Preliminary Study for Comparison of Commercial Kits for Isolation of Blastocystis sp. DNA in Stool Samples from Patients

In molecular diagnosis, the detection of protozoa in fecal samples is hampered by poor recovery of DNA and the presence of PCR inhibitors. In this regard, a reliable extraction of DNA is a key step in the molecular diagnosis of parasitic infections. Currently, there are many commercially available kits for isolation of DNA from feces. Each of these includes a method for removing PCR inhibitors from samples. The purpose of the study was to determine a suitable kit for isolating Blastocystis sp. DNA from fecal samples and then use it in PCR to detect Blastocystis sp. in the samples. Three commercially available kits were used to isolate the DNA of Blastocystis sp. using human feces samples. The study included stool samples of patients referred for routine laboratory testing for parasites. The samples in which Blastocystis sp. was detected by microscopic examination (a native lugol preparation and staining with trichrome) and cultivation in Jones' medium containing 10% horse serum were utilized. QIAamp DNA Stool Mini kit (Qiagen, Germany), ZR Fecal DNA kit (Zymo Research, USA) and ExgeneTM Stool DNA mini (GeneAll, Korea) were used for the extraction of Blastocystis DNA. The quality and purity of total genomic DNA was measured with a spectrophotometer. Specific primers were employed for the amplification of Blastocystis sp. DNA. In this study, it was observed that ExgeneTM Stool DNA mini could not detect Blastocystis sp. DNA in gel electrophoresis, while the QIAamp DNA Stool Mini kit and ZR Fecal DNA kit outperformed for isolation of DNA.