Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.
BMC Infect Dis. 2021 Feb 12;21(1):173. doi: 10.1186/s12879-021-05872-8.
Blood cultures are one of the most important tests performed by microbiology laboratories. Many hospitals, particularly in low and middle-income countries, lack either microbiology services or staff to provide 24 h services resulting in delays to blood culture incubation. There is insufficient guidance on how to transport/store blood cultures if delays before incubation are unavoidable, particularly if ambient temperatures are high. This study set out to address this knowledge gap.
In three South East Asian countries, four different blood culture systems (two manual and two automated) were used to test blood cultures spiked with five common bacterial pathogens. Prior to incubation the spiked blood culture bottles were stored at different temperatures (25 °C, in a cool-box at ambient temperature, or at 40 °C) for different lengths of time (0 h, 6 h, 12 h or 24 h). The impacts of these different storage conditions on positive blood culture yield and on time to positivity were examined.
There was no significant loss in yield when blood cultures were stored < 24 h at 25 °C, however, storage for 24 h at 40 °C decreased yields and longer storage times increased times to detection.
Blood cultures should be incubated with minimal delay to maximize pathogen recovery and timely result reporting, however, this study provides some reassurance that unavoidable delays can be managed to minimize negative impacts. If delays to incubation ≥ 12 h are unavoidable, transportation at a temperature not exceeding 25 °C, and blind sub-cultures prior to incubation should be considered.
血培养是微生物实验室进行的最重要的检测之一。许多医院，特别是在中低收入国家，缺乏微生物学服务或人员来提供 24 小时服务，导致血培养孵育延迟。如果在孵育前不可避免地出现延迟，特别是在环境温度较高的情况下，关于如何运输/储存血培养物的指导不足。本研究旨在解决这一知识空白。
在三个东南亚国家，使用四种不同的血培养系统（两种手动和两种自动）来测试五种常见细菌病原体污染的血培养物。在孵育之前，将污染的血培养瓶在不同温度（25°C，在环境温度下的冷藏箱中或 40°C）下储存不同的时间（0 h、6 h、12 h 或 24 h）。研究了这些不同储存条件对阳性血培养物产量和阳性时间的影响。
在 25°C 下储存<24 小时时，产量没有明显损失，然而，在 40°C 下储存 24 小时会降低产量，并且储存时间越长，检测时间就越长。
为了最大限度地提高病原体回收率和及时报告结果，应尽量减少血培养的孵育延迟，但本研究提供了一些保证，即在不可避免的延迟情况下，可以进行管理以尽量减少负面影响。如果孵育延迟≥12 小时不可避免，应考虑在不超过 25°C 的温度下运输，并在孵育前进行盲传代培养。
