Chlamydia trachomatis Variants Escaping Detection in the Aptima Combo 2 Assay in the United States. Issue 6 (16th June 2022)

• Record Type: Journal Article
• Authors: Katz, Samantha S.; Danavall, Damien C.; Morris, Monica R.; Herrod, Bridgett P.; Dale, Suzanne E.; Nye, Melinda B.; Kersh, Ellen N.; Kirkcaldy, Robert D.; Raphael, Brian H.
• Is Part Of: Sexually transmitted diseases. Volume 49:Issue 6(2022)
• Page Start: 448
• Page End: 452
• Publication Date: 2022-06-16
• Subjects: Sexually transmitted diseases -- Periodicals; Sexual health -- Periodicals; 616.951005
• DOI: 10.1097/OLQ.0000000000001617
• Languages: English
• ISSNs: 0148-5717

Abstract

Abstract : Chlamydia trachomatis diagnostic-escape variants were detected in the United States using a redesigned Aptima Combo 2 assay, which also correctly identified specimens previously identified as false negative or equivocal. Abstract : Background: The Aptima Combo 2 (AC2) assay manufactured by Hologic, Inc., detects Neisseria gonorrhoeae and/or Chlamydia trachomatis (CT) in urogenital and extragenital specimens by targeting either a 16S rRNA ( N. gonorrhoeae ) or 23S rRNA (CT) region. In 2019, a mutation (C1515T) in the 23S rRNA region was reported to cause false-negative/equivocal results in specimens collected in Finland. Specimens containing this variant (Fl-nvCT) were also discovered internationally. Working with specimens submitted to a large commercial laboratory, we sought to determine if this variant was also present in the United States. Methods: A subset (n = 401) of specimens tested with the AC2 assay collected during a 5-week period in late 2019/early 2020 were evaluated using an updated AC2 assay. Results: Although the FI-nvCT variant was not detected within this specimen panel, 2 CT variants containing 23S rRNA mutations (A1518G, G1526A) were identified. The updated AC2 assay targeting an additional region of the 23S rRNA detected both of these variants. A retrospective study of >18 million AC2 results tested between 2018 and 2019 did not display a decrease in CT positivity. Conclusions: Although we did not detect the Fl-nvCT variant among US specimens, we show evidence that the low occurrence of similar diagnostic-escape mutants can be detected with an updated AC2 assay using multiple 23S rRNA targets.