Objectives: Invasive aspergilllosis (IA) continues to be a major complication of treatment for haematological malignancy (HM), and in haematopoietic stem cell transplant (SCT) recipients it is the most common cause of mortality due to infection. Earlier detection of Aspergillus infections would facilitate more effective management and prevent progression to invasive disease which typically has a poor response to antifungal drugs. We therefore evaluated two PCR assays for early detection of Aspergillus DNA in blood of patients being treated in two large haematology transplant centres. Methods: Between 2007-2008 consecutive HM patients who were undergoing chemotherapy, autologous (only one centre), allogeneic sibling or unrelated donor SCT were eligible for inclusion into the study. Three EDTA whole blood samples were collected twice weekly from all study patients who were monitored for IA and other invasive fungal diseases (IFD) throughout their inpatient treatment using the European Organization for Research and Treatment of Cancer/Infectious Diseases Mycoses Study Group consensus criteria for defi ning IFD. Sera were routinely processed for circulating galactomannan (GM, Biorad) and reported to the clinical team. Samples were processed in batches for PCR. Staff performing the assays were blind to clinical details. Assay 1 (PCR1) was a nested PCR as published by White et al (Clinical Infectious Diseases 2006, 42;479) targeting the 28S Aspergillus ribosomal gene region, while assay 2 (PCR2) was a real-time PCR developed in-house targeting the ITS ribosomal region. Results: 300 patients in total were included, equal numbers coming from each centre over the two-year study period. There was only 1 case of proven IA and 23 probable IA cases. Overall, there were approximately 4,000 blood samples processed by each PCR assay. The frequency of positive test results were for centre 1: GM, 7.6%, PCR1, 8.1%, and PCR2, 2.2%, and for Centre 2: GM, 7.5%, PCR1, 5.5%, PCR2, 8.3%. This suggested there was a centre-specifi c effect particularly with regard to PCR2. In cases of probable/proven IA all 3 assays gave positive results but there were more positive samples with GM compared to either PCR assay. Conclusion: When PCR is used in a complementary way to GM assay it is a useful tool for detection of Aspergillus infection. Further standardisation of PCR is necessary before its more universal application for diagnosis of IA.
Full conference title:
Annual Meeting of the EBMT, 37th
- EBMT 37th (2011)