First report of Kingella kingae diagnosed in pediatric bone and joint infections in Morocco.

BACKGROUND

The progress of diagnostic strategies and molecular methods improved the detection of Kingella kingae in bone and joint infections, and now, Kingella kingae is being increasingly recognized as the most frequent cause of bone and joint infection BJI in early childhood. The main objective of this prospective study is to report the frequency of Kingella Kingae in negative culture bone and joint pediatric infections, and to describe the clinical and biologic features of these children.

METHODS

From December 2016 to June 2019, we selected all hospitalized patients with suspected BJI. When culture was negative on the fifth day, children under 10 years were subsequently included in the study, and PCR assay was performed systematically for researching K. kingae specific gene cpn60. Microbial culture and identification were made using standard bacteriological methods. The demographics, clinical, laboratory, radiographic and clinical features were reviewed from medical records.

RESULTS

We enrolled 65 children with culture negative BJI, 46 of them having under 10 years old have been screened for the cpn60 gene. Thus, the gene encoding Kingella kingae was positive for 27 BJI cases (58.7%). The mean age of children was 3.02 years, 55.6% were aged 6 months-4 years and 29.6% of them were aged 5-10 years. The male to female ratio was 1.7 and 16 cases (59.26%) occurred during the fall-winter period. The most frequent BJI type was septic arthritis (77.8%) and the most affected sites were knee (51.9%) and hip (37.0%). We recorded a mild clinical picture with normal to mildly raised inflammatory markers. All patients had good clinical and functional outcomes, with no serious orthopedic sequelae..

CONCLUSION

K kingae is an important pathogen of culture-negative BJI in Moroccan children. PCR testing should be performed in culture-negative cases of children not only in the typical age range of 6 months to 4 years. When implemented in the routine clinical microbiology laboratory, a specific K. kingae PCR assay can provide a better diagnostic performance of BJI.