FIG. 3.

Performance of the cellular IC to monitor PCR inhibition compared to the standard IC. PCR amplifications were performed in the presence of various amounts of a crude DNA extract prepared from a GBS-negative vaginal/anal sample using the manual method. For the cellular IC, a portion of the clinical sample was spiked with 2 × 10⁴ B. atrophaeus spores before cell lysis and DNA extraction (giving the equivalent of 500 spores per PCR). For the standard IC, 60 copies of linearized plasmid were added to each PCR. Cycle threshold values from the TET-labeled IC-specific probes obtained with the different volumes of DNA extract tested are presented. Standard deviations are for three replicate tests.