Evaluation of the Abbott M2000 sp/rt real-time PCR on Chlamydia trachomatis and Neisseria gonorrhoeae using urine samples, and comparison with the Roche Cobas Amplicor Ctr/Ngo PCR assays

Abstract number: 1733_416

Luijt D., Schirm J.

Objectives:Chlamydia trachomatis (Ctr) and Neisseria gonorrhoeae (Ngo) are the most common micro organisms diagnosed in sexually transmitted diseases. Nowadays laboratory diagnosis of Ctr and Ngo is mainly based on molecular methods. The aim of this study was to evaluate the recently introduced ABBOTT M2000 sp/rt real-time Ctr/Ngo PCR assay in urine specimens, and to make a comparison with the ROCHE COBAS AMPLICOR (CA) Ctr/Ngo PCR test.

Methods and Materials: Dilutions of positive control stocks in urine and QCMD quality control panels were used for the analytical sensitivity testing. In addition 846 clinical urine samples were tested prospectively. Positive results of the CA Ngo assay were confirmed with a specific real-time in-house PCR using the opa gene.

Results: For both Ctr and Ngo the dilution series showed a higher sensitivity for the M2000 assay than for the CA assay. In the QCMD panels the M2000 assay had a 100% performance, whereas the CA assay missed the sample with the lowest copy number of both Ctr and Ngo. In the prospective study 5 (0.6%) samples were inhibited in the M2000 assay and 20 (2.4%) samples were inhibited in the CA assay. Of the remaining 821 urine samples 61 were positive and 749 negative for Ctr in both assays. Of the 11 discrepant samples 8 were positive with the Ctr M2000-positive/CA-negative, and 3 were Ctr CA-positive/M2000-negative. The 8 M2000-positive/CA-negative samples were all weak positive. Because of the higher analytical sensitivity of the M2000 assay these samples were presumable true Ctr positive samples. The 3 Ctr CA-positive/M2000-negative samples were all negative after retesting in the CA assay.

For Ngo 5 samples were positive and 799 samples negative in both assays. All 5 positive samples were also positive in the Ngo specific real-time confirmation assay. The other 17 discrepant samples were all positive in the CA assay but negative in the M2000 assay. All these 17 samples were negative in the real-time in-house PCR confirmation assay.

Conclusions: In conclusion, the M2000 assays for both Ctr and Ngo are sensitive and specific assays, with a very low inhibition rate. For Ngo the M2000 the assay is a more specific test than the Ngo CA assay. The ABBOTT M 2000sp/rt system is very suitable for routine diagnostic laboratories because of the automation, the high throughput, and the good specificity.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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