Boch T, Spiess B, Heinz W, et al. - Researchers conducted this retrospective multicenter analysis to systematically evaluate the diagnostic performance of an Aspergillus-specific nested polymerase chain reaction (PCR) by examining specimens from the site of infection and comparing it with concurrent blood samples in individual patients with invasive aspergillosis (IA), a severe complication in immunocompromised patients. They performed PCR on clinical specimens (n = 138) of immunocompromised high-risk patients (n = 133) from the site of infection together with concurrent blood samples. During antifungal prophylaxis/antifungal therapy, a significantly higher performance of PCR from the infection site was noted. In addition to 85% specificity, sensitivity differed significantly in bronchoalveolar fluid (64%), cerebrospinal fluid (100%), tissue samples (67%) compared with concurrent blood specimens (8%). The findings highlight how clinical samples from the infection site are needed to determine or rule out the diagnosis in case of suspected IA.