One of the trends in pathogen identification is the increasing reliance on molecular methods to achieve high throughput, high sensitivity and specificity of results in clinically relevant times [2, 16] . However, low pathogen copy number, inefficient extraction and the incomplete removal of inhibitors, reduce the sensitivity and specificity of the molecular assays. Among clinical samples, stool suspensions contain a wide range of materials that have the potential to inhibit RT and/or PCR chemistries [4, 6, 8, 9, 10, 11] . Thus, it is important to develop a reliable method to determine whether inhibitors are present in nucleic acid prepared directly from stool suspensions. An appropriate internal control does not exist because of wide differences in eukaryotic and prokaryotic composition in fecal material between patients.