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Profile of Blood Biomarkers in Febrile Infants Under 90 Days Old With Invasive Bacterial Infection by Type of
Anna Sorolla-Anglés1, Borja Gómez2,3, Jose Antonio Alonso-Cadenas4,5
1From the Paediatrics Department, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT-CERCA), Sabadell.
Insights
Biomarker performance for infant invasive bacterial infections (IBI) varies by pathogen and infection type. Procalcitonin is best for ruling out Streptococcus agalactiae IBI, aiding accurate diagnosis.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Microbiology
- Biomarker Research
Background:
- Early identification of invasive bacterial infections (IBI) in febrile infants is critical for effective management.
- Standard blood biomarkers are used for risk evaluation but their diagnostic accuracy can be organism-dependent.
Purpose of the Study:
- To evaluate the diagnostic performance of standard biomarkers for invasive bacterial infections in infants.
- To analyze how biomarker sensitivity varies based on the causative pathogen and type of invasive bacterial infection.
Main Methods:
- Retrospective, multicenter study of 395 infants ≤90 days with IBI from 2008-2022.
- IBI definition included bacterial isolation or PCR detection in blood or cerebrospinal fluid.
- Analysis of standard biomarker cutoffs' sensitivity by pathogen and IBI type, with multivariate regression.
Main Results:
- Escherichia coli and Streptococcus agalactiae were the most common pathogens; bacteremia and bacteremic UTI were frequent IBI types.
- Biomarker responses differed significantly between E. coli and S. agalactiae infections.
- White blood cell (WBC) and absolute neutrophil count (ANC) sensitivities were below 50% for most pathogens and IBI types; procalcitonin showed high sensitivity for S. agalactiae.
Conclusions:
- Biomarker levels in febrile infants with IBI are influenced by the specific pathogen and infection site.
- Increases in WBC, ANC, and C-reactive protein are less pronounced in isolated bacteremias compared to bacteremic UTIs.
- Procalcitonin is the most sensitive biomarker for excluding S. agalactiae IBI, crucial for accurate diagnosis and preventing underdiagnosis.
Introduction:
Early identification of invasive bacterial infections (IBI) in febrile infants under 90 days is essential, with blood biomarkers widely used for their risk evaluation. However, their diagnostic performance may vary by causative organism or type of IBI.
Methods:
We conducted a retrospective, multicenter study of infants ≤90 days with IBI treated in pediatric emergency departments of 18 hospitals (Spain and Latin America) from 2008 to 2022. IBI was defined by isolation or polymerase chain reaction (PCR) detection of a pathogenic bacterium in blood or cerebrospinal fluid. Sensitivity of standard biomarker cutoffs was analyzed by pathogen and IBI type, with multivariate regression adjusting for age, sex, temperature, symptom duration and clinical presentation.
Results:
Of 395 infants, Escherichia coli (45.6%) and Streptococcus agalactiae (25.6%) were the most frequently isolated bacteria, and bacteremia (43.8%) and bacteremic urinary tract infection (41.3%) were the most frequent IBI. Biomarker responses varied by organism and IBI type. E. coli IBIs showed higher white blood cell (WBC) and absolute neutrophil (ANC) counts and C-reactive protein levels than S. agalactiae IBIs. Only procalcitonin had high sensitivity for S. agalactiae IBIs. Standard cutoffs for WBC and ANC showed sensitivities below 50% for all pathogens and types of IBI.
Conclusion:
Biomarker levels in young febrile infants with IBIs depend on IBI type and causing bacteria. Increases in WBC, ANC and C-reactive protein are lower in isolated bacteremias than in bacteremic urinary tract infections. Procalcitonin is the best biomarker for ruling out S. agalactiae IBIs. These distinctions are key to interpreting lab tests and preventing underdiagnosis of invasive infections.
