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Reduction of turnaround time for non-tuberculous mycobacteria detection in heater-cooler units by propidium monoazide real-time PCR
Journal of Hospital Infection ( IF 3.9 ) Pub Date : 2019-10-16 , DOI: 10.1016/j.jhin.2019.10.010
S. Ditommaso , M. Giacomuzzi , G. Memoli , R. Cavallo , A. Curtoni , M. Avolio , C. Silvestre , C.M. Zotti

Background

Invasive non-tuberculous mycobacteria (NTM) infections are emerging worldwide in patients undergoing open-chest cardiac bypass surgery exposed to contaminated heater-cooler units (HCUs). Although this outbreak has been investigated by culturing bacteria isolated from HCU aerosol and water samples, these conventional methods have low-analytic sensitivity, high rates of sample contamination and long turnaround time (TAT).

Aim

To develop a simple and effective method to detect NTM in HCUs by real-time PCR, with a short laboratory TAT and reliable culture results.

Methods

A total of 281 water samples collected from various HCUs at 7 Italian hospitals were simultaneously screened for NTM by a propidium monoazide (PMA)-PCR assay and by conventional culture testing. The results were analyzed with culture testing being the reference method.

Findings

i) The agreement between culture testing and PMA-PCR was 85.0% with a Ct cut-off value of < 38 vs.80.0% with a Ct of < 43, with a moderate Cohen's kappa coefficient; ii) the Ct cut-off value of < 42 was deemed more suitable for predicting positive specimens; iii) given the low concentration of target DNA in water samples, the minimum volume to be tested was 1 lt.

Conclusion

We highly recommend the use of PMA-PCR for fast detection of NTM from environmental samples in order to ascertain whether HCUs may represent a potential source of human exposure to NTM. This reliable and simple method reduces laboratory TAT compared to conventional methods (1-2 days vs. 8 weeks, respectively), thereby improving control strategies and effective management of HCUs.



中文翻译:

通过单叠氮化丙锭实时定量PCR缩短加热器-冷却器单元中非结核分枝杆菌检测的周转时间

背景

在接受暴露于受污染的加热器冷却器(HCU)的开胸式心脏搭桥手术的患者中,世界范围内正在出现非侵入性非结核分枝杆菌(NTM)感染。尽管已经通过培养从HCU气溶胶和水样中分离出的细菌对这种暴发进行了调查,但这些常规方法的分析灵敏度低,样品污染率高且周转时间(TAT)长。

目的

开发一种简单有效的方法,通过实时PCR检测HCU中的NTM,具有较短的实验室TAT和可靠的培养结果。

方法

通过单叠氮化丙锭(PMA)-PCR分析和常规培养测试,同时对从7家意大利医院的各种HCU中收集的281个水样品进行了NTM筛查。以培养测试作为参考方法分析结果。

发现

i)培养测试和PMA-PCR之间的一致性为85.0%,Ct截止值<38,Ct截止值为80.0%,Ct <43,Cohen卡伯系数适中;ii)Ct截止值小于42被认为更适合预测阳性样本;iii)鉴于水样品中目标DNA的浓度低,要测试的最小体积为1升。

结论

我们强烈建议使用PMA-PCR快速检测环境样品中的NTM,以便确定HCU是否可能代表人类暴露于NTM的潜在来源。与常规方法相比(1-2天这可靠且简单的方法减少了实验室TAT分别为8周,),从而提高控制策略和HCUs的有效管理。

更新日期:2019-10-17
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