New research presented at IDWeek 2025 in Atlanta found that polymerase chain reaction (PCR) testing substantially increased bacterial detection in children under 5 years old with bone and joint infections (BJI), though the findings suggest limited influence on treatment selection or clinical outcomes.
The single-center, multi-site retrospective cohort study evaluated 168 pediatric patients admitted with bone or joint infections between January 2015 and April 2024 in Central Texas. Researchers compared cases among children younger than 5 years with those 5 years and older to determine the diagnostic and clinical value of molecular testing.
Traditional cultures identified bacteria in 37% of children under 5 years, compared with 62.1% of older children. When PCR testing was added, identification rates rose to 54.3% and 64.4%, respectively. The most common pathogens were Staphylococcus aureus and Kingella kingae, the latter of which is particularly prevalent in preschool-aged patients, according to the investigators.
The poster authors emphasized that PCR testing offered a clear diagnostic benefit for detecting K. kingae, improving accuracy in cases that might otherwise remain undiagnosed.
Despite improved organism identification, antibiotic prescribing patterns remained consistent across groups. Most children were discharged on either amoxicillin/clavulanate or cephalexin, regardless of whether a pathogen was confirmed by culture or PCR. Clinicians more frequently prescribed amoxicillin/clavulanate for children under 5 years with negative cultures, reflecting coverage considerations for K. kingae.
One patient with methicillin-susceptible S. aureus infection treated with cephalexin required readmission for treatment failure, though this represented an isolated case. Overall, researchers found no strong evidence that positive molecular results led to changes in antibiotic choice or improved outcomes.
Key findings from the study
The authors concluded that PCR testing meaningfully enhances diagnostic yield in younger children but that its clinical utility—beyond organism detection—remains uncertain.
"Further research is warranted to assess the clinical benefit of PCR testing in pediatric BJI, where its impact on clinical outcomes remains uncertain," the investigative team concluded.
Reference:
Wesolowski A, et al. Age-Dependent Diagnostic Yield and Treatment in Pediatric Bone and Joint Infections. Poster. Presented at IDWeek 2025. October 19-22, 2025. Atlanta, GA.
