Vincent Paoli MD, Presenter: Nothing to Disclose

Chaker Marc, Abstract Co-Author: Nothing to Disclose

Anne-Marie Freydiere, Abstract Co-Author: Nothing to Disclose

Jerome Berard, Abstract Co-Author: Nothing to Disclose

Jean-Pierre Pracros, Abstract Co-Author: Nothing to Disclose

Kingella kingae is rising as a major etiologic agent in osteo-articular infection (OAI) of very young children. Recent advances in PCR bacteriological diagnosis have increased its prevalence (up to 45%), more than Staphylococcus aureus (24%) and usual bacterias. If such results have to be moderated, it cannot be denied that this bacterium has a growing interest in a daily paediatric practice. Clinical presentation is slightly different from other bacteria with a less virulent beginning  and only mild symptoms. Therefore, this study was designed to assess magnetic resonance imaging features in differentiating K. kingae OAI from other pyogenic OAI.

MR imaging findings in 24 children with proved K. kingae OAI were compared with those of 24 children with S. aureus OAI, considering this bacteria representative for pyogenic OAI. MR imaging evaluated parameters were : length of bone oedema (mm), adjacent soft tissue damages (inflammation, effusion or abscess), subperiosteal abscess, intra osseous bone abscess and its association with a rim of sclerosis or not.

Bone oedema is less spread in K. kingae OAI (12,9 mm) than in S. aureus ones (49,6 mm) (p<0,01). Soft tissue analyse (inflammation, effusion, abscess) is unable to help in the discrimination of the micro organisms. Subperiosteal abscess occurs less frequently with K. kingae 8% (n=2), than with S. aureus, 42%, (p=0,017). Presence of a bone abscess is not discriminatory : 46% of K. kingae OAI (n=8) versus 33% of S. aureus ones (n=11), (p=0,093). It becomes significant when considering its association with a rim of sclerosis : 42% of K. kingae OIA (n=10), never found with S. aureus (p<0,01).

MR imaging provides useful information in order to differentiate K.kingae OIA from other pyogenic OAI. Highlighted signs are not specific but demonstrative for a slow infectious process, in agreement with already known clinical and biological features of K. kingae OAI.

If both clinical background and MR Imaging findings are demonstrative for a K. kingae infectious origin, adapted antibiotherapy may be started before obtaining the bacteriological results.

Paoli, V, Marc, C, Freydiere, A, Berard, J, Pracros, J, MR Imaging Findings in Kingella Kingae Osteo-articular Infections in Children.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8012646.html