Is Supplementary Bead Beating for DNA Extraction from Nematode Eggs by Use of the NucliSENS easyMag Protocol Necessary?

Recent studies have demonstrated the effectiveness and appli-cability of PCR-based methods for the detection of intestinal helminths in stool samples (1–5); however, successful DNA ex-traction is essential. We compared DNA extractions using NucliSENS easyMag, with and without a preceding step of supple-mentary bead beating, from eggs of parasitic nematodes by spik-ing equal portions of Dientamoeba fragilis-positive stool samples with eggs of Ascaris suum and Trichuris trichiura. A. suum eggs isolated from pig feces were washed three times in phosphate-buffered saline (PBS), and 0, 1, 3, 5, and 20 eggs were spiked into triplicate samples of 100 mg feces (Table 1). To each sample, we either added no beads or 150 to 200 mg of one of three different types of beads: 0.5-mm glass beads (CoBio, Copenhagen, Den-mark), 0.15-mm garnet beads (CoBio, Copenhagen, Denmark), or 0.1-mm zirconium beads (Techtum Lab AB, Umeå, Sweden). The samples were then either vortexed on a Vortex-Genie 2 for 1