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External quality assessment program for Chlamydia trachomatis diagnostic testing by nucleic acid amplification
Sally Land1, Sepehr Tabrizi, Anthony Gust
1National Serology Reference Laboratory, Australia, St Vincent's Institute of Medical Research, Fitzroy, VIC 3065, Australia. sally@nrl.gov.au
Journal of Clinical Microbiology
|August 1, 2002
Summary
This study compared two Chlamydia trachomatis diagnostic tests in Australian labs. Roche Amplicor PCR showed higher sensitivity for antigen detection at low levels, but single-sample testing reduced sensitivity for both assays.
Area of Science:
- Clinical Microbiology
- Diagnostic Assays
- Molecular Diagnostics
Background:
- Accurate detection of Chlamydia trachomatis is crucial for public health.
- External quality assessment (EQA) is vital for validating diagnostic laboratory performance.
- Comparing different nucleic acid amplification tests (NAATs) aids in selecting optimal diagnostic tools.
Purpose of the Study:
- To evaluate the performance of two Chlamydia trachomatis diagnostic assays in Australian diagnostic laboratories.
- To compare the sensitivity and specificity of the Roche Amplicor Chlamydia trachomatis test (R-PCR) and the Abbott LCx Chlamydia trachomatis assay (A-ligase chain reaction [LCR]).
- To assess the impact of sample type and testing strategy on diagnostic accuracy.
Main Methods:
- Fifty-seven Australian diagnostic laboratories participated in the study.
- Laboratories tested two EQA panels using either R-PCR or A-LCR.
- Panel samples included normal urine spiked with C. trachomatis antigen and clinical urine specimens.
Main Results:
- No significant differences were observed between laboratories or assays in detecting C. trachomatis-positive clinical samples.
- R-PCR demonstrated superior sensitivity compared to A-LCR specifically at the lower limit of detection for C. trachomatis antigen.
- Single-sample testing was found to decrease the sensitivity of both assays.
- Inter-laboratory variation was noted in the detection of nucleic acid amplification inhibitors.
Conclusions:
- Both R-PCR and A-LCR are comparable for detecting C. trachomatis in clinical urine samples.
- R-PCR offers an advantage in detecting low levels of C. trachomatis antigen.
- Laboratory practices, such as single-sample testing and inhibitor management, can influence diagnostic test performance.
