Kingella kingae is an emerging pathogen that may be recognized as the most common bacteria responsible for osteoarticular infections (OAI) in young children. However, its diagnosis remains a challenge and thus little evoked in infants, because K. kingae is a difficult germ to isolate on solid medium, and clinical signs are often mild. The main objective of this prospective study is to describe the clinical, biologic, and radiologic features of children with OAI caused by K. kingae. In addition, we describe the usage of a new specific real-time PCR assay in children under 4 years admitted for OAI with a probe that detects 2 independent gene targets from the K. kingae RTX toxin. All children less than 4 years admitted in our institution between January 2007 and November 2009 for suspected OAI were enrolled in this prospective study (43 cases). Age, gender, clinical signs, duration of symptoms, bone or joint involved, imaging studies, and laboratory data, including bacterial investigations, full blood count, erythrocyte sedimentation rate, and serum C-reactive protein were collected for analysis. Identification of the microorganism was possible for 28 cases (65.1%) yielding K. kingae in 23 cases (82.1%). Mean age of children with K. kingae OAI was 19.6 months. Less than 15% of these patients were febrile during the admission, but 46% of them presented a history of fever-peak superior to 38.5 degrees C before admission. Thirty-nine percent of the children with K. kingae OAI had normal C-reactive protein; WBC was elevated in only 2 cases, whereas 21 patients had abnormal erythrocyte sedimentation rate, and 13 abnormal platelet counts. Direct Gram staining and classical isolation methods were negative for all cases subsequently detected as K. kingae OAI by specific real-time PCR. This study confirms that K. kingae is the major bacterial cause of OAI in children less than 4 years. The real-time PCR assay, specific to the K. kingae RTX toxin, provides interesting diagnostic performance when implemented in the routine microbiologic laboratory. Needless to say, a bigger cohort is required to adequately study this new qPCR assay, but the results so far seem promising. The most important additional finding is the mild-to-moderate clinical, radiologic, and biologic inflammatory response to K. kingae infection with the result that these children present few criteria evocative of OAI. II.

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.

Osteoarticular infections caused by Kingella kingae are characterized by mild-to-moderate clinical and biologic inflammatory signs that are different from those caused by Gram-positive cocci. A combined score was built to find the best model to predict K. kingae osteoarticular infections by using the following 4 variables: body temperature <38°C, serum C-reactive protein <55 mg/L, white blood cell count <14,000/mm³, and band forms <150/mm³.

Pin-tract infection (PTI) is the most commonly expected problem, or even an almost inevitable complication, when using external fixation. Left unteated, PTI will progress unavoidably, lead to mechanical pin loosening, and ultimately cause instability of the external fixator pin–bone construct. Thus, PTI remains a clinical challenge, specifically in cases of limb lengthening or deformity correction. Standardised pin site protocols which encompass an understanding of external fixator biomechanics and meticulous surgical technique during pin and wire insertion, postoperative pin site care and pin removal could limit the incidence of major infections and treatment failures. Here we discuss concepts regarding the epidemiology, physiopathology and microbiology of PTI in paediatric populations, as well as the clinical presentations, diagnosis, classification and treatment of these infections.

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.

Background: Primary epiphyseal or apophyseal subacute osteomyelitis (PEASAO) is a rare condition that typically has mild symptoms and lack of a systemic reaction, according to opinions, case reports, and case series. We reviewed fourteen consecutive cases of PEASAO treated at our institution over a thirteen-year period to characterize this disorder. Methods: We retrospectively reviewed the medical records of all children and adolescents who had been surgically managed for PEASAO at our institution from January 2000 to December 2012. A systematic review of the literature was also performed to identify trends in causative organisms and formulate evidence-based recommendations for diagnosis and treatment. Results: Fourteen children (median age, 27.8 months) with PEASAO were included in the study. Fever (rectal temperature, >38°C) was present at admission in two children, C-reactive protein was within the normal range (20 mm/hr in eight, and the white blood-cell count was normal in all. The pathogen was not identified on blood cultures in any child and was identified on classical cultures of bone samples in only one. Use of PCR (polymerase chain reaction) assays allowed the pathogen to be identified in an additional eight children. The pathogen was Kingella kingae in eight and methicillin-sensitive Staphylococcus aureus in one. Discussion: The use of organism-specific real-time PCR assays markedly improves the detection rate of the pathogen responsible for PEASAO, and K. kingae is the most commonly detected pathogen. The literature highlights a biphasic age distribution of PEASAO in children. The infantile form affects children from one to less than four years of age, accounting for approximately 75% of all PEASAO cases. The second form, in older children, is more likely to be associated with fever and systemic symptoms. The femur and the tibia are the most commonly affected long bones. Laboratory data are usually noncontributory for diagnosing PEASAO, and blood cultures are often sterile. Although K. kingae is the most commonly detected microorganism in children less than four years of age, S. aureus is responsible for most PEASAO in older children. Antibiotic treatment is usually sufficient to eradicate the pathogen.