[Osteomyelitis: a probable, uncommon etiology agent].

Area of Science:

• Pediatric Rheumatology
• Pediatric Infectious Diseases
• Pediatric Orthopedic Infections

Background:

• Septic arthritis accounts for 6.5% of childhood arthritides, often arising from hematogenous spread or direct extension of infection.
• Commonly implicated bacteria include Staphylococcus aureus and streptococci, but Kingella kingae is increasingly recognized in children under four.
• Systemic signs like fever and bone pain, alongside local tenderness, often indicate septic arthritis.

Observation:

• Kingella kingae infections in children typically present with subtle clinical signs and mild inflammatory responses.
• Affected children may exhibit few overt signs of osteoarticular infection, complicating diagnosis.
• Early Magnetic Resonance Imaging (MRI) is crucial for distinguishing K. kingae from Gram-positive cocci in osteoarticular infections.

Findings:

• Cartilaginous involvement and modest soft tissue/bone reactions on MRI suggest K. kingae.
• The subtle presentation of K. kingae necessitates its inclusion in the differential diagnosis for pediatric osteoarticular infections.
• This report details an unusual case of osteomyelitis with clinical and MRI findings suggestive of K. kingae.

Implications:

• Recognizing the subtle presentation of Kingella kingae is vital for timely diagnosis and treatment of pediatric septic arthritis.
• Advanced imaging like MRI plays a key role in differentiating K. kingae from other pathogens in children.
• This highlights the importance of considering emerging pathogens in the differential diagnosis of pediatric bone and joint infections.