Serious Bacterial Infections in Febrile Infants

Serious bacterial infections in infants presenting with fever pose a significant global challenge due to their non-specific clinical features and the high risk of invasive disease in this age group. Infants under three months are particularly vulnerable to bacteraemia, bacterial meningitis and urinary tract infections, with a pooled prevalence of invasive bacterial illness reported at up to 10–15 per cent in some settings. The immature immune system of neonates, combined with subtle or absent localising signs, demands a cautious yet evidence-based approach to investigation and management. Standard practice often involves a combination of clinical assessment, laboratory markers such as C-reactive protein and procalcitonin, and, where indicated, blood and cerebrospinal fluid cultures. Despite advances in risk-stratification algorithms and less invasive diagnostics, variations in antibiotic use, hospital admission rates and resource utilisation persist across health systems. Current research seeks to refine predictive tools, integrate novel biomarkers and streamline pathways to ensure timely identification of infants at high risk while avoiding unnecessary interventions in those at low risk.

Research from Nature Portfolio

A novel risk-scoring system for febrile infants under three months has demonstrated high discriminative power for detecting serious bacterial infections. The score integrates demographic factors, vital signs and simple history items, with an enhanced model incorporating laboratory variables such as procalcitonin and urine leukocyte esterase. In a prospective cohort, a threshold in the enhanced model yielded sensitivity above eighty per cent and specificity around sixty-five per cent, with an overall area under the curve approaching 0.9. These findings suggest that a combined clinical and laboratory risk score could guide triage decisions, prioritising infants for further investigation and early antimicrobial therapy.

Serious Bacterial Infections in Febrile Infants publication trend

The graph below shows the total number of articles in serious bacterial infections in febrile infants across all publications each year (not limited to Nature Index journals).

Technical terms

Serious bacterial infection (SBI): An infection by bacteria resulting in invasive disease such as bacteraemia, meningitis or urinary tract infection.

Bacteraemia: Presence of bacteria in the bloodstream, often confirmed by blood culture.

Procalcitonin: A protein biomarker that rises in the blood during bacterial infections, used to support diagnostic and antibiotic-stewardship decisions.

Host RNA expression signature: A pattern of gene expression in blood cells that can distinguish between different types of infection.

Triage: The initial clinical assessment process used to determine the urgency and prioritisation of patient care.

References

1. Changing Epidemiology of Serious Bacterial Infections in Febrile Infants without Localizing Signs. PLOS ONE (2010).
2. Approach to Neonates and Young Infants with Fever without a Source Who Are at Risk for Severe Bacterial Infection. Mediators of Inflammation (2018).
3. Febrile infants risk score at triage (FIRST) for the early identification of serious bacterial infections. Scientific Reports (2023).
4. Host RNA Expression Signatures in Young Infants with Urinary Tract Infection: A Prospective Study. International Journal of Molecular Sciences (2024).
5. Conundrums in the Management of Febrile Infants under Three Months of Age and Future Research. Antibiotics (2024).
6. Respiratory viral detection in the plasma and cerebrospinal fluid (CSF) of young febrile infants. Influenza and Other Respiratory Viruses (2024).