Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
J Clin Microbiol. 2021 Jun 18;59(7):e0042921. doi: 10.1128/JCM.00429-21.
New blood culture instrumentation and medium formulations have led to improved time to positivity (TTP) for positive blood cultures. Data regarding the necessity of pediatric blood culture bottles with contemporary blood culture systems are sparse. We compared performance of three commercial blood culture systems, evaluating impact of blood volumes in standard and pediatric blood culture media across systems. Simulated blood cultures with packed red blood cells (PRBCs) and three Gram-positive, four Gram-negative, and one anaerobic organism (final concentrations ranging from 0.5 to 19 CFU/ml blood) on the Virtuo, VersaTrek, and Bactec FX instruments were evaluated with FAN Plus, Redox, and Bactec Plus media, respectively. For each medium/instrument/organism combination, 1-, 3-, 5-, and 10-ml blood volumes were evaluated in triplicate. Detection rate was not affected by blood volume. Aerobic organisms that demonstrated variable rates of detection were Kingella kingae, Haemophilus influenzae, and Neisseria meningitidis. Bacteroides fragilis was detected in 83%, 100%, and 100% of Virtuo, VersaTrek, and Bactec anaerobic bottles, respectively. The average TTP of standard medium for aerobic organisms detected on Virtuo was decreased compared to those for VersaTrek (-2.3 h) and Bactec (-4.9 h). Compared to standard medium, detection rate and TTP were unchanged on Virtuo, while TTP was reduced with pediatric medium for 2/8 organisms tested on Bactec and 7/8 organisms on VersaTrek, illustrating the potential benefit of pediatric medium on VersaTrek or Bactec when low blood volumes (<5 ml) are collected. These results demonstrate that TTP is decreased on the Virtuo compared to VersaTrek and Bactec for many microorganisms associated with bloodstream infection (BSI) but may have species-specific limitations.
新的血培养仪器和培养基配方提高了血培养阳性的阳性时间 (TTP)。关于当代血培养系统中儿科血培养瓶的必要性的数据很少。我们比较了三种商业血培养系统的性能，评估了系统间标准和儿科血培养培养基中血量对系统的影响。使用 FAN Plus、Redox 和 Bactec Plus 培养基分别评估了 Virtuo、VersaTrek 和 Bactec FX 仪器上用浓缩红细胞 (PRBC) 和三种革兰氏阳性菌、四种革兰氏阴性菌和一种厌氧菌（终浓度范围为 0.5 至 19 CFU/ml 血液）模拟的血培养。对于每种培养基/仪器/生物体组合，在三重复条件下评估了 1、3、5 和 10ml 血量。检测率不受血量影响。检测率不同的需氧生物体为金氏金菌、流感嗜血杆菌和脑膜炎奈瑟菌。脆弱拟杆菌分别在 Virtuo、VersaTrek 和 Bactec 厌氧瓶中检测到 83%、100%和 100%。与 VersaTrek（-2.3 小时）和 Bactec（-4.9 小时）相比，Virtuo 上检测到的需氧生物体的标准培养基的平均 TTP 降低。与标准培养基相比，Virtuo 的检测率和 TTP 保持不变，而儿科培养基的 TTP 降低了，在 Bactec 上测试的 8 种生物体中的 2 种和在 VersaTrek 上测试的 8 种生物体中的 7 种，这表明在采集低血量（<5ml）时，儿科培养基对 VersaTrek 或 Bactec 可能具有潜在的益处。这些结果表明，与 VersaTrek 和 Bactec 相比，许多与血流感染（BSI）相关的微生物在 Virtuo 上的 TTP 降低，但可能存在物种特异性限制。
