We aimed to assess the clinical relevance of the marketed pan-mucorales real-time PCR assay MucorGenius® (Pathonostics) on pulmonary specimens relative to that of in-house PCR assays and conventional mycology for the diagnosis of mucormycosis.

In total, 319 pulmonary samples from severely immunosuppressed patients at risk for invasive mold disease (IMD) were retrospectively included. Direct examination, mycological culture, and PCR testing were performed using three genus-specific in-house mucorales real-time PCR assays and MucorGenius®PCR. Results from Aspergillus testing, including galactomannan and PCR, were also collected.

The 319 patients were graded according to modified EORTC-MSG criteria as proven/probable mucormycosis (n=6), proven/probable invasive aspergillosis (IA) (n=63), Aspergillus–mucorales co-infections (n=4), possible IMD (n=152), and excluded IMD (n=94). The in-house and MucorGenius®PCR assays were positive for 33 (10.3%) and 27 (8.5%) samples, respectively, whereas culture was positive for only 10 (3.1%). The in-house and MucorGenius®PCR assays showed a sensitivity of 100% (10/10) and 90% (9/10) and a specificity of 95.7% and 97.9%, respectively. Both PCR assays allowed the detection of mucorales DNA in samples from 10 possible cases and six IA, all missed by culture.

MucorGenius® showed good performance, despite missing some low fungal burden. Combining mucorales PCR with EORTC-MSG criteria greatly improved the diagnosis of mucormycosis.