Comparison of real-time PCR, nested PCR, and galactomannan antigen detection by enzyme-linked immunosorbent assay in sera for diagnosis of invasive aspergillosis

Abstract

Conventional methods for diagnosis of invasive aspergillosis (IA) lack sensitivity and specificity. Serological methods still have many cases of cross-reactivity. However, molecular techniques seem to arise as a rapid approach, specific and direct that could be used in the diagnosis of IA. In this study, we analyzed 88serum samples from patients of having IA using GM-ELISA test, nested PCR with primers for the rRNA 18S of Aspergillus genus and real time PCR specific for A.fumigatus. Among the 88samples, 64of them had positive GM titers and 23had positive nested PCRs; 18of the 23PCR-positive samples were also GM-positive. On the other hand, 18samples were detected positive by reel time PCR; 13positive samples were also detecting positive by nested PCR. QPCR revealed 26% of the patients with IA, while nested PCR and galactomannan ELISA revealed respectively 34% and 94% of the patients with IA. Probable IA was diagnosed in 18and possible IA was diagnosed in 6episodes. Forty-four episodes were defined as not having IA. The positive and negative predictive values were respectively 100%, and 88% for QPCR, 100% and 97% for nested PCR, and 28% and 60% for GM test. These results suggesting that combined use of methods might improve the diagnosis of IA.