Application of HTB-SiHa cells transfected with a recombinant plasmid for external quality assessment of Chlamydia trachomatis PCR

The participation of laboratories in external quality assessment (EQA) programs is required for the quality assurance of nucleic acid amplification of Chlamydia trachomatis. This study aimed to construct a new quality control (QC) material applicated in EQA of C. trachomatis PCR.

A QC material-HTB-SiHa cells transfected with a recombinant plasmid containing the cryptic plasmid sequence-was constructed for C. trachomatis PCR detection, and four different panels, each consisting of 4 positive samples with serial dilution of the constructed QC material and 1 negative sample, were distributed by the National Center for Clinical Laboratories among four groups of 275, 268, 317, and 304 participants across China from 2011 through 2012. A total of eight commercial kits were used for C. trachomatis PCR detection in participants.

Nine laboratories reported false-positive results (0.9%). As the series dilution increased, the correct reporting of the data sets decreased; the lowest correct rate was 96.3% in the weakest positive samples (10(4) copies/mL). Eight laboratories reported false-positive results, and 42 laboratories reported false-negative results in the EQA detection of C. trachomatis. No significant differences were observed in the detection of the constructed C. trachomatis positive samples (97.9%, 98.5%, 100%, 98.5%; P=0.36) and negative samples (100%, 99.0%, 100%, 99.0%; P=0.764) using four commercial kits commonly used in China.

The results of the EQA study indicated that the constructed material provides a noninfectious, stable control material with sufficient volume for PCR detection of C. trachomatis.