Department of Medicine, University of California, San Diego, CA, USA.
Singapore General Hospital, Singhealth, Singapore.
J Hosp Infect. 2020 Jun;105(2):252-257. doi: 10.1016/j.jhin.2020.02.015. Epub 2020 Feb 26.
Heater-cooler units (HCUs) have been implicated in the recent global outbreak of invasive Mycobacterium chimaera infection among patients following cardiothoracic surgery. Because infected patients tend to remain asymptomatic for extended periods, detection of M. chimaera from HCUs in real time is essential to halting the ongoing M. chimaera HCU-associated outbreak. Sample collection protocols to evaluate the presence of M. chimaera offer conflicting recommendations regarding the addition of sodium thiosulfate (NaT) during the collection process.
To study the effect of NaT on M. chimaera recovery and culture contamination.
Seventy-six paired HCU water samples (with and without NaT) were collected, processed and cultured simultaneously into Lowenstein-Jensen slants, Middlebrook 7H10 agar plates, and mycobacterial growth indicator tubes (MGITs), and incubated at 37°C. A subset of 31 paired samples was additionally cultured on MGITs and incubated at 30°C.
Of 76 samples incubated at 37°C in each of the three media, with and without NaT, M. chimaera was identified in at least one aliquot of 21 samples.
The presence of NaT did not significantly increase the probability of recovering M. chimaera in a multi-variable conditional logistic model and culture contamination rates were similar between aliquots with and without NaT. In the subset of samples cultured on MGITs at both 30°C and 37°C, the presence of NaT again was not associated with M. chimaera recovery, but was significantly associated with reduced culture contamination.
热交换器（HCU）已被怀疑与近期全球范围内心胸手术后侵袭性丘氏分枝杆菌感染有关。由于受感染的患者可能会持续无症状延长时间，因此实时从 HCU 检测分枝杆菌对于阻止正在进行的分枝杆菌 HCU 相关爆发至关重要。评估是否存在分枝杆菌的样本采集方案在采集过程中添加硫代硫酸钠（NaT）方面提供了相互矛盾的建议。
研究 NaT 对丘氏分枝杆菌回收和培养污染的影响。
同时收集 76 对 HCU 水样（加和不加 NaT），并进行处理和培养，同时将其接种到 Lowenstein-Jensen 斜面、Middlebrook 7H10 琼脂平板和分枝杆菌生长指示剂管（MGIT）中，并在 37°C 下孵育。一小部分 31 对配对样本在 MGIT 上额外培养，并在 30°C 下孵育。
在每个三个培养基中 37°C 孵育的 76 个样本中，加和不加 NaT ，至少有 21 个样本的一个等分试样中鉴定出了丘氏分枝杆菌。
多变量条件逻辑回归模型显示，NaT 的存在并未显著增加回收丘氏分枝杆菌的可能性，且有无 NaT 的等分试样的培养污染率相似。在分别在 30°C 和 37°C 下在 MGIT 上培养的样本子集中，NaT 的存在再次与分枝杆菌的回收无关，但与培养污染的减少显著相关。
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