New Test May Aid in Clinical Management of Vaginitis
EXECUTIVE SUMMARY
A molecular diagnostic test that accurately distinguishes among the three most common causes of vaginitis — bacterial vaginosis, trichomoniasis, and vulvovaginal candidiasis — earned Food and Drug Administration market authorization in October 2016 for use by diagnostic laboratories. The assay is licensed to BD Diagnostics of Franklin Lakes, NJ, which markets it under the BD MAX Vaginal Panel.
- Vaginal complaints represent one of the most common reasons women seek the advice of a healthcare provider. About 33% of women of childbearing age have bacterial vaginosis, and some 75% of all adult women have had at least one yeast infection in their lifetime. Approximately 3% of women of childbearing age have trichomoniasis.
Vaginal complaints represent one of the most common reasons women seek the advice of a healthcare provider.1 Consider these numbers:
- Nearly 33% of women of childbearing age have bacterial vaginosis.
- About 75% of all adult women have had at least one yeast infection in their lifetime.
- Approximately 3% of women of childbearing age have trichomoniasis.2,3
A molecular diagnostic test that accurately distinguishes among the three most common causes of vaginitis — bacterial vaginosis (BV), trichomoniasis (TV), and vulvovaginal candidiasis (VVC) — earned Food and Drug Administration market authorization in October 2016 for use by diagnostic laboratories. The assay is licensed to BD Diagnostics of Franklin Lakes, NJ, which markets it under the BD MAX Vaginal Panel.
Traditional methods used to detect vaginitis can be challenging due to the presence of many interfering substances in specimens, the large number of mixed infections, and the subjectivity of such methods, says Mark Martens, MD, FACOG, chair of the obstetrics and gynecology department at the Jersey Shore University Medical Center in Neptune, NJ.
“A multiplex microbiome-based real-time PCR (polymerase chain reaction) assay has the potential to help clinicians improve patient management and help laboratories increase workflow efficiency,” said Martens in an announcement of the test authorization.
Check Published Data
The new test first uses a real-time PCR to amplify large amounts of specific DNA sequences from the three most common causes of vaginitis from patient samples. It then reads either a positive or a negative result based on whether enough DNA is present to indicate infection.
Just-published data on the new assay indicate it is as accurate as and more objective than traditional laboratory tests, say researchers.4
To conduct the study, researchers used PCR to amplify and test for the DNA of Trichomonas vaginalis, six bacteria species, and six species of yeast. They collected vaginal swabs from 1,740 symptomatic women with typical symptoms of vaginitis, including itching and burning. Patients in the study ranged in age from 18-81 years, and were of varied educational status and ethnic backgrounds. Four vaginal swabs were collected from each patient: two for use in traditional lab testing, one for use with the new molecular test, and one for use with a separate comparative genetic method used to validate the results for discrepancy analysis purposes.
To perform the molecular test, scientists prepared the samples and added them to a cartridge equipped with all the reagents needed for PCR. They then inserted the cartridge into the BD MAX System, a real-time PCR platform that looks at the genetic sequences and issues a report for each of the three microbes. These results then were compared with results from the traditional diagnostic tools and the alternate genetic test.
Data indicate that the prevalence of bacterial vaginosis was positive in 37.3% of patients according to the traditional methods, and 36.1% in the molecular method; 14.7% of cases were found positive for yeast infection by traditional methods, and 16.2% by the molecular method; and 1.5% of patients tested positive for trichomonas using the traditional method, while 1.6% were found positive using the molecular assay.2
“Overall, the disease prevalence identified by the traditional and the new molecular methods were similar,” says Charlotte Gaydos, DrPH, MPH, professor of medicine and director of the Johns Hopkins Center for the Development of Point of Care Tests for Sexually Transmitted Diseases at the Johns Hopkins University School of Medicine in Baltimore.
Tests traditionally used to distinguish among the causes of vaginitis are “archaic, quite subjective, and time-intensive,” plus call for extensive training for those interpreting the results, said Gaydos in a statement. Traditional tests called for lab personnel to grow cultures, conduct microscopic studies of cells for infection, and even perform the “whiff test” to help tease out possible causes and choose the proper treatment. The new test is objective — either the DNA of the causative agent is there or not, says Gaydos.
The new test is more expensive than traditional methods, costing around $75-$125, depending on a clinic’s existing equipment. Samples must be processed in a PCR-capable lab, which may add time if such facilities are offsite. The economic advantages of using the new test may compensate for the upfront costs, since its results can provide more accurate and detailed diagnoses, reducing repeat patient visits.
Robert Hatcher, MD, MPH, professor emeritus of gynecology and obstetrics at Emory University School of Medicine in Atlanta, suggests that whenever reproductive-age women are being screened for bacterial vaginosis, trichomoniasis, or vulvovaginal candidiasis, they also should be screened for chlamydia, the leading preventable cause of infertility in women.
REFERENCES
- Mills BB. Vaginitis: Beyond the basics. Obstet Gynecol Clin North Am 2017;44:159-177.
- Koumans EH, Sternberg M, Bruce C, et al. The prevalence of bacterial vaginosis in the United States, 2001-2004: Associations with symptoms, sexual behaviors, and reproductive health. Sex Transm Dis 2007;34:864-869.
- Centers for Disease Control and Prevention. Genital/vulvovaginal candidiasis statistics. Fact sheet. Available at: http://bit.ly/2kMEOR1. Accessed July 21, 2017.
- Gaydos CA, Beqaj S, Schwebke JR, et al. Clinical validation of a test for the diagnosis of vaginitis. Obstet Gynecol 2017;130:181-189.
A molecular diagnostic test that accurately distinguishes among the three most common causes of vaginitis — bacterial vaginosis, trichomoniasis, and vulvovaginal candidiasis — earned Food and Drug Administration market authorization in October 2016 for use by diagnostic laboratories.
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