Patrick Bafuma is back to interview Janelle Bludorn for this installment of the EM ID podcast series. This time they talk about testing for two of the most common sexually transmitted infections (STIs), Gonorrhea and Chlamydia (GC/C).
Check out the show notes for their outline and citations, but the citations are also linked at the bottom of this post. It will include some numbers that are beneficial to know, as well.
First catch urine is the first 5-20ml of urine. Frequently thought of as a "dirty catch" (versus the traditional "clean catch" urine that does not collect this portion of urine) this urine is good for nucleic acid amplification tests (NAAT) for GC/C. However, there should be no urination in the hour prior for best results.
First void is the first urination of the day and is not necessary for NAAT for GC/C.
How does NAAT for GC/C from urine compare to swabs? Urinary testing for men is great but for women the urinary testing for GC/C has a lower sensitivity but still holds great specificity compared to swabs.
Does this mean that clinicians need to be swabbing all women? Not necessarily as self swabs for women can be effective.
Do you need a test of cure 3-4 weeks after treatment? Usually not, unless you think the did not adhere to therapy, have persistent symptoms, or suspicion for a reinfection. However, CDC recommends retesting at 3 months as tests have have a false positive in this timeframe from the recent nucleic acids.
A big thanks again to both Patrick Bafuma and Janelle Bludorn for their involvement in the podcast.
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Meyer T. Diagnostic Procedures to Detect Chlamydia trachomatis Infections. Microorganisms. 2016;4(3):25. Published 2016 Aug 5. doi:10.3390/microorganisms4030025
Schachter J, Chernesky MA, Willis DE, et al. Vaginal swabs are the specimens of choice when screening for Chlamydia trachomatis and Neisseria gonorrhoeae: results from a multicenter evaluation of the APTIMA assays for both infections. Sex Transm Dis 2005;32:725–8.
Mangin D, Murdoch D, Wells JE, et al. Chlamydia trachomatis testing sensitivity in midstream compared with first-void urine specimens. Ann Fam Med. 2012;10(1):50-3.
2015 Sexually Transmitted Diseases Treatment Guidelines (2015)
Recommendations for the Laboratory-Based Detection of Chlamydia trachomatis and Neisseria gonorrhoeae — 2014. Recommendations and Reports. CDC Morbidity and Mortality Weekly Report. March 14, 2014 / 63(RR02);1-19
Evidence Summary on GC/C:
Urinary Symptoms in Adolescent Females: STI or UTI? Jill S.HuppertM.D., M.P.H. FrankBiroM.D. DongmeiLanM.S. Joel E.MortensenPh.D. JenniferReedM.D. Gail B.SlapM.D., M.S.
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