Detection of inhibitors in matrices. PCR reactions for Entamoeba gingivalis detection with 40 pg DNA matrix from patients 1 or 2 were spiked with 100 pg DNA matrix from patient #0. For patient 2’s sample (fourth lane), a fainter band of 200 bp is observed in comparison with the second lane (spiking only) or third lane (uninhibited patient 1 sample), revealing the presence of inhibitors in this sample. A control without matrix or spiking was included (fifth lane).