Clinical Evaluation of the Alinity m STI Multiplex PCR Assay

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are routinely tested and reported; however, Trichomonas vaginalis (TV) is the most common sexually transmitted infection (STI) in the United States and the prevalence of Mycoplasma genitalium (MG) infections is likely higher than estimated. We examined the clinical performance of the Alinity m STI assay for detection and surveillance of CT/NG/TV/MG in urine specimens from patients at a large academic medical center.

Urine specimen from 198 patients was tested in this evaluation. Alinity m STI and Aptima Combo 2 CT/NG and TV assay (Panther System) results were compared, with discrepant results run on the cobas 6800 CT/NG, TV/MG assays. Analyzer turnaround times, time from loading the specimen on the analyzer to results reporting, were determined for Alinity m and Panther systems.

Overall percent agreements of the Alinity m in comparison with the Aptima and cobas assays for CT, NG, TV, and MG were 99.5% (97.2%, 99.9%), 99.5% (97.2%, 99.9%), 98.4% (95.5%, 99.5%), and 86.4% (66.7%, 95.3), respectively. There were 5 discrepant samples (CT, 1; NG, 1; TV, 3) between the Alinity m and the Aptima assays, and 3 MG discrepant samples between the Alinity m STI and cobas 6800. Two of the 5 Aptima and Alinity m discrepant samples were resolved as they yielded similar results on both Alinity m and cobas 6800. TV and MG infections comprised 54% of the positive samples and were more often asymptomatic than CT and NG infections. Analyzer turnaround time was 3 hours 25 minutes for the Aptima CT/NG, 3 hours 25 minutes for Aptima TV, and 1 hour 55 minutes for Alinity m STI assay.

The Alinity m STI assay allows for fast and simultaneous detection of the 4 major STI pathogens, which can facilitate surveillance and provide accurate results to help clinicians diagnose for initiation of appropriate treatment.