Simple DNA PCR-Based Lab Test to Enable Personalized Treatment of Bacterial Vaginosis

By LabMedica International staff writers
Posted on 01 Apr 2025

Image: The DNA PCR-based lab test can rule out metronidazole treatment for BV based on highly resistant strains (Photo courtesy of Drexel University)

Approximately one in three women aged 14-49 in the United States will experience bacterial vaginosis (BV), a vaginal bacterial imbalance, at some point in their lives. Around 50% of BV cases do not present any noticeable symptoms, which leads to many individuals not seeking treatment. While about 30% of BV cases resolve on their own, untreated infections can increase the risk of sexually transmitted infections, complications during pregnancy, and other issues caused by inflammation in the mucosal lining of the reproductive tract, negatively affecting quality of life. Furthermore, over half of the patients who seek treatment with the first-line antibiotic metronidazole do not respond to it, resulting in recurrence. To address this, researchers have now developed a simple DNA PCR-based lab test, which provides a more detailed genetic analysis of the primary bacterial species responsible for the infection, enabling clinicians to prescribe the most appropriate medication for each patient.

The main bacterial pathogens responsible for BV belong to a group of closely related species previously referred to as Gardnerella vaginalis. Earlier studies by Drexel University researchers (Philadelphia, PA, USA) revealed that this group consists of multiple species. In their current research, published in Genome Medicine, the team expanded this "family tree" significantly. By using genome sequencing and genomic analysis on 129 Gardnerella species genomes, the team conducted a detailed study that uncovered much greater diversity within the group. They identified 11 distinct genospecies, which belong to several major clades, or groupings.

The researchers found that two of these clades, made up of five genospecies, are entirely resistant to metronidazole but can be effectively treated with clindamycin. Both antibiotics are commonly prescribed for a week and can be administered either vaginally or orally. The PCR test developed by the researchers can accurately identify these strains, distinguishing those that are highly resistant to metronidazole. The team has applied for a patent for the test. To make it widely available, a commercial lab would need to offer the service to patients, and demand from patients and patient advocacy groups may help drive its availability. Currently, the test can help avoid ineffective metronidazole treatment by identifying resistant strains, and the team plans to enhance its capabilities to also detect strains with lower resistance to metronidazole.

“If this test becomes available to patients, they can avoid taking the wrong antibiotic, avoiding additional potential side effects and financial costs,” said lead author Katherine Innamorati, PhD, an instructor in Drexel University College of Medicine. “Faster treatment and better antibiotic stewardship is especially important for patients who may need to take multiple courses of antibiotics to fully eliminate the infection.”