Use of real-time PCR as an alternative to conventional genotyping methods for the laboratory detection of lymphogranuloma venereum (LGV)

Rectal Lymphogranuloma Venereum Among Men Who Have Sex With Men: 7 Versus 21 Days Doxycycline Effectiveness

ABSTRACT

This is a retrospective study on men who have sex with men (MSM) diagnosed with rectal lymphogranuloma venereum (LGV), treated with 7 or 21 days of doxycycline between 2015 and 2022. Overall, 143 MSM were included: 58 (41%) had LGV. One hundred percent of microbiologic cure was found among MSM with symptomatic or asymptomatic LGV treated with 7 and 21 days of doxycycline.

Chlamydia trachomatis Variants Escaping Detection in the Aptima Combo 2 Assay in the United States

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.