Culture of blood is the most frequent means of diagnosing bacteremia. However, conventional blood culturing methods are slow in isolating bacteria. We developed a method for isolation of bacteria by centrifugation and filtration. Fresh human whole blood was inoculated with facultatively anaerobic and aerobic microorganisms (3 to 172 microorganisms per 5 ml). Seeded blood was then mixed with Ficoll-Hypaque (density, 1.149 +/- 0.002 g/ml) and centrifuged (386 x g) for 30 min at ambient temperature. The entire gradient (plasma, leukocytes, and Ficoll-Hypaque) was removed and filtered through a 0.22-micron membrane filter (Millipore). The filters were then placed on chocolate agar plates and incubated at 35 degrees C in a humidified atmosphere containing 5% CO2. For each bacterium tested, approximately 35 to 100% of the viable microorganisms were recovered when compared with control cultures (pour plates of seeded blood). All bacteria produced isolated colonies on filters after overnight incubation (18 h). This procedure may prove to be a more rapid method for isolating bacteria from clinical blood samples than the blood culture bottle technique.
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机译：血液培养是诊断菌血症的最常见手段。然而，常规的血液培养方法在分离细菌方面很慢。我们开发了一种通过离心和过滤分离细菌的方法。新鲜的人全血接种兼性厌氧和好氧微生物（每5 ml中3至172个微生物）。然后将接种的血液与Ficoll-Hypaque（密度为1.149 +/- 0.002 g / ml）混合，并在环境温度下离心（386 x g）30分钟。除去整个梯度（血浆，白细胞和Ficoll-Hypaque），并通过0.22微米的膜滤器（Millipore）过滤。然后将滤器放置在巧克力琼脂板上，并在35℃下在含有5％CO 2的潮湿气氛中温育。与对照培养物（倒入接种血的平板）相比，对于每种测试细菌，大约可回收35-100％的活微生物。过夜孵育（18小时）后，所有细菌均在过滤器上产生分离的菌落。与血液培养瓶技术相比，该方法可能被证明是从临床血液样本中分离细菌的更快方法。
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