Clinical utility of nucleic acid amplification testing for detection of sexually transmitted infections in women with symptomatic bacterial vaginosis and vulvovaginal candidiasis identified by conventional versus molecular diagnoses

ABSTRACT Numerous studies describe increased rates of sexually transmitted infections (STIs) in women with symptomatic vaginitis from various causes. We present a comparative analysis of the diagnostic utility of STI nucleic acid amplification testing (NAAT) for Trichomonas vaginalis (TV), Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma genitalium (MG) in 1,039 women with symptomatic vaginitis, including 823 women diagnosed with bacterial vaginosis (BV) and/or vulvovaginal candidiasis (VVC) by in-office health care provider (HCP) clinical assessment, conventional laboratory methods (Nugent Score/Amsel Criteria/culture), or BV- and VVC-NAAT methods. Among 508 women with a conventional laboratory BV diagnosis, significantly more STIs were detected in women with a positive BV-NAAT result (147/154, 95.5%) compared to women with HCP diagnosis of BV (134/154, 87.0%; P = 0.0408). For women with a culture-positive VVC diagnosis, a higher STI-NAAT positivity rate correlated with a positive VVC-NAAT result (55/59, 93.2%) compared to HCP VVC diagnosis (18/59, 30.5%), although this difference was not significant. A positive vs negative BV-NAAT result had a significantly higher relative risk for any STI infection (RR: 1.85; 95% confidence interval [CI] 1.43–2.39, P < 0.0001), while relative risks for STI-NAAT positive infections were not elevated significantly in VVC. Finally, STI NAAT positivity rates were higher in women with positive BV/VVC NAAT vaginitis diagnoses compared to women diagnosed with BV/VVC by conventional clinician empirical diagnosis. These results indicate combined molecular testing for STIs, and BV/VVC has improved diagnostic yield compared to conventional laboratory methods or traditional HCP assessment for these disorders. IMPORTANCE An all-molecular (nucleic acid amplification test [NAAT]-based) approach to vaginitis and sexually transmitted infection (STI) testing of vaginal swabs from women with symptomatic vaginitis provides optimal STI case finding comparable to using STI NAATs after traditional lab-based methods for vaginitis diagnosis and better than using STI NAATs following a clinician’s assessment for vaginitis diagnosis. This study demonstrates that a combined molecular testing strategy to identify the causes of vaginitis and STIs can improve risk stratification, support guideline-aligned STI testing, help clinicians provide the most appropriate and comprehensive care, and streamline clinical and laboratory workflows using a single specimen and single test method (NAAT).