ab2002

Evaluation of Amplicor^® Chlamydia PCR and LCX^® Chlamydia LCR to detect Chlamydia trachomatis in synovial fluid

J.G. Kuipers, J. Andresen, L. Köhler, S. Schnarr, N. Putschky, H. Zeidler, J. Wollenhaupt

Division of Rheumatology, Department of Internal Medicine, Medical School Hannover, Hannover, Germany.

ABSTRACT
Objectives
PCR has been successfully used in research for the detection of C. trachomatis DNA in synovial samples. However, each research laboratory has developed its own PCR, making inter-laboratory comparisons difficult. To allow for standardization we evaluated two commercially available amplification systems originally designed for the examination of urogenital samples (Roche Amplicor^® Chlamydia PCR and Abbott LCX^® Chlamydia LCR), using them to analyse spiked and clinical synovial fluid (SF) samples from reactive arthritis (ReA), undifferentiated arthritis (UA), and rheumatoid arthritis (RA) patients. We compared their sensitivity in assays of clinical SF samples with our in-house developed C. trachomatis specific nested PCR.

Methods
SF was spiked with purified C. trachomatis elementary bodies (EB) and analyzed by the commercial assays. Clinical SF samples from ReA (n=21), UA (n=79) and RA (n=50) patients were examined by the two commercial assays and our in-house PCR.

Results
Using SF samples spiked with defined numbers of C. trachomatis EB, the sensitivity of the commercial tests was high and similar to published PCR sensitivity. In clinical SF specimens the commercial assays was also able to detect CT; however, the in-house PCR was more sensitive. Out of 10 PCR-positive SF samples Amplicor tested positive in only 4/10 and LCX in only 3/10. The in-house PCR detected chlamydial DNA in synovial fluid from 5/21 ReA (24%), 5/79 UA (6%) and in none of the 50 RA patients.

Conclusion
Commercial amplification assays allow the detection of C. trachomatis in clinical specimens, although with a lower sensitivity than optimized PCR. Potential explanations are discussed.

Key words
Chlamydia trachomatis, PCR, LCR, transcription mediated amplification, synovial fluid, reactive arthritis.

This work was supported by grants of the Federal Ministry of education and research (BMBF: 01 VM 9395 to JGK & JW and 01 GI 9950 to JGK). Reagents for commercial amplifications assays were kindly provided by the manufacturers.
Please address correspondence to: Jürgen Wollenhaupt, MD, Division of Rheumatology and Clinical Immunology, Allgemeines Krankenhaus Eilbek, Friedrichsberger Str. 60, D-22081 Hamburg, Germany.