The Performance of Quantitative Real-Time Polymerase Chain Reaction and Galactomannan for Invasive Fungal Infections in Patients with Hematologic Malignancies

Invasive fungal infections (IFIs) remain a major cause of morbidity and mortality in immunocompromised patients, ranging between 60%-90%, especially in those patients with hematological malignancies who receive induction chemotherapy or undergo hematopoietic stem cell transplantation (HSCT) [1,2]. The critical challenge is achieving an accurate and early diagnosis of IFI and selecting the appropriate antifungal therapy in order to improve the outcome of patients with this life-threatening infection. The absence of reliable, rapid, non-invasive and cost effective diagnostic procedures remains a major setback in the successful management of IFIs. Early diagnosis of invasive aspergillosis (IA) appears to be associated with an increased survival rate and better outcome [3,4]. The gold standard for definitive diagnosis requires deep tissue biopsy to obtain culture and tissue specimens for histopathology. However, this invasive procedure may not be feasible in the setting of thrombocytopenia or the critical condition of the patient. In addition, the clinical signs of infection are often nonspecific and conventional tests, such as blood culture or bronchoscopy, show very low sensitivity [5]. A systematic use of chest CT is a useful tool for diagnosis and outcome evaluation of invasive pulmonary aspergillosis [6]. Therefore, a novel noninvasive method for the diagnosis of IFIs is highly needed. Moreover, among the non-invasive molecular methods, galactomannan (GM) appears to be the most studied diagnostic marker [7,8] followed by 1-3 β-D-glucan [9] and quantitative real-time PCR (qPCR) [10-12]. All of these methods offer a promising alternative to conventional methods by reducing the time for identification and improving sensitivity. Few prospective studies of qPCR in comparison and in combination with GM have been performed in patients with HM. We, therefore, conducted this study to determine the diagnostic value of qPCR and GM in cancer patients. Methods