High positivity of blood cultures obtained within two hours after shaking chills

OBJECTIVE: To determine whether the time lag between blood culture draw and the start of shaking chills is associated with blood culture positivity. METHODS: A prospective observational study was undertaken from January 2013 to March 2015 at a referral center in Okinawa, Japan. All enrolled patients were adults with an episode of shaking chills who were newly admitted to the division of infectious diseases. The study exposure was the time lag between blood culture draw and the most recent episode of shaking chills. RESULTS: Among patients whose blood cultures were obtained within 2h after shaking chills started, the blood culture positivity was 53.6% (52/97), whereas among patients whose blood cultures were obtained after more than 2h, the positivity was 37.6% (44/117) (p=0.019). The adjusted odds ratio of blood culture positivity for samples drawn within 2h after shaking chills was 1.88 (95% confidence interval 1.01-3.51, p=0.046). Escherichia coli were the most frequently detected bacteria (58/105). CONCLUSIONS: The positivity of blood cultures obtained within 2h after the start of the most recent shaking chills was higher than that for blood cultures obtained after 2h.