Laboratory of Medical Microbiology, Antwerp University Hospital, Drie Eikenstraat 655, 2650, Edegem, Belgium.
University of Antwerp, Edegem, Belgium.
Eur J Clin Microbiol Infect Dis. 2022 Oct;41(10):1263-1268. doi: 10.1007/s10096-022-04487-4. Epub 2022 Sep 6.
Staphylococcus aureus bacteremia (SAB) is a relevant finding which prompts a thorough diagnostic work-up. Follow-up blood cultures (BC) are essential in this work-up. We investigate the probability of detecting an ongoing bacteremia after initiation of active therapy according to the number of BC taken at key time points. A retrospective analysis of all patients with SAB in a 6-year period was performed. Total number of BCs taken and the positivity was registered for each day after start of therapy. A positivity-rate was corrected using a logistic mixed effects model. Observed detection frequencies were applied to calculate detection probabilities using binomial distributions. Three hundred and seventeen cases were withheld for analysis. A BC bottle positivity rate of 66.7% was found 1 day after initiation of active therapy, which decreased to 48.5% on day 4. When using 1 set of FU-BC, 73.4% of persisting SABs are detected. To maintain a probability of detection of ≥ 90%, 2 BC sets should be taken on day 2 and day 4 after start of therapy. In 10 of 109 patients with positive FU-BC, skip phenomena were registered, with a significant higher proportion in patients with < 4 BC bottles taken (14%) than when ≥ 4 BC bottles were taken (4.1%). We recommend taking 2 BC sets on days 2 and 4 after start of therapy in order to detect ≥ 90% of persisting SABs, limiting skip phenomena and blood volume required. We strongly advice against taking a single BC set as follow-up for SAB.
金黄色葡萄球菌菌血症 (SAB) 是一个重要的发现，提示需要进行全面的诊断性检查。在这项检查中，后续血培养 (BC) 至关重要。我们根据在关键时间点采集的 BC 数量，研究在开始积极治疗后检测持续菌血症的可能性。对 6 年内所有 SAB 患者进行了回顾性分析。记录了每个治疗后天数采集的 BC 总数和阳性率。使用逻辑混合效应模型校正阳性率。使用二项式分布，应用观察到的检测频率计算检测概率。排除了 317 例病例进行分析。在开始积极治疗 1 天后，BC 瓶的阳性率为 66.7%，第 4 天降至 48.5%。当使用 1 套 FU-BC 时，73.4%的持续 SAB 被检测到。为了保持检测概率≥90%，应在开始治疗后第 2 天和第 4 天采集 2 套 BC。在 109 例 FU-BC 阳性患者中，有 10 例出现了跳过现象，采集的 BC 瓶数<4 瓶的患者中跳过现象的比例明显高于采集的 BC 瓶数≥4 瓶的患者（14%比 4.1%）。我们建议在开始治疗后第 2 天和第 4 天采集 2 套 BC，以检测到≥90%的持续 SAB，减少跳过现象和所需的血量。我们强烈建议不要仅采集 1 套 BC 作为 SAB 的随访。
