Can mailed swab samples be dry-shipped for the detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis by nucleic acid amplification tests?

Abstract

Background Dry-shipped and mailed vaginal swabs collected at home have been used in research studies for the detection of C. trachomatis (CT), N. gonorrhoeae (GC), and Trichomonas vaginalis (TV) by nucleic acid amplification tests (NAATs) in screening programs. A verification study was performed to compare the limit of detection of CT, GC, and TV on swabs that were dry-shipped to paired swabs that were wet-shipped in transport media through the U.S. mail. Methods The Centers for Disease Control and Prevention prepared inocula in sterile water to mock simulated urogenital swabs with high to low concentrations of CT and GC. Replicate swabs were inoculated with 100µl of dilutions, were dry transported or placed into commercial transport media (“wet”) for mailing for NAAT testing. The University of Alabama prepared replicate concentrations of TV, which were similarly shipped and tested by NAAT. Results All paired dry and wet swabs were detectable for CT. For GC, all paired dry and wet swabs were detectable for GC at concentrations ≥103. At 102 and 10 CFU/ml, the 10 replicate GC results were variably positive. For TV, wet and dry shipped concentrations > 102 TV/ml tested positive, while results at 10 TV/ml were negative for dry swabs. Holding replicate dry swabs at 55°C 5 days before testing did not affect results. Conclusion NAATs were able to detect CT, GC, and TV on dry transported swabs. Using NAATs for testing home-collected, urogenital swabs mailed in a dry state to a laboratory may be useful for outreach screening programs.

Stability Studies on Dry Swabs and Wet Mailed Swabs for Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Aptima Assays

“…Our results show that the RNA target detected using the ACT is very stable on dry swabs under relatively high temperatures for an extended period of time, as previous studies had demonstrated (10,11,15). These findings suggest that the combination of the dry swab and the Aptima test may be suitable for use when specimens are collected in unfavorable settings, where ambient temperatures may be high and transport difficult.…”

“…However, SOVS specimens are FDA cleared for use only when collected in a clinic setting. The ability to self-collect at home and mail in specimens could have a significant impact on sexually transmitted disease (STD) control efforts (13)(14)(15). To assess such use in screening programs, we initially performed a pilot study to determine specimen stability and monitor the shipping temperatures during transit.…”

Paper-based molecular diagnostic for Chlamydia trachomatis

“…It has been shown that self-collected samples are able to provide the same sensitivity as those samples collected in clinics. 4 In urine, the average CT load was 770 EBs per 100 μl samples for women and 1200 EBs per 100 μl for men. 5 …”

Evaluation of pooled ocular and vaginal swabs by the Cepheid GeneXpert CT/NG assay for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae compared to the GenProbe Aptima Combo 2 Assay

“…Upon arrival, dry-shipped vaginal swabs were expressed into 800 μL of 1X TE buffer pH 7.4 and split into 2 aliquots, 1 containing 200 μL and 1 containing 400 μL, then 200 μL was transferred into a vaginal APTIMA collection tube for testing (Gaydos et al, 2012; Masek et al, 2009). Vaginal swabs were tested individually by AC2 and later pooled for analysis by GeneXpert.…”