Aspergillus spp. / Mucorales duplex PCR assay inputs for the diagnosis of Aspergillus/ Mucorales coinfections

Author:

Sebastien Imbert (FR)

Abstract:

Background: Invasive mould infections (IMI), including invasive aspergillosis (IA) and mucormycosis (MM) are life-threatening diseases occurring mainly in critically ill patients. As risk factors and contamination routes are similar in IA and MM, Aspergillus/Mucorales coinfections can occur and even reach 40% in high risk patients. Although an early targeted antifungal therapy is essential for IMI management and therapeutic success, coinfections diagnosis is still challenging. Indeed, clinical and radiological features are not specific and conventional mycological methods may lack sensitivity (especially in mucormycosis). In last years, molecular tools such as real-time PCR, have greatly improved the diagnosis of IA and MM separately. However, the use of overly specific PCR assays can lead to under-diagnosis of coinfections. In our center we have been using since September tember 2020, a duplex PCR assay targeting the Aspergillus genus and the Mucorales order simultaneously (MycoGenie, Ademtech). This PCR assay is used routinely in serum, respiratory samples or others deep-seated samples, for screening in high risk patients and/or for targeted diagnosis in suspected IMI patients. Here, we aimed to study this duplex PCR assay inputs for the diagnosis of Aspergillus/Mucorales coinfections.
Methods: We analyzed retrospectively our PCR assay results obtained between March 2020 and July 2023. In a second part, we assessed specifically its clinical performances on serum between September 2020 and August 2021, and on broncho-alveolar lavage (BAL) between January 2021 and May 2022.
Results: Over the global study period, 4436 patients underwent an Aspergillus/Mucorales PCR assay on diverse sample types. Among them, 441 (9.9%) and 173 (3.9%) were positive for the Aspergillus and the Mucorales targets respectively. Interestingly, 50 (1.1%) patients were positive for both targets, including 32 both positive on the same sample, and 18 on successive samples. Regardless of the final diagnosis, 11.3% of patients were positive for the Mucorales target when the Aspergillus target was positive, and 28.9% conversely. Regarding clinical performances on serum, 55 IMI were identified among 744 high risk patients, including 39 IA and 20 MM. Among them, 4 Aspergillus/Mucorales coinfections were detected, corresponding to a 10.2% and 20% coinfection rate in IA and MM respectively. Interestingly, only 7 (35%) MM were detected by fungal culture, whereas no coinfection was detected by conventional methods. Regarding clinical performances on BAL, 75 and 21 patients were positive for the Aspergillus and the Mucorales targets respectively, among 938 at risk patients. Only 11 of the 21 Mucorales-PCR positive patients had a MM, including 4 with an Aspergillus/Mucorales coinfection. This corresponded to a 36% coinfection rate in MM. Only 3 (27%) MM were detected by fungal culture whereas no coinfection was detected by conventional methods.
Conclusions: The use of the Aspergillus spp. / Mucorales duplex PCR assay improved greatly the MM diagnosis, in comparison to conventional methods, especially in case of Aspergillus coinfection. Moreover, the high coinfection rate detected on BAL and serum highlights the importance to screen systematically high-risk patients for coinfection in case of IA or MM, by molecular assays, to improve IMI management.

Abstract Number: 32

Conference Year: 2024

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