Testing Pooled Specimens With the Abbott Alinity m STI Assay: Four Years' Experience

The Alinity m STI assay (Abbott Molecular, Des Plaines, IL, USA) is designed for the qualitative detection of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Mycoplasma genitalium (MG), and Trichomonas vaginalis (TV) in individual collected samples. Pooled specimens are not recommended due to the high risk of inhibition.

We performed a two-part study, including a preliminary validation on 13 well-known positive samples before and after pooling, as well as a retrospective analysis of 5324 pooled specimens collected between 2021 and 2024. All samples were tested for CT/NG detection, and a subset (n = 277) for MG detection on the Alinity m STI system.

The preliminary validation showed consistent results without inhibition. Out of 5324 specimens of the retrospective analysis for CT/NG detection, 966 pooled samples (18.1%) were positive: 363 (6.8%) for CT, 479 (9.0%) for NG, and 124 (2.3%) for both CT and NG. Only 95 (1.8%) tests were completely inhibited. A total of 277 specimens were additionally tested for MG. Pooled specimens also allowed MG detection (n = 195; 70.4%) with few inhibited results (n = 3; 1.0%).

This study proves that pooled specimens are rarely inhibited and can be helpful for laboratories where the number of specimens per patient is restricted.