<i>Kingella kingae</i> septic arthritis.

Abstract

The aim of this study was to determine the extent to which patient demographics, clinical presentation, and blood parameters vary in <i>Kingella kingae</i> septic arthritis when compared with those of other organisms, and whether this difference needs to be considered when assessing children in whom a diagnosis of septic arthritis is suspected. A prospective case series was undertaken at a single UK paediatric institution between October 2012 and November 2018 of all patients referred with suspected septic arthritis. We recorded the clinical, biochemical, and microbiological findings in all patients. A total of 160 patients underwent arthrotomy for a presumed septic arthritis. Of these, no organism was identified in 61 and only 25 of these were both culture- and polymerase chain reaction (PCR)-negative. A total of 36 patients did not undergo PCR analysis. Of the remaining 99 culture- and PCR-positive patients, <i>K. kingae</i> was the most commonly isolated organism (42%, n = 42). The knee (n = 21), shoulder (n = 9), and hip (n = 5) were the three most commonly affected joints. A total of 28 cases (66%) of <i>K. kingae</i> infection were detected only on PCR. The mean age of <i>K. kingae-</i>positive cases (16.1 months) was significantly lower than that of those whose septic arthitis was due to other organisms (49.4 months; p < 0.001). The mean CRP was significantly lower in the <i>K. kingae</i> group than in the other organism group (p < 0.001). The mean ESR/CRP ratio was significantly higher in <i>K. kingae</i> (2.84) than in other infections (1.55; p < 0.008). The mean ESR and ESR/CRP were not significantly different from those in the 'no organism identified' group. <i>K. kingae</i> was the most commonly isolated organism from paediatric culture- and/or PCR-positive confirmed septic arthritis, with only one third of cases detected on routine cultures. It is important to develop and maintain a clinical suspicion for <i>K. kingae</i> infection in young patients presenting atypically. Routine PCR testing is recommended in these patients. Cite this article: <i>Bone Joint J</i> 2021;103-B(3):584-588.