Detection of Aspergillus Species in Blood of Malignant Hemotopoietic Tumor Patients by Two-Step PCR.

Objective To investigate the sensitivity and specificity of two-step PCR in detection of aspergillus species in blood from malignant hemotopoietic tumor patients. Methods Forty-one blood samples from patients at high-risk for invasive fungal disease were detected by two-step PCR. The clinic applicability of two-step PCR for systemic aspergillosis diagnosis was assessed by analyzing computed tomography, aspergillus culture, neutropenia and outcome after anti-fungal therapy. Results Specific band of PCR was obtained from aspergillus strains and the products of PCR had a high homogeneous in sequence with aspergillus species. Sixteen of 41 patients were PCR positive, aspergillosis was proven in 4 of these patients by the results of culture. The controls (12 healthy) were all PCR negative. The eight patients (of the 16 PCR positive patients) had characteristic high-resolution computed tomography findings that suggested invasive aspergillosis. The minimum value of white blood cell (WBC) was 0.3×10⁹/L±0.14×10⁹/L in PCR positive patients, whereas, was 0.5×10⁹/L ±0.26×10⁹/L in PCR negative patients (p=0.0326). The duration with WBC count less than 1.0×10⁹/L was 19±8.313 days and 12.69±6.945 days respectively between two groups (p=0.0472). After antifungal therapy, one of the patients with PCR positive died of chemotherapy-related early death. Conclusions The two-step PCR assays allows for the highly sensitive and specific detection of aspergillus pathogens in vitro and in vivo. A specific two-step PCR assay for the rapid detection of the aspergillus species in blood samples improves early diagnosis for systemic aspergillosis and helps us to make decision for antifungal therapy.