Development and Validation of Fungal Extraction and Real -Time PCR Assay for the Diagnosis of Medically Important Fungal Infections in Blood Samples.
Invasive fungal infections are a major cause of morbidity and mortality in immunocompromised
patients. Among them, patients with hematological malignancies, neutropenic patients, human
immunodeficiency virus infected patients, diabetics, solid organ transplanted patients and
patients admitted in an intensive care unit are particularly at high risk.
The survival of these patients depends on early diagnosis and prompt appropriate antifungal
treatment. The early diagnosis of these infections is difficult because of the lack of
sensitive test methods, notably blood cultures. Its sensitivity is poor or close-zero for
aspergillosis. In addition, the response time is several days. For these reasons, we decided
to develop a real-time PCR (Polymerase Chain Reaction) assay on blood samples. It should
allow rapid response to establish a positive or negative diagnosis of invasive fungal
infection, it could contribute strongly to the decision of treating using antifungals, and
it should monitor the effectiveness and the optimization of antifungal prescriptions.
Our project is a multicentre prospective inter-regional collaborative work between Nice,
Rennes and Toulouse Mycological and parasitological laboratories. Our objectives are: First,
to validate an extraction method from blood infected by fungi species. The three
laboratories will work together to determine the best extraction method, since there is no
consensus method for the extraction of nucleic acids of fungal origin in the context of
human infections. The numerous extraction techniques already used lead to differences in the
PCR results. As a consequence, inter-laboratory comparisons are not easy. Secondly, we aim
to develop three real-time PCR assays: A panfungal real-time PCR assay able to detect most
fungal species responsible for human diseases; a real-time PCR assay targetting Candida
albicans and one targeting Aspergillus fumigatus which are two clinically important
pathogens. Then patient blood samples (classified according to EORTC consensus) will be
collected during the study in order to evaluate and validate our method on clinical samples.
Results will allow us to determine the sensitivity, specificity and reproducibility,
negative and predictive values.
Objectives Overall, our work aims to evaluate the clinical impact of real-time PCR in the
early diagnosis of invasive fungal infections and on the initiation or stopping of
antifungal therapy. The economic impact resulting from the use of this method will be
evaluated. Indeed, an excellent predictive negative value of a panfungal real-time PCR assay
could warrant a decrease in the use of empirical antifungal therapy
Endpoint Classification: Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Diagnostic
The evaluation will be conducted on blood samples inoculated with known concentrations of numerous fungal species (various Candida sp, various Aspergillus sp., Cryptococcus sp. etc…). Extraction method and PCR techniques
MARTY Pierre, PhD
CHU de Nice - laboratoire de parasitologie- Hôpital de l'Archet - 151 Route de saint-antoine de ginestière 06200 Nice
France: Direction Générale de la Santé