Kingella kingae septic arthritis

Multicenter evaluation of the BIOFIRE Joint Infection Panel for the detection of bacteria, yeast, and AMR genes in synovial fluid samples

The bioMérieux BIOFIRE Joint Infection (JI) Panel is a multiplex in vitro diagnostic test for the simultaneous and rapid (~1 h) detection of 39 potential pathogens and antimicrobial resistance (AMR) genes directly from synovial fluid (SF) samples. Thirty-one species or groups of microorganisms are included in the kit, as well as several AMR genes. This study, performed to evaluate the BIOFIRE JI Panel for regulatory clearance, provides data from a multicenter evaluation of 1,544 prospectively collected residual SF samples with performance compared to standard-of-care (SOC) culture for organisms or polymerase chain reaction (PCR) and sequencing for AMR genes. The BIOFIRE JI Panel demonstrated a sensitivity of 90.9% or greater for all but six organisms and a positive percent agreement (PPA) of 100% for all AMR genes. The BIOFIRE JI Panel demonstrated a specificity of 98.5% or greater for detection of all organisms and a negative percent agreement (NPA) of 95.7% or greater for all AMR genes. The BIOFIRE JI Panel provides an improvement over SOC culture, with a substantially shorter time to result for both organisms and AMR genes with excellent sensitivity/PPA and specificity/NPA, and is anticipated to provide timely and actionable diagnostic information for joint infections in a variety of clinical scenarios.

Late-Presenting Septic Arthritis of the Hip in Children: Variations in Presentation and a Review of 25 Hips After Surgical Debridement

INTRODUCTION

The septic arthritis of the hip (SAH) is one of the most common musculoskeletal infections occurring in pediatric populations requiring urgent intervention. This study discusses the myriad of clinical and radiological presentations of late-presenting SAH in children and the outcomes of surgical management.

METHODS

After ethical approval, we did retrospective reviews of children treated for late-presenting SAH (after five days of symptoms). We excluded late cases with established sequelae. We recorded age, duration of symptoms, clinical evaluation, and radiographs. We evaluated the final results clinically and radiologically.

RESULTS

Twenty-four patients with 25 hips were eligible for evaluation. At presentation, all had decreased or painful hip movements, but none had a fever. Radiographs revealed the following changes: hip dislocation (four), capital femoral slip (seven), proximal femur/neck osteomyelitis (six), pathological fractured neck femur (two), iliac osteomyelitis (two), and early arthritic changes (two). Hip arthrotomy was done in all cases. Frank pus was found in 21 (84%) cases. Cases with capital slip and fractured neck femur required fixation with two smooth K-wires. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated in three patients and tuberculosis in two cases. Clinical outcomes showed 14 patients with poor outcomes, eight with fair, and two with good. Avascular necrosis (AVN) of the femoral head was noted in 14 hips and complete femoral head resorption in nine.

CONCLUSIONS

The late-presenting SAH in children has a myriad of presentations including dislocation and capital slip with unsatisfactory outcome. However, ongoing local infective processes may necessitate debridement. With limited salvage options available at the sequelae stage, awareness and training for early diagnosis and treatment may be the best way to improve the scenario. We recommend future multicenter randomized studies of predictive factors and indications of arthrotomy in late presenters.

[Septic arthritis and transient synovitis of the hip]

CLINICAL/METHODICAL ISSUE

Differentiating between septic arthritis and transient synovitis can be challenging but is very important as a late diagnosis of septic arthritis can lead to sepsis and joint damage. For correct diagnosis and prediction of complications, the right combination of physical examination, laboratory and radiological studies is needed.

STANDARD RADIOLOGICAL METHODS

Hip ultrasound is easy to learn and has a high sensitivity for joint effusion. Faster diagnosis and therapy are possible due to increasing use of ultrasound. Magnetic resonance imaging (MRI) is primarily used to rule out co-infections (osteomyelitis, pyomyositis) and differential diagnoses. X‑ray is typically nonremarkable in septic arthritis.

PRACTICAL RECOMMENDATIONS

Routine use of ultrasound in nontraumatic pediatric hip pain. Generous use of MRI in case of elevated inflammatory markers or inconclusive clinical findings. Using only few sequences may be appropriate to avoid sedation, primarily fluid sensitive sequences (fat-saturated T2, TIRM, STIR), in case of positive findings, accompanied by T1-weighted images.

Oral Versus Intravenous Antibiotics for Pediatric Osteoarticular Infection: When and to Whom?

BACKGROUND

Osteoarticular infections (OAIs) are typically treated initially with intravenous antibiotics. The objective of this study was to evaluate whether an exclusive oral treatment in selected children may be appropriate.

METHODS

The Spanish Network of Osteoarticular Infections is a nationwide multicenter registry comprising 37 hospitals in Spain. The registry prospectively includes clinical characteristics and outcome of children with OAI. One of the hospitals from RioPed offers oral treatment to children meeting certain criteria. Patients were classified into 2 groups. Group 1: management with initial intravenous antibiotic therapy. Group 2: patients exclusively treated with oral antibiotics. A comparison between the 2 groups was performed.

RESULTS

We compared 893 children who initially received intravenous antibiotics (group 1) with 64 children who received exclusively oral therapy (group 2). Patients from group 2 were younger (33.9 vs. 20.3 months; P = 0.001), had a lower percentage of Staphylococcus aureus (23.3% vs. 3.1%; P < 0.001), a higher proportion of Kingella kingae (12.1% vs. 28.1%; P = 0.001), higher erythrocyte sedimentation rate/C-reactive protein (CRP) ratio (1.4 interquartile range 0.6-3.6 vs. 3.3 interquartile range 1.7-5.7; P < 0.001) and showed lower rate of fever (63% vs. 48.8%; P = 0.024) than in group 1. Complications were not found in group 2.

CONCLUSIONS

An exclusively oral administration could be a safe option in selected patients with OAI. Low-risk criteria are proposed: good general condition, no underlying disease, 6 months to 3 years old, appropriate oral tolerance, C-reactive protein <80 mg/L, erythrocyte sedimentation rate/C-reactive protein ratio ≥0.67, no skin injury, no recent surgery, no cervical spondylodiscitis and no local complications at onset.

Changing aetiology of paediatric septic arthritis

The management of septic arthritis in children requires the prompt administration of antibiotic therapy and the identification of the causative pathogen. In the past, Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae and Haemophilus influenzae type b were considered the main causative agents of the disease, but a substantial fraction of presumptive joint infections remained unconfirmed by conventional bacteriologic cultures. In the last two decades, our knowledge of the aetiology of paediatric infectious arthritis has substantially changed as the result of the implementation of vaccination programmes against H. influenzae type b and pneumococci, and by the use of improved detection methods. In 1988, the inoculation of synovial fluid aspirates into blood culture vials revealed that Kingella kingae, a commensal member of the oropharyngeal microbiota, was the prime aetiology of skeletal system infections in children aged 6-48 months. The clinical presentation of K. kingae arthritis is subtle, and the disease is frequently missed by classic clinical and laboratory diagnostic criteria. Many children are afebrile, the acute phase reactants levels and the white blood cell counts in the blood and synovial fluid specimens are frequently normal, requiring a high clinical acumen. Increasing use of sensitive molecular methods in recent years, and particularly nucleic acid amplification tests that target K. kingae-specific genes, has further improved the detection of this elusive pathogen, demonstrated that it is responsible for 30-93% of all cases of septic arthritis below 4 years of age and reduced the fraction of culture-negative infections.