Two tests better than one to spot harmful mold infection

Aspergillus is among the world's most harmful molds. It infects the respiratory system and can lead to serious illness or death in patients with weakened immune systems. That makes early, effective diagnosis key to combating it, and a team of researchers from China and their colleagues believe they've found the ideal combination of tests to get the job done.

Scientists from the First Affiliated Hospital of Chongqing Medical University in China and others believe using both nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) can help detect the fungus in patients with total accuracy. The Journal of Molecular Diagnostics details their findings.

For their work, they tested three assays on blood samples from 80 patients at high risk of contracting invasive aspergillosis: NASBA, qPCR and an antigen-detection method known as GM-ELISA. According to the researchers, 42.5% of the patients either had invasive aspergillosis or likely had it.

They found that combining the tests helped boost the accuracy of any of them on their own. But NASBA and qPCR hit the jackpot when used together, identifying with 100% specificity and 100% probability that a subject had the infection. On its own, NASBA produced the highest sensitivity at 76.47%, and qPCR landed the highest specificity at 89.13%.

This finding, if it bears out in future testing, could help better manage the care of transplant patients, those with HIV, diabetes, lung disease and others with compromised immune systems. Using the NASBA and qPCR tests together, assuming they consistently produce a more accurate diagnosis, could help lead to better outcomes overall if patients stricken with invasive aspergillosis get quicker diagnosis and treatment, or the tests can also rule out when patents don't have the mold infection.

More testing of a wider patient pool will be necessary. The current standard of testing, which involves GM-ELISA testing, has a sensitivity of just under 53% and a specificity of just over 80%.

"The combination of NASBA and qPCR should be useful in excluding [invasive aspergillosis] in suspect cases, thus reducing both suffering and expense for immuno-compromised patients," lead researcher Yun Xia of Chongqing Medical University said in a statement.

A push for better diagnosis of invasive aspergillosis comes in tandem with drug company development of new treatments. Switzerland's Basilea ($BSLN), for example, said in June that it expected to file for regulatory approval in Europe this year to use its drug isavuconazole to treat invasive aspergillosis and mucormycosis. The company said its partner Astellas would pursue U.S. approval this year as well.

- read the release
- see the research abstract

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