Bisognin Francesco, Borghi Michele, Faccio Matteo, Ferraro Vincenzo, Sorella Federica, Crovara Pesce Cristina Maria, Primavera Alessandra, Dal Monte Paola
Microbiology Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, Bologna, Italy.
Department of Medical and Surgical Sciences, Alma Mater Studiorum - University of Bologna, Bologna, Italy.
Sci Rep. 2024 Dec 28;14(1):31173. doi: 10.1038/s41598-024-82440-5.
Mycobacterium chimaera, belonging to the Mycobacterium avium complex, is an opportunistic environmental mycobacterium which has been isolated from medical device water samples such as Heater Cooler Units (HCU). Laboratories currently use culture-based diagnostic methods to detect M. chimaera, but these take a long time to obtain results. The aim of this study is to test and define the Limit of Detection (LoD) of a Real-Time Polymerase Chain Reaction test (RT-PCR) specific for M. chimaera, using a sample-to-result InGenius platform, performed on medical device water samples collected at the referral centre for the detection of mycobacteria from environmental specimens of Bologna, Italy. A total of 285 water samples were included in this study. The sensitivity and specificity of RT-PCR compared to culture were 60.5% and 98.8% respectively, with an overall agreement of 82.1% and a positive predictive value of 97.4%. The LoD calculated was approximately 2900 CFU/ml. In conclusion, this study confirmed that detection of M. chimaera with RT-PCR could support culture-based methods in reducing the time necessary to identify highly colonised HCUs, with high positive predictive values. Therefore, we suggest performing this customised RT-PCR on concentrated decontaminated water samples, shutting down and thoroughly disinfecting positive HCUs, to reduce the risk of patient infection.
嵌合体分枝杆菌属于鸟分枝杆菌复合群，是一种机会性环境分枝杆菌，已从诸如热交换器（HCU）等医疗设备水样中分离出来。目前实验室使用基于培养的诊断方法来检测嵌合体分枝杆菌，但这些方法获得结果所需时间较长。本研究的目的是使用样本到结果的InGenius平台，对在意大利博洛尼亚环境标本分枝杆菌检测转诊中心收集的医疗设备水样进行检测，并确定一种针对嵌合体分枝杆菌的实时聚合酶链反应试验（RT-PCR）的检测限（LoD）。本研究共纳入285份水样。与培养法相比，RT-PCR的灵敏度和特异性分别为60.5%和98.8%，总体一致性为82.1%，阳性预测值为97.4%。计算得出的检测限约为2900 CFU/ml。总之，本研究证实，用RT-PCR检测嵌合体分枝杆菌可以辅助基于培养的方法，减少识别高度定植的热交换器所需的时间，阳性预测值较高。因此，我们建议对浓缩的净化水样进行这种定制的RT-PCR检测，关闭并彻底消毒呈阳性的热交换器，以降低患者感染风险。
