Identifying Serious Bacterial Infections in Febrile Young Infants

Febrile infants risk score at triage (FIRST) for the early identification of serious bacterial infections

We aimed to derive the Febrile Infants Risk Score at Triage (FIRST) to quantify risk for serious bacterial infections (SBIs), defined as bacteremia, meningitis and urinary tract infections. We performed a prospective observational study on febrile infants < 3 months old at a tertiary hospital in Singapore between 2018 and 2021. We utilized machine learning and logistic regression to derive 2 models: FIRST, based on patient demographics, vital signs and history, and FIRST + , adding laboratory results to the same variables. SBIs were diagnosed in 224/1002 (22.4%) infants. Among 994 children with complete data, age (adjusted odds ratio [aOR] 1.01 95%CI 1.01-1.02, p < 0.001), high temperature (aOR 2.22 95%CI 1.69-2.91, p < 0.001), male sex (aOR 2.62 95%CI 1.86-3.70, p < 0.001) and fever of ≥ 2 days (aOR 1.79 95%CI 1.18-2.74, p = 0.007) were independently associated with SBIs. For FIRST + , abnormal urine leukocyte esterase (aOR 16.46 95%CI 10.00-27.11, p < 0.001) and procalcitonin (aOR 1.05 95%CI 1.01-1.09, p = 0.009) were further identified. A FIRST + threshold of ≥ 15% predicted risk had a sensitivity of 81.8% (95%CI 70.5-91.0%) and specificity of 65.6% (95%CI 57.8-72.7%). In the testing dataset, FIRST + had an area under receiver operating characteristic curve of 0.87 (95%CI 0.81-0.94). These scores can potentially guide triage and prioritization of febrile infants.

Utility of the systemic immune-inflammation index to predict serious bacterial infections in infants with fever without a source

INTRODUCTION

This study analyzed the utility of the systemic immune-inflammation index (SII) in predicting serious bacterial infections (SBIs) in infants with fever without a source (FWS).

METHODS

Infants (aged 1-4 months) evaluated in the pediatric emergency department for FWS were divided into two groups: with SBI and without SBI. The efficacy of inflammatory markers in predicting SBI was compared.

RESULTS

The study included 223 infants with a mean age of 76.65 ± 25.42 days; 62 (27.8%) of them were included in the SBI group, and all of them were diagnosed with a urinary tract infection (UTI). The hospitalization rate and length of hospital stay were significantly higher in UTI patients (p < 0.001 for each). The mean SII was 795.76 ± 475.85 in the SBI group and 318.24 ± 300.70 in the non-SBI group, and there was a significant difference between the groups (p < 0.001). In diagnosis of SBI, the area under the curve values were found to be 0.89 [95% confidence interval (CI): 0.85-0.94] for C-reactive protein (CRP), 0.86 (95% CI: 0.81-0.91) for absolute neutrophil count (ANC), 0.84 (95% CI: 0.78-0.89) for the SII, and 0.81 (95% CI: 0.74-0.87) for WBC. In the multivariate logistic regression analysis, high CRP and SII values were found to be predictive factors for UTI without bacteremia (p < 0.001 and p = 0.008, respectively).

CONCLUSION

We found that high CRP and SII values could be predictive for UTI without bacteremia in infants with FWS. The SII may be preferred because it can be easily calculated using the hemogram results, is not accompanied by extra costs, and does not require further blood collection.