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Published on: December 3, 2017
Molecular diagnosis of Kingella kingae osteoarticular infections by specific real-time PCR assay
Abdessalam Cherkaoui1, Dimitri Ceroni2, Stéphane Emonet1
1Clinical Microbiology Laboratory, Service of Infectious Diseases, University of Geneva Hospitals (HUG), CH-1211 Geneva 14, Switzerland.
Abstract:
Kingella kingae is an emerging pathogen that is recognized as a causative agent of septic arthritis and osteomyelitis, primarily in infants and children. The bacterium is best detected by rapid inoculation in blood culture systems or by real-time PCR assays. Pathogenesis of the agent was linked recently to the production of a potent cytotoxin, known as RTX, which is toxic to a variety of human cell types. The locus encoding the RTX toxin is thought to be a putative virulence factor, and is, apparently, essential for inducing cytotoxic effects on respiratory epithelial, synovial and macrophage-like cells. Herein, we describe a novel real-time PCR assay that targets the RTX toxin gene and illustrate its use in two clinical cases. The assay exhibited a sensitivity of 30 c.f.u., which is 10-fold more sensitive than a previously published semi-nested broad-range 16S rRNA gene PCR, and showed no cross-reactivity with several related species and common osteoarticular pathogens.
Insights
Kingella kingae, a cause of pediatric bone infections, is detected using a new real-time PCR assay targeting its RTX toxin gene. This highly sensitive method improves early diagnosis of septic arthritis and osteomyelitis.
Area of Science:
- Microbiology
- Molecular Biology
- Pediatric Infectious Diseases
Background:
- Kingella kingae is an emerging pathogen causing septic arthritis and osteomyelitis in children.
- Detection relies on blood cultures or PCR, with pathogenesis linked to a potent RTX cytotoxin.
Observation:
- A novel real-time PCR assay targeting the RTX toxin gene was developed.
- The assay's sensitivity was 30 c.f.u., surpassing existing 16S rRNA gene PCR methods.
- No cross-reactivity was observed with related species or common osteoarticular pathogens.
Findings:
- The RTX toxin gene locus is a putative virulence factor essential for K. kingae's cytotoxic effects.
- The new real-time PCR assay demonstrates high sensitivity and specificity for K. kingae detection.
- Clinical utility was illustrated in two pediatric cases.
Implications:
- This assay offers a more sensitive and specific diagnostic tool for K. kingae infections.
- Improved detection can lead to earlier diagnosis and treatment of pediatric septic arthritis and osteomyelitis.
- Understanding the RTX toxin's role enhances knowledge of K. kingae pathogenesis.
