Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.
Keywords: Chlamydia trachomatis; Epithelial cells; External Quality Assessment; Polymerase chain reaction; Quality control.