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Clinical sciences poster session 1: and related syndromes
P3-S1.32 A validation study of the Gen-Probe APTIMA Combo2 (AC2) assay for detecting Chlamydia trachomatis and Neisseria gonorrhoeae in dry swabs
  1. L Cosentino1,
  2. J R Schwebke2,
  3. M M Hobbs3,
  4. S L Hillier4
  1. 1Magee Womens Research Institute, Pittsburgh, USA
  2. 2University of Alabama, Birmingham, USA
  3. 3University of North Carolina, Chapel Hill, USA
  4. 4University of Pittsburgh, Magee Womens Research Institute, Pittsburgh, USA


Background Vaginal swabs are an optimal specimen for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC). The Gen-Probe Aptima system (Aptima) requires use of a sample transport media, whereas the Becton Dickinson ProbeTec ET System (Probetec) can utilise dry swabs. The use of dry swabs allows for collection of STD test samples at non-clinical testing venues.

Methods Swabs were collected from 180 sexually active women aged 15–25 years, who had asymptomatic BV and two or more risk factors for STDs. The participants received home vaginal swab self-collection kits for BV and STD testing. Participants mailed the kits directly to the lab. Probetec swabs were tested within 14 days of collection. A dry transport swab was placed into an Aptima vaginal swab collection tube, generally within 14 days of collection and stored at −80°C. Aptima swabs were thawed and tested in batches. Specimens with discordant results in the two nucleic acid amplification test systems were retested with both systems.

Results There were 58 women (32%) positive for GC and 62 (34%) positive for CT. The level of agreement between the Aptima and Probetec systems was higher for CT (176/180, 98%) than for GC (171/180, 95%). Of the 13 samples with discordant results, five were resolved with repeat testing. All eight remaining samples had discordant GC results: seven were Probetec positive, Aptima negative and one was Probetec negative, Aptima positive.

Conclusions Vaginal swabs tested in the Aptima system were equivalent to Probetec in detecting CT but were less sensitive for the detection of GC. Dry swabs cannot be recommended for detection of GC from vaginal swabs using the Aptima system.

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