Early diagnosis and treatment of Invasive aspergillosis (IA) remains challenging. Despite advances in molecular tools, gold standard for diagnosis still relays on direct microscopy and culture. Although culture based methods are very useful for species determination and antifungal resistance detection, the sensitivity and the turnaround time are poor. Non-cultural methods such as galactomannan (GM) beta glucan test and PCR have been widely tested in the last decades. GM remains a keystone in the diagnosis of IA with very good performance in haematological and solid organ transplant patients although false positive results are still an issue. Several efforts have been conducted in the last years to evaluate the performance of PCRs for diagnosis of IA. The low amount of circulating DNA in clinical samples is the main challenge of this technique. The variety of test available and the lack of conclusive and robust results are the main pitfalls for their inclusion in the diagnostic pipeline that is still under debate. A Lateral-flow device have been developed giving promising results when used in BAL samples although it is not commercially available. The emergence of antifungal resistance is another challenge in IA. Azole resistance in A. fumigatus have been described worldwide reaching high rates in some European countries. On the other hand, between 10 to 15% of mould infections can be due to intrinsically resistant species. These strains have been related with poorer outcomes and therefore their detection is essential to guide treatment. Resistance detection has mainly relay in antifungal susceptibility testing, however other tools have been developed in the last years, although their usefulness in clinical practice has to be validated. This resistance is expected to increase because of the extensive use of azoles both in agriculture and as prophylaxis. Therefore, the detection of antifungal resistance in IA is becoming one of the main roles of clinical laboratories in order to guide antifungal treatment and improve patient outcomes.
Full conference title:
- TIMM 8th (2017)