Using PCR and Real-Time PCR (LightCycler) for Diagnosis and Follow up of Invasive Fungal Infections in Patients with Hematological Malignancies and Transplantation.

In modern medicine, for early diagnosis of infections, tests that have high specificity and sensitivity should be preferred. For this reason, especially for patients with hematological malignancies and transplantation, that have high mortality and morbidity ratios, some molecular biological techniques are coming into use today for differential diagnosis and follow up of invasive fungal infections. In the coming years it will become easier to early diagnose and also to plan optimal treatments, by using these techniques for diagnosis of fungal infections. In this study, we made fungal DNA isolation from blood samples, which were taken from patients, in immunodeficiency state, with hematological malignancies and transplantation. For polymerase chain reaction (PCR), we used universal fungal primers. By using real-time PCR samples from 20 patients, which were found positive by PCR, the amount of DNA was measured. In real-time PCR, we used Aspergillus colonies as our standard, and for this purpose, SDA petri dishes were incubated for 72 hours at 30°C and; 101-106 cfu/mL serial dilutions were made by using hemocytometry. We performed DNA isolation and PCR from these dilutions. Fungal species specific products giving one band of 500 bp, were fixed in 2% agarose gel. We measured the DNA amounts by real-time PCR by using Sybr Green I. Standard dilution series and extraction samples were studied at the same time by real-time PCR. Measurement of the DNA quantities in the separate samples, one at the time of first day and the other after 15 days were interpreted by the LightCycler system. Results of real-time PCR in these two different samples were compared; it was noted that fungal DNA was increased in 5, decreased in 6 and equivalent in 9 patients. These findings showed that real-time PCR is a new, specific and a sensitive method among the other quantitative PCR systems. This method was also quicker than the other quantitative PCR systems. Currently, the investigators prefer this method because, it gives early idea about patient condition, for early diagnosis of infections and treatment patients who are under risk of some kind of infection, and for follow up treatment results. Additionally for diagnosis of fungal infections serial samples in PCR, together with other conventional diagnostic methods, should used.