obtained in 96.6%, 89%, and 29% of cases, respectively. A fever without respiratory symptoms (fever only) was present in 1312 infants, while 1794 had a fever and respiratory symptoms-427 were positive for a respiratory virus (virus+), 759 tested negative (virus-), and 608 were not tested. The SBI rate was 5.1% vs. 7.5% in the fever-and-respiratory group vs. the fever-only group (p = 0.004, OR = 0.65 (95% CI = 0.49-0.88)) and 2.8% vs. 7% in the virus+ vs. virus- group (p = 0.002, OR = 0.385, (95% CI = 0.203-0.728)). The male gender, an age < 1 month, leukocytosis > 15 × 109/L, or a CRP > 2 mg/dL increased the risk of SBIs. Respiratory symptoms or a confirmed viral infection reduced the risk of SBIs in the presence of the above risk factors.
CONCLUSIONS: Respiratory symptoms and a positive viral test decreased the risk of SBIs. Combining rapid viral testing with clinical variables may identify low-risk infants. Despite the relatively low risk of SBIs in individuals with viral infections, conducting prospective studies remains essential for accurately predicting the occurrence of these potentially life-threatening infections.

Adjusting the chronological age of preterm infants according to their gestational age is a widely accepted practice in the field of neurodevelopment. It has been suggested for the assessment of preterm infants with suspected infection, but has been poorly validated. Correcting for chronological age is especially critical in infants with a chronological age above 3 months, but a corrected age below 3 months due to the differences in assessment protocols. This study assessed the difference in incidence of serious bacterial infection (SBI) according to chronological and corrected age in preterm infants. A retrospective analysis of pediatric emergency department (PED) presentations was conducted for all 448 preterm infants born in between January 2010 and August 2019. Of the 448 preterm infants, 204 (46%) presented at one of 3 PEDs in Jerusalem, Israel, during their first year of life. Overall, 141 (31.4%) presented with fever and were included in the study. The infants were divided into 3 age groups: 1-corrected age >3 months; 2-chronological age >3 months, but corrected age <3 months; 3-chronological and corrected age <3 months. SBI was diagnosed in 2.6%, 16.7%, and 33.3% of the infants in groups 1, 2 and 3, respectively; (p < 0.01, p = 0.17, p < 0.001). The incidence of SBI in the control group of 300 term infants <3 months presenting to the PED due to fever was 15.3%. Preterm infants with a corrected age <3 months are at increased risk for SBI, similarly to term infants <3 months of age. Age correction should thus be considered for preterm infants presenting with fever.

UNASSIGNED: Procalcitonin testing is recommended to discriminate febrile young infants at risk of serious bacterial infections (SBI). However, this test is not available in many clinical settings, limited largely by cost. This study sought to evaluate contemporary real-world costs associated with the usual care of febrile young infants, and estimate impact on clinical trajectory and costs when incorporating procalcitonin testing.
UNASSIGNED: We assessed hospital-level door-to-discharge costs of all well-appearing febrile infants aged ≤60 days, evaluated at a tertiary paediatric hospital between April/2016 and March/2019. Emergency Department and inpatient expense data for usual care were obtained from the institutional general ledger, validated by the provincial Ministry of Health. These costs were then incorporated into a probabilistic model of risk stratification for an equivalent simulated cohort, with the addition of procalcitonin.
UNASSIGNED: During the 3-year study period, 1168 index visits were included for analysis. Real-world median costs-per-infant were the following: $3266 (IQR $2468 to $4317, n=93) for hospitalized infants with SBIs; $2476 (IQR $1974 to $3236, n=530) for hospitalized infants without SBIs; $323 (IQR $286 to $393, n=538) for discharged infants without SBIs; and, $3879 (IQR $3263 to $5297, n=7) for discharged infants subsequently hospitalized for missed SBIs. Overall median cost-per-infant of usual care was $1555 (IQR $1244 to $2025), compared to a modelled cost of $1389 (IQR $1118 to $1797) with the addition of procalcitonin (10.7% overall cost savings; $1,816,733 versus $1,622,483). Under pessimistic and optimistic model assumptions, savings were 5.9% and 14.9%, respectively.
UNASSIGNED: Usual care of febrile young infants is variable and resource intensive. Increased access to procalcitonin testing could improve risk stratification at lower overall costs.