Comparing mail-in self-collected specimens sent via United States Postal Service versus clinic-collected specimens for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in extra-genital sites

PLoS One. 2017 Dec 14;12(12):e0189515. doi: 10.1371/journal.pone.0189515. eCollection 2017.


Objectives: To evaluate the concordance between clinic-collected extra-genital specimens and self-collected mailed-in extra-genital specimens among participants seeking sexually transmitted infection testing at a free clinic in Hollywood, CA.

Methods: A convenience sample of 210 men who have sex with men were enrolled between February 29, 2016 and December 21, 2016 and received mail-in testing kits for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG). All testing was performed using the GeneXpert® CT/NG (Cepheid, Sunnyvale, CA).

Results: From the 210 mail-in kits distributed, 149 mail-in kits (71.0%) were returned to the laboratory, resulting in 145 pairs (clinic-collected and mail-in) of rectal test results and 148 pairs of pharyngeal test results for both CT and NG detection. The concordance was 95.0% for all CT rectal tests, 99.3% for all CT pharyngeal tests, 95.7% for all NG rectal tests, and 97.2% for all NG pharyngeal tests.

Conclusion: Roughly two-thirds of mail-in test kits were returned and concordance was generally high, however more than one-third of positive results were missed in mail-in samples. The prevalence of potential false-negative results among mail-in samples warrants caution when implementing mail-in STI testing strategies.

Publication types

  • Comparative Study

MeSH terms

  • Chlamydia trachomatis / isolation & purification*
  • Homosexuality, Male*
  • Humans
  • Male
  • Neisseria gonorrhoeae / isolation & purification*
  • Pharynx / microbiology*
  • Postal Service*
  • Rectum / microbiology*
  • Sexually Transmitted Diseases / diagnosis*
  • Sexually Transmitted Diseases / microbiology
  • Specimen Handling*
  • United States

Grant support

This work was supported from funding from National Institute of Allergy and Infectious Diseases Grant number: T32AI007384 ( to CCB and Cepheid provided all testing materials ( The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.