Then she noticed something else. The internal control spike-in (a synthetic DNA fragment added by Qiagen to track inhibition) was absent . That meant the sample hadn’t inhibited the PCR—it had overwhelmed it. The control was present but undetectable because the background DNA was so massive.
She followed the protocol robotically: add sample to the bead tube, add buffer, vortex, centrifuge, transfer to the spin column, wash twice, elute. Qiagen’s format was clean, color-coded, and satisfyingly predictable. Blue caps for lysis, green for wash, white for elution. qiagen stool kit
Someone had taken an empty Qiagen PowerFecal Pro bead tube, spiked it with a pure, unknown bacterial isolate and a trace of factory control DNA, and sent it through the clinical collection system as a real human stool sample. Then she noticed something else
But why? To test the kit’s limits? To hide a pathogen in plain sight? Or simply to see if anyone would notice? The control was present but undetectable because the