Department of Internal Medicine, Section Acute Medicine, Amsterdam University Medical Centers, Location VU University Medical Center, Amsterdam, The Netherlands.
Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Location VU University Medical Center and Location Academic Medical Center, Amsterdam, The Netherlands.
PLoS One. 2019 Mar 21;14(3):e0214052. doi: 10.1371/journal.pone.0214052. eCollection 2019.
Blood cultures remain the gold standard for detecting bacteremia despite their limitations. The current practice of blood culture collection is still inefficient with low yields. Limited focus has been given to the association between timing of specimen collection at different time points during admission and their yield.
We carried out a retrospective observational study by analyzing all 3,890 sets of cultures collected from the 1,962 admitted patients over the seven-month period of this study. We compared the blood culture yield between the early group (≤24 hours after admission) and the late group (> 24 hours of admission). We also investigated the effect of prehospital oral antibiotics and pre-analytical time on the first cultures in the emergency department. Epidemiology and efficiency of blood cultures were studied for each medical specialty.
In total, 3,349(86.1%) blood cultures were negative and 541(13.9%) were positive for one or more microorganisms. After correcting for contamination, the overall yield was 290 (7.5%). The early group (n = 1,490) yielded significantly more true-positive cultures (10.1% versus 5.8%, P<0.001) than the late group (n = 2,400). The emergency department had a significantly higher yield than general wards, 11.2% versus 5.7% (p<0.001). Prehospital oral antibiotic use and pre-analytical time did not affect the yield of first cultures at the emergency department (p = 0.735 and 0.816 respectively). The number of tests needed to obtain one true-positive culture varied between departments, ranging from 7 to 45.
This study showed that blood cultures are inefficient in detecting bacteremia. Cultures collected during 24 hours after admission yielded more positive results than those collected later. Significant variations in blood culture epidemiology and efficiency per specialty suggest that guidelines should be reevaluated. Future studies should aim at improving blood culture yield, implementing educational programs to reduce contamination and cost-effective application of modern molecular diagnostic technologies.
尽管存在局限性，血液培养仍然是检测菌血症的金标准。目前的血液培养采集实践仍然效率低下，产量低。人们对在入院期间不同时间点采集标本的时间与产量之间的关系关注有限。
我们通过分析本研究期间 7 个月内 1962 名入院患者的 3890 套培养物进行了回顾性观察研究。我们比较了早期组（入院后≤24 小时）和晚期组（入院后＞24 小时）的血培养产量。我们还调查了院前口服抗生素和分析前时间对急诊科首次培养的影响。研究了每个医学专业的血液培养的流行病学和效率。
共有 3349 份（86.1%）血培养为阴性，541 份（13.9%）为一种或多种微生物阳性。校正污染后，总产率为 290（7.5%）。早期组（n=1490）的真阳性培养物产量明显高于晚期组（n=2400）（10.1%比 5.8%，P<0.001）。急诊科的产量明显高于普通病房，分别为 11.2%和 5.7%（p<0.001）。院前口服抗生素的使用和分析前时间对急诊科首次培养的产量没有影响（分别为 p=0.735 和 0.816）。不同科室获得一个真阳性培养物所需的检测次数不同，范围为 7 至 45。
本研究表明血液培养在检测菌血症方面效率低下。入院后 24 小时内采集的培养物比后期采集的培养物产生更多的阳性结果。每个专业的血液培养流行病学和效率存在显著差异，表明应重新评估指南。未来的研究应旨在提高血液培养产量，实施减少污染和降低成本的现代分子诊断技术的教育计划。
