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[Septic arthritis in two young children caused by unusual gram-negative pathogens]
J Bruijn1, J Verhage, R W Bosboom
1Afd. Kindergeneeskunde, Ziekenhuis Rijnstate, TA Arnhem.
Insights
Septic arthritis in young children can present with mild symptoms. Unusual Gram-negative bacteria like Kingella kingae and Moraxella can cause septic arthritis and may be detected using aerobic blood culture systems.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Septic arthritis in young children often presents with subtle symptoms and ambiguous laboratory results.
- Gram-negative bacteria are uncommon causes of septic arthritis and are challenging to identify via standard Gram staining.
- Early diagnosis and treatment are crucial to prevent joint damage and long-term complications.
Observation:
- Two children, a 2-year-old girl and a 10-month-old boy, presented with moderate knee inflammation.
- The girl had Gram-positive cocci on synovial fluid Gram stain, yielding Kingella kingae, while the boy's synovial fluid culture grew Moraxella.
- Both children had preceding pharyngitis; the boy also had paronychia.
Findings:
- Kingella kingae and Moraxella, both Gram-negative bacteria, were identified as causative agents of septic arthritis in these children.
- The Gram stain of synovial fluid was not fully indicative of the causative pathogen in either case.
- Aerobic blood culture systems successfully isolated the difficult-to-detect microorganisms.
Implications:
- This case highlights the importance of considering unusual pathogens in pediatric septic arthritis, even with non-specific initial findings.
- Utilizing aerobic blood culture systems can improve the detection rates of rare bacteria in joint fluid.
- Prompt antibiotic therapy led to complete recovery without sequelae, emphasizing the need for timely and accurate diagnosis.
Abstract:
Two children, a girl aged 2 years and a boy aged 10 months, were moderately ill with signs of inflammation of the left and the right knee, respectively. Both had had pharyngitis, and the boy also had paronychia of the right foot. The Gram preparation of synovial fluid showed Gram-positive cocci in the girl, while Kingella kingae was cultured. In the boy, a Moraxella was cultured from the synovial fluid using an aerobic blood culture system. Both recovered without sequelae after adequate antibiotic treatment. The micro-organisms cultured were Gram-negative bacteria, which are rarely seen in septic arthritis and are difficult to demonstrate. In young children, septic arthritis often presents with mild symptoms and inconclusive laboratory findings. Even if the Gram preparation of the synovial fluid shows no micro-organisms, unusual pathogens may be isolated by means of an aerobic blood culture system.