P44

Background Mycobacterium chimaera is an opportunistic environmental mycobacterium commonly associated with pulmonary disease, which has recently been associated with invasive infections following cardiac surgery. Laboratories currently use culture-based diagnostic methods to detect M. chimaera in water samples from Heater Cooler Units (HCU) used during surgery, but these take a long time to report the results. The goal of this study is to develop a rapid and accurate Real-Time Polymerase Chain Reaction test (RT-PCR) specific for M. chimaera, using a sample-to-result InGenius platform (ELITechGroup, Italy), including Mycobacterial DNA extraction.

Methods Water samples (1 liter) were concentrated 100 times by filtration and decontaminated with NALC-NaOH Solution (BD BBL MycoPrep™ System, USA). The RT-PCR reagents (Thermo Fisher Scientific, USA) have been previously described by Zozaya-Valdés et al. on Journal of Clinical Microbiology in 2017. Extraction and RT-PCR were performed on InGenius platform.

Results 40 water samples from HCU devices were selected for this study: 20 water samples were M. chimaera culture-positive and 20 were culture-negative. 18 out of 20 culture-positive water samples resulted RT-PCR positive for M. chimaera, while 2 were negative. All culture-negative samples were RT-PCR negative. The sensitivity and specificity were 90% (CI95: 0.699 - 97.21) and 100% (CI95: 0.839 –1) respectively.

Conclusions In conclusion, this small pilot study showed that detection of M. chimaera with RT-PCR could support culture-based methods reducing the time taken to shut down HCUs in the event of positivity. However, culture should still be performed, as molecular methods could detect genome fragments of non-viable bacilli.