Comparative Performances Of 2 Pcr Assays For The Detection Of aspergillus In Bronchoalveolar Lavage Fluid During The Diagnosis Of Invasive Aspergillosis

P. COMACLE, S. BELAZ, F. ROBERT-GANGNEUX, S. CHEVRIER, J-P. GANGNEUX

Author address: 

CHU Pontchaillou, Rennes, France

Abstract: 

Background: Aspergillus detection in the BAL fluid is one of the criteria for the diagnosis of proven and probable invasive aspergillosis (IA). Beside mycology (direct examination and/or culture) and galactomannan (GM) detection that are identified as EORTC/MSG criteria for probable IA (de Pauw 2008), PCR on pulmonary samples has become an essential argument for the laboratory diagnosis. Various amplification methods have been published but without consensus.Methods: The aim of this work was to compare the performance of two amplification targets: A. fumigatus mitochondrial gene (AFmito) and 28S rRNA. From 01/2012 to 10/2015, 324 BALF were prospectively collected and tested for mycology examination, GM detection (EIA Platelia assay Biorad, cutoff 1.0 if isolated, and 0.8 if associated to serum GM > 0.5) and AFmito PCR assay. Beside, 28S PCR assay was retrospectively performed on the same DNA extracts (312/324 available DNA). Results: According to the 2008 modified criteria of EORTC/MSG for classification of IA, patients were classified as: 1 proven, 47 probable and 11 possible IA. Other patients were classified as 11 with colonization and 256 non-infected. Sensitivity of BALF GM detection, 28S PCR assay and AFmito PCR assay was 58%, 61% and 50%, respectively. Mycology testing (ED +/- culture) had a sensitivity of 33%. Specificity of BALF GM detection, 28S PCR assay, AFmito PCR assay and culture was 94%, 97%, 97% and 98%, respectively. Negative predictive value was 93%, 95%, 92% and 89%, respectively. Concordance between the 2 PCR assays was 97% (kappa coefficient 0.84), whereas it was 88% (kappa 0.40) between 28S PCR and BALF GM and 88% (kappa 0.43) between Afmito PCR and BALF GM. Conclusions: 28S PCR assay had the highest performance for the molecular detection of Aspergillus in BALF compared to AFmito. The combination of 28S PCR assay and GM detection in BALF allowed to reach a sensitivity of 80% with a conserved high specificity (91%).
2016

abstract No: 

MONDAY-241

Full conference title: 

ASM Microbe 2016
    • ASM microbe 1st (2016)