Comparison of real-time Aspergillus polymerase chain reaction (PCR) with Plateliaâ„¢Aspergillus enzyme immunoassay (EIA) in broncho-alveolar lavage fluids for the diagnosis of invasive aspergillosis in neutropenic and non-neutropenic patients

Ref ID: 19196

Author:

N. Ruzicka, R. Boreux, L. Levaux, C. Meex, P. Huynen, J. Descy, M. Dodemont, P. Melin, M.-P. Hayette

Author address:

Liège, BE

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objectives: Because of low sensitivity of fungal cultures and lack of standardization of Aspergillus PCR, laboratory diagnosis of invasive aspergillosis still relies on galactomannan (GM) detection in broncho-alveolar lavage (BAL) fluids and serum. The aim of this study was double: first, to assess the place of a 18S rRNA Aspergillus real-time PCR test performed in BAL fluid for the diagnosis of invasive aspergillosis (IA) in neutro- and non-neutropenic patients in comparison with GM detection; secondly, to evaluate the use of three different GM cut-off values.
Materials and methods: A total of 111 neutropenic and non-neutropenic patients hospitalized at the University Hospital of Liège from March to October 2012 with suspicion of IA were included in the study. A total of 138 broncho-alveolar lavage fluids were evaluated by three laboratory diagnostic methods: 1/ culture on Sabouraud agar slants with antibiotics (bioMí©rieux) incubated at 28°C for 28 days; 2/ GM detection (Platelia â„¢Aspergillus EIA, Biorad) using GM index cut-off values at 0.5, 0.8 and 1, performed three times a week; 3/ a real-time Aspergillus PCR assay performed daily and targeting 18S rRNA genes using an in-house method. Clinical, radiological and microbiological data were reviewed for classification of patients.
Results: Nine patients developed probable or possible IA. The sensitivity/specificity/positive (VPP) and negative (NPV) predictive values (%) for culture, PCR, and GM using 0,5 as cut-off value were respectively 41/100/100/94, 58/97/70/96, and 91/83/34/99. The use of 0,8 and 1 as GM index cut-off values increased the specificity to 89 and 92% respectively, and the VPP to 44 and 54%. PCR had a better turn-around time and allowed the detection of Aspergillus colonisation in two patients.
Conclusion: GM detection in BAL fluids using a cut-off value of 1 was the most efficient laboratory test for the diagnosis of IA in neutropenic and non-neutropenic patients. Despite a lower sensitivity, PCR had a better VPP, and allowed the detection of culture-negative Aspergillus colonisations. A shorter turnaround time (TAT) due to daily practice of PCR tests may reduce the time-to-treatment up to 24 hours.

Abstract Number: P1072

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=166405&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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