Title : How should bacteriological sampling be stratified in paediat-2 ric septic arthritis? A narrative review
Abstract:
Introduction: Joint aspiration remains the gold-standard and an urgent step in the diagnosis of paediatric Septic Arthritis (SA), conferring both diagnostic and therapeutic value, in contrast to its role in acute haematogenous osteomyelitis. The bacteriological profile of paediatric SA is highly age-dependent: Kingella kingae predominates in children younger than 4 years, whereas Staphylococcus aureus—including Panton–Valentine Leukocidin (PVL)-producing and methicillin-resistant (MRSA) strains—predominates thereafter. No previous review has specifically addressed when bacteriological sampling is essential and when it may reasonably be omitted. This narrative review critically appraises the evidence through nine clinical questions and proposes a risk-stratified conceptual framework integrating emerging data on bacterial virulence factors.
Methods: A structured literature search was conducted in PubMed/MEDLINE, Embase, and the Cochrane Library (January 1997–March 2026), following the recommendations of Pai et al. and with support from an experienced research librarian, limited to English- and French-language publications. Guidelines from the Pediatric Infectious Diseases Society/Infectious Diseases Society of America (PIDS/IDSA, 2021 and 2023) and the European Society for Paediatric Infectious Diseases (ESPID, 2017), together with national guidance (Health Protection Agency, Groupe de Pathologie Infectieuse Pédiatrique), were specifically sought. The search identified 299 publications; after abstract screening (91 excluded), 208 articles underwent full-text review, and 90 were ultimately retained. As a narrative review, no formal PRISMA-compliant protocol was followed, given the heterogeneity of study designs across the nine clinical questions addressed.
Results: This review proposes a risk-stratified framework for bacteriological sampling in paediatric SA. In children older than 4 years, in whom S. aureus predominates (33–37% of confirmed European cases), arthrocentesis under general anaesthesia with culture, antibiogram, and toxin profiling (PVL, TSST-1) remains the standard of care. In children younger than 4 years with a positive oropharyngeal K. kingae PCR and a stable clinical presentation, non-invasive confirmation may be sufficient, although this strategy depends on a cluster of concordant clinical, biological, and molecular findings rather than the PCR result alone—given a 10–12% asymptomatic carriage rate and the limited reliability of the Kocher–Caird criteria in this age group (only 6.5% of children with confirmed K. kingae hip SA met all four Kocher criteria in the multicentre cohort by De Marco et al.). In severely ill children of any age, comprehensive sampling with planned joint lavage is recommended from the outset. Culture-negative SA (30–60% of cases) is generally associated with a favourable prognosis under empirical treatment.
Conclusion: The dual diagnostic and therapeutic value of joint aspiration justifies systematic bacteriological sampling in paediatric SA, with the sampling modality tailored to age-dependent epidemiology, oropharyngeal PCR results, and clinical severity. This risk-stratified framework requires prospective multicentre validation prior to clinical implementation.
