Isolation of Kingella kingae from synovial fluids using four commercial blood culture bottles

According to the literature, Kingella kingae may be an underdiagnosed cause of joint and bone infections in children. The use of the Bactec blood culture system for culture of joint fluids has dramatically improved the isolation of this fastidious bacterium. The aim of this study was to test the recovery rate and detection time of four commercial blood culture systems: three different BacT/Alert (Organon Teknika, USA) bottles and one Bactec (Becton Dickinson Microbiology Systems, USA) bottle, all inoculated with Kingella kingae strains mixed with pooled synovial fluids. For each strain the same inoculum and volume of synovial fluid was distributed into each of the four bottles. All 24 strains tested grew in the BacT/Alert Aerobic (100%) and the BacT/Alert Pedi-BacT (100%) bottles. Twenty-one strains grew in the BacT/Alert FAN aerobic (88%) bottle, and 15 strains grew in the Bactec Plus Aerobic F (63%) bottle, in both systems within 12 days (P < 0.01). The Kingella kingae strains were first detected in the BacT/Alert Pedi-BacT bottles (P<0.001). The results were reproducible. The BacT/Alert blood culture bottles were superior to previously described blood culture systems in isolating Kingella kingae from synovial fluid, even with small inoculums and small volumes of synovial fluid.