Neg Trich on VP3 but Positive NAAT? Why?

A growing body of research reveals the link between STIs and the pathogens that cause most cases of vaginitis. Over 90% of vaginitis cases result from BV, yeast, or trich- alone or in combination. But, a recent 2024 study from Schwebke et al., in the J Clinical Microbiology, found that about 1 in 5 women who presented with symptoms of vaginitis also had at least one STI…a good reminder to not just stop at a VP3 or wet mount. Additionally, women who tested positive for BV had an STI infection rate double the rate found in women who tested negative for BV. In fact, T. vaginalis (TV) and Mycoplasma genitalium (M. gen) infections were significantly associated with BV. We generally trust our tests- don’t we? Negative VP3 for trich- all clear right? Not quite. In this episode, we will highlight our real case where the VP3 test confirmed BV as the only issue in our symptomatic pregnant patient, yet the cervical NAAT collected at the same time returned positive for Trichomoniasis. Why the discrepancy? It actually is very common- and that may be a care gap. Listen in for details.

1. Schwebke JR, Nyirjesy P, Dsouza M, et al. Vaginitis and risk of sexually transmitted infections: Results from a multi-center U.S. clinical study using STI nucleic acid amplification testing. J Clin Microbiol. 2024;62(9):e0081624.

2. Peebles, K., Velloza, J., Balkus, J. E., McClelland, R. S. & Barnabas, R. V. High global burden and costs of bacterial vaginosis: a systematic review and meta-analysis. Sex. Trans. Dis. 46, 304–311 (2019).

3. Paladine HL and Desai UA. Vaginitis: Diagnosis and treatment. Am Fam Physician. 2018;97(5):321-329.