Evaluation of a PCR and Culture Assays To Detect aspergillus DNA in a Murine Model of Invasive aspergil*osis.

Hermann Einsele, Juergen Loeffler, Kerstin Kloepfer, Laura Najvar, John R. Graybill, Holger Hebart.

Author address: 

Department of Hematology and Oncology, Eberhard Karls University, Tuebingen, Germany; Department of Medicine, University of Texas Health Science Ctr., San Antonio, TX, USA

Abstract: 

Invasive aspergillosis (IA) is one of the most common and life-threatening infections in patients receiving antileukemic therapy. Culture assays from blood samples are hardly ever positive even in pts. with IA. Preliminary results of PCR testing of blood samples in patients following intensive chemotherapy are rather promising To compare PCR and culture assays in detecting aspergillosis spp. not only in blood specimens, but also in the target organ of invasive aspergil*osis, the lung, PCR and culture assay were evaluated in a murine model of invasive aspergil*osis. Quantification of fungal load in blood and tissue was performed by quantitative culture assay and a quantitative Real-Time PCR assay established on the LightCycler. 82 mice were infected intranasally with aspergillus conidia. Animals were sacrificed and defined sizes of lung tissue were homogenized and divided into 2 identical aliquots. 297/397 lung biopsy specimens (78%) showed a positive PCR result, whereas only 235/379 (62%) were positive by culture assay. Fungal load, as determined in 30 lung biopsy specimens by quantitative PCR assay, was 103-105 CFU/g. Sixty-four culture-negative lung biopsy specimens were positive by PCR, but only 2 PCR-negative samples were tested positive by culture assay. In order to compare the results of both assays, a statistical model was fitted in which the probability of a positive PCR result was calculated as a function of the amount of A. fumigatus-CFU. These results revealed the PCR assay to be 3.87 times more sensitive than the detection of fungi by culture for demonstrating fungal presence in lung biopsies (95%-CI: 2.96 - 5.01, p
2001

abstract No: 

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Full conference title: 

43rd American Society of Hematology (ASH) Annual Meeting
    • ASH 43rd (2001)