Molecular diagnostic platforms for detecting Aspergillus

Invasive aspergillosis remains difficult to diagnose despite advances in imaging and antigen-based serological testing. To overcome this problem, nucleic acid (NA)-based amplification assays were introduced to identify infecting pathogens. Unfortunately, the reliability of such assays to detect Aspergillus spp. has met with mixed success. A new generation of NA platforms are emerging, which greatly improve our ability to detect Aspergillus-specific DNA and RNA from respiratory and blood samples. These platforms can accurately detect a single genome, and the emergence of pan-fungal and pan-Aspergillus probes offer promise for broader detection. PCR remains the most important platform, especially when coupled with real-time probes. It is multiplex friendly and can distinguish between closely related target sequences. Nucleic acid sequence-based amplification (NASBA) is an RNA-directed isothermal transcription-based amplification platform, which is more robust than PCR resulting in a 1014-fold amplification. RNA-based detection facilitates more target options and can be used to assess cell viability. Both DNA and RNA amplification platforms take advantage of allele-specific properties of probes, which are valuable for assessing drug resistance markers. Finally, as new molecular diagnostic platforms mature, their role may expand to include early monitoring of therapy.