Dimitri Ceroni

Detection of Kingella kingae Osteoarticular Infections in Children by Oropharyngeal Swab PCR

OBJECTIVE: The purpose of this study was to investigate if oropharyngeal swab polymerase chain reaction (PCR) could predict osteoarticular infection (OAI) due to Kingella kingae in young children. METHODS: One hundred twenty-three consecutive children aged 6 to 48 months presenting with atraumatic osteoarticular complaints were prospectively studied. All had a clinical evaluation, imaging, and blood samples. Blood and oropharyngeal specimens were tested with a PCR assay specific for K kingae. OAI was defined as bone, joint, or blood detection of pathogenic bacteria, or MRI consistent with infection in the absence of positive microbiology. K kingae OAI was defined by blood, bone, or synovial fluid positivity for the organism by culture or PCR. RESULTS: Forty children met the OAI case definition; 30 had K kingae OAI, 1 had another organism, and 9 had no microbiologic diagnosis. All 30 oropharyngeal swabs from the K kingae case patients and 8 swabs from the 84 patients without OAI or with OAI caused by another organism were positive. The sensitivity and specificity of the oropharyngeal swab PCR assay for K kingae were 100% and 90.5%, respectively. CONCLUSIONS: Detection of K kingae DNA in oropharyngeal swabs of children with clinical findings of OAI is predictive of K kingae OAI. If these findings are replicated in other settings, detection of K kingae by oropharyngeal swab PCR could improve the recognition of OAI.

Small risk of osteoarticular infections in children with asymptomatic oropharyngeal carriage of Kingella kingae.

The aim of this study was to evaluate the absolute risk for children younger than 4 years of age with asymptomatic oropharyngeal carriage of Kingella kingae to sustain an osteoarticular infection. The rate of K. kingae carriage in the oropharyngeal mucosa was 9% among healthy children, and the risk for an asymptomatic carrier to develop an osteoarticular infection due to K. Kingae was estimated to be lower than 1%.

Effects of Cast-Mediated Immobilization on Bone Mineral Mass at Various Sites in Adolescents with Lower-Extremity Fracture

BACKGROUNDnLeg or ankle fractures occur commonly in the pediatric population and are primarily treated with closed reduction and cast immobilization. The most predictable consequences of immobilization and subsequent weight-bearing restriction are loss of bone mineral mass, substantial muscle atrophy, and functional limitations. The purposes of this study were to determine if lower-limb fractures in adolescents are associated with abnormal bone mineral density or content at the time of fracture, and to quantify bone mineral loss at various sites due to cast-mediated immobilization and limited weight-bearing.nnnMETHODSnWe recruited fifty adolescents aged ten to sixteen years who had undergone cast immobilization for a leg or ankle fracture. Dual x-ray absorptiometry scans of the total body, lumbar spine, hip, leg, and calcaneus were performed at the time of fracture and at cast removal. Patients with a fracture were paired with healthy controls according to sex and age. Values at baseline and at cast removal, or at equivalent time intervals in the control group, were compared between groups and between the injured and uninjured legs of the adolescents with the fracture.nnnRESULTSnAt the time of fracture, there were no observed differences in the bone mineral density or bone mineral content Z-scores of the total body or the lumbar spine, or in the bone mineral density Z-scores of the calcaneus, between the injured and healthy subjects. At cast removal, bone mineral parameters on the injured side were significantly lower than those on the uninjured side in the injured group. Differences ranged from -5.8% to -31.7% for bone mineral density and from -5.2% to -19.4% for bone mineral content. During the cast period, the injured adolescents had a significant decrease of bone mineral density at the hip, greater trochanter, calcaneus, and total lower limb as compared with the healthy controls.nnnCONCLUSIONSnLower-limb fractures are not related to osteopenia in adolescents at the time of fracture. However, osteopenia does develop in the injured limb during cast immobilization for fracture treatment. Further investigation is required to determine if the bone mineral mass will return to normal or if a permanent decrease is to be expected, which may constitute a hypothetical risk of sustaining a second fracture.

Unusually severe cases of Kingella kingae osteoarticular infections in children

Backgrounds: With the development of molecular biology and specific polymerase chain reaction, Kingella kingae has become the primary diagnosis of osteoarticular infections in young children. Clinical features of these osteoarticular infections are typically mild, and outcome is almost always favorable. We report a series of unusually severe cases of K. kingae osteoarticular infections. Methods: All patients with severe osteoarticular infections at presentation were reviewed retrospectively in 2 European pediatric centers. K. kingae was identified using real-time polymerase chain reaction in blood, fluid joint or osseous samples. Clinical, laboratory tests and radiographic data during hospitalization and follow-up were analyzed. Results: Ten children (mean age 21u2009±u200912 months) with severe osteoarticular infections caused by K. kingae were identified between 2008 and 2011. Diagnostic delay averaged 13.2u2009±u20098 days. Only 1 patient was febrile at admission, and 50% children had normal C-reactive protein values (⩽10u2009mg/dL) at presentation. Surgical treatment was performed in all cases. Intravenous antibiotic therapy by cephalosporins for an average of 8u2009±u20096 days was followed by oral treatment for 27u2009±u20096 days. Mean follow-up was 24.8u2009±u20099 months, and satisfactory outcomes were reported in all cases. Two patients (20%) developed a central epiphysiodesis of the proximal humerus during follow-up, but without significant clinical consequence for the moment. Conclusions: Because of their mild clinical features at onset, diagnosis of K. kingae osteoarticular infections can be delayed. Care should be taken for early detection and treatment of these infections because bony lytic lesions and potentially definitive growth cartilage damage can occur.

Occupational and patient exposure as well as image quality for full spine examinations with the EOS imaging system

PURPOSEnEOS (EOS imaging S.A, Paris, France) is an x-ray imaging system that uses slot-scanning technology in order to optimize the trade-off between image quality and dose. The goal of this study was to characterize the EOS system in terms of occupational exposure, organ doses to patients as well as image quality for full spine examinations.nnnMETHODSnOccupational exposure was determined by measuring the ambient dose equivalents in the radiological room during a standard full spine examination. The patient dosimetry was performed using anthropomorphic phantoms representing an adolescent and a five-year-old child. The organ doses were measured with thermoluminescent detectors and then used to calculate effective doses. Patient exposure with EOS was then compared to dose levels reported for conventional radiological systems. Image quality was assessed in terms of spatial resolution and different noise contributions to evaluate the detectors performances of the system. The spatial-frequency signal transfer efficiency of the imaging system was quantified by the detective quantum efficiency (DQE).nnnRESULTSnThe use of a protective apron when the medical staff or parents have to stand near to the cubicle in the radiological room is recommended. The estimated effective dose to patients undergoing a full spine examination with the EOS system was 290 μSv for an adult and 200 μSv for a child. MTF and NPS are nonisotropic, with higher values in the scanning direction; they are in addition energy-dependent, but scanning speed independent. The system was shown to be quantum-limited, with a maximum DQE of 13%. The relevance of the DQE for slot-scanning system has been addressed.nnnCONCLUSIONSnAs a summary, the estimated effective dose was 290 μSv for an adult; the image quality remains comparable to conventional systems.

Possible association of Kingella kingae with infantile spondylodiscitis.

The course of the spondylodiscitis’ infantile form is characterized by a mild-to-moderate clinical and biologic inflammatory response. Unfortunately, blood and disk/vertebral aspiration cultures show a high percentage of negative results. However, detecting Kingella kingae DNA in the oropharynx provided reasonable suspicion, to our opinion, that this microorganism is responsible for the spondylodiscitis.

Osteoarticular infections in young children: what has changed over the last years?

Osteoarticular infections remain a significant cause of morbidity worldwide in young children. They can have a devastating impact with a high rate of serious and long-lasting sequelae, especially on remaining growth. Depending on the localisation of infection, they manifest as osteomyelitis, septic arthritis, a combination of both (i.e., osteomyelitis with adjacent septic arthritis) or spondylodiscitis. Osteoarticular infections can be divided into three types according to the source of infection: haematogenous; secondary to contiguous infection; or secondary to direct inoculation. During the last few years, many principles regarding diagnostic assays and the microbiological causes of these infections have evolved in a significant manner. In the present current-opinion review, we discuss recent concepts regarding epidemiology, physiopathology, and the microbiology of bone and joint infections in young children, as well as clinical presentations, diagnosis, and treatment of these infections. Clinicians caring for children need to be especially well versed in these newer concepts as they can be used to guide evaluation and treatment.

Bilateral and gender differences during single-legged vertical jump performance in healthy teenagers.

Ceroni, D, Martin, XE, Delhumeau, C, and Farpour-Lambert, NJ. Bilateral and gender differences during single-legged vertical jump performance in healthy teenagers. J Strength Cond Res 26(2): 452–457, 2012—The determination of physiologic lower limb functional imbalance among healthy teenagers is important to follow the rehabilitation progress and return to normal activity of injured subjects. We investigated the differences in vertical jump capacity between both legs in a group of healthy boys and girls, considering the performances in the dominant vs. non-dominant, and in the most vs. least efficient leg. Strength and power performances were compared in 117 boys and 106 girls aged 10–16 years during a single-leg vertical countermovement jump (SLVCJ) test. When leg dominance was defined subjectively by the participant, no difference was noted between the 2 legs. Statistically significant differences were recorded between the most and less efficient leg in strength and power performances for both genders. Girls had significantly greater peak strength than did age-matched boys, but boys showed significant increases in maximal power outputs compared with that shown by age-matched girls. When the results were analyzed according to the percentage of participants falling within certain bands of limb asymmetry, approximately 20–30% showed a difference of >15% between the 2 limbs without any relation to gender. Subjective expression of leg dominance cannot be used as a predictor of SLVCJ performance. Differences of <15% in SLVCJ performance between both legs should be considered as the physiological norm in this age group. A greater appreciation of the potential diagnostic value of the SLVCJ test may be obtained if the results are interpreted in terms of the percentage of subjects falling within certain bands of limb asymmetry. Gender-based differences in the SLVCJ test vary and depend upon whether the results are interpreted in terms of strength or power output.

COMPARING THE OROPHARYNGEAL COLONIZATION DENSITY OF KINGELLA KINGAE BETWEEN ASYMPTOMATIC CARRIERS AND CHILDREN WITH INVASIVE OSTEOARTICULAR INFECTIONS

Colonization of the oropharynx by Kingella kingae is currently considered to be a prerequisite for later development of invasive infections. However, the oropharyngeal K. kingae DNA bacterial load in children with osteoarticular infections caused by this microorganism is not different than that of asymptomatic carriers.

30 years of study of Kingella kingae: post tenebras, lux

Kingella kingae is a Gram-negative bacterium that is today recognized as the major cause of joint and bone infections in young children. This microorganism is a member of the normal flora of the oropharynx, and the carriage rate among children under 4 years of age is approximately 10%. K. kingae is transmitted from child to child through close personal contact. Key virulence factors of K. kingae include expression of type IV pili, Knh-mediated adhesive activity and production of a potent RTX toxin. The clinical presentation of K. kingae invasive infection is often subtle and may be associated to mild-to-moderate biologic inflammatory responses, highlighting the importance a high index of suspicion. Molecular diagnosis of K. kingae infections by nucleic acid amplification techniques enables identification of this fastidious microorganism. Invasive infections typically respond favorably to medical treatment, with the exception of cases of endocarditis, which may require urgent valve replacement.