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Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).
The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.
So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.
The team reported this discovery in The Journal of Molecular Diagnostics.
IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.
“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.
With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.
The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.
Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.
NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.
NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.
And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.
Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.
Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR. 
Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).
The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.
So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.
The team reported this discovery in The Journal of Molecular Diagnostics.
IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.
“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.
With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.
The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.
Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.
NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.
NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.
And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.
Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.
Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR.
Results of a retrospective study may have revealed the most accurate way to diagnose invasive aspergillosis (IA).
The fungal infection can be life-threatening, particularly for immunosuppressed patients, but it remains difficult to diagnose.
So researchers compared 3 tests used to diagnose IA and found the combination of nucleic acid sequence-based amplification (NASBA) and real-time quantitative PCR (qPCR) had a 100% positive predictive value.
The team reported this discovery in The Journal of Molecular Diagnostics.
IA is caused by the fungus Aspergillus fumigatus, which is considered by many pathologists to be the world’s most harmful mold.
“Traditional diagnostic methods, such as culture and histopathology of infected tissues, often fail to detect Aspergillus,” said study investigator Yun Xia, PhD, of the First Affiliated Hospital of Chongqing Medical University in China.
With this in mind, he and his colleagues evaluated the diagnostic performance of 2 nucleic acid amplification assays—qPCR and NASBA—and 1 antigen-detection method—galactomannan enzyme-linked immunosorbent assay (GM-ELISA)—using blood samples from 80 patients at high risk of IA.
The researchers evaluated the tests alone and in combination. Of the 80 patients, 42.5% had proven or probable IA.
Tests showed that NASBA predicted IA with the highest sensitivity—76.47%, compared to 67.65% for qPCR and 52.94% for GM-ELISA. But qPCR offered the highest specificity—89.13%, compared to 80.43% for both NASBA and GM-ELISA.
NASBA had the highest negative predictive value—82.22%, compared to 78.85% for qPCR and 69.81% for GM-ELISA. And qPCR had the highest positive predictive value—82.14%, compared to 74.29% for NASBA and 66.67% for GM-ELISA.
NASBA and qPCR each had a high Youden index as well—0.5690 and 0.5678, respectively—compared to GM-ELISA—0.3337.
And combining the tests improved their accuracy. The combination of NASBA and qPCR led to 100% specificity and a 100% positive predictive value.
Dr Xia and his colleagues also noted that NASBA offers the advantages of rapid amplification (90 minutes) and simple operation with low instrument cost, compared with qPCR and GM-ELISA.
Finally, the team stressed that although GM-ELISA is widely and routinely used for aspergillosis diagnosis, this study indicates that it is inferior to both NASBA and qPCR.