FIG. 5.

Performance comparison of both IC systems using selected GBS-positive and GBS-negative vaginal/anal samples. For both IC systems, crude DNA extracts were prepared from the selected vaginal and anal samples by using the manual or the CD-based automated DNA extraction methods. Control reactions without clinical sample were performed. For the cellular IC, a portion of each selected vaginal or anal 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 obtained from both the TET-labeled IC-specific probes (A) and the FAM-labeled GBS-specific probes (B) are presented. Selected clinical samples are as follows: samples 1 and 2, GBS-negative vaginal/anal samples; samples 3 and 4, GBS-positive vaginal/anal samples collected from heavily and lightly colonized women, respectively. The absence of cycle threshold value means that the nucleic acid target was undetectable after 45 cycles of PCR amplification.