Rate of blood culture submissions in Japan as an indicator of bloodstream infections.

Bloodstream infections can be missed if blood cultures are not submitted properly. We therefore examined the optimal number of blood cultures submitted to provide an indicator of the incidence of bloodstream infections in Japan. We analysed the number of blood cultures submitted per 1000 patient days as an indicator of the incidence of bloodstream infections, using data on blood cultures from 117 acute care hospitals in Japan. Kruskal-Wallis and Dunn tests were used to determine plateau numbers of blood cultures submitted per 1000 patient days. The median number of blood culture sets per 1000 patient days was 26.2, the median rate of solitary blood culture submissions was 8.0%, the median contamination rate was 1.3%, the median positivity rate including contaminants was 13.4%, and the median incidence of bloodstream infections per 1000 patient days was 2.8. The incidence of detected bloodstream infections increased with increasing blood culture submissions up to plateau around 45 submissions per 1000 patient days. In acute care hospitals in Japan, the incidence of BSI increased as the rate of blood culture submissions increased, but the positivity rate may reach a plateau at about 45 submissions per 1000 patient days, and this might be an indicator for the optimal number of blood culture submission in Japan.