Background Bacterial vaginosis (BV) is characterized by low-Lactobacilli and increased anaerobes. BV can be determined by clinical assessment (Amsel’s criteria) or microscopy (Nugent scoring); molecular methods are also under study. We investigated concordance between Amsel-BV, Nugent-BV and low-Lactobacillus vaginal microbiota identified via 16S rRNA gene sequencing.

Methods Vaginal swabs and clinical data were collected from women enrolled in a longitudinal study. Amsel’s criteria were determined clinically and Nugent scoring (Nugent-BV=7–10, intermediate=4–6) was determined by microscopy. Vaginal microbiota were characterized using 16S rRNA gene sequencing and categorized into 7 community state types (CSTs): 4 dominated by Lactobacillus spp. (CST I, II, III and V), and 3 by Streptococcus spp. (CST VI), Bifidobacterium spp. (CST VII), or a variety of anaerobes (CST IV).

Results 110 samples, ∼10 from each CST, were selected. 5.5% (n=6) had Amsel-BV, 32.7% (n=36) Nugent-BV, and 36.4% (n=40) had low-Lactobacillus CSTs (IV, VI, VII); 8.2% had symptoms. Among Amsel-BV samples, 83.3% had Nugent-BV, 16.7% had intermediate Nugent score and all were CST IV. 86.1% of women with Nugent-BV and 85% of women with low-Lactobacillus CSTs did not have Amsel-BV. 22.2% of those with Nugent-BV did not have low-Lactobacillus CSTs; of these 50% were CST III (L. iners-dominated). 46.7% of CST-III had a vaginal pH ≥4.5, and 13.3% had a Nugent BV score. 22 samples had a vaginal pH≥4.5 and a normal Nugent score: 45.5% were in CST III, 9.1% in low-Lactobacillus CSTs. 30.6% women with Nugent-BV had a vaginal pH <4.5; of these 45.5% were in CST IV.

Conclusion Nugent score and low-Lactobacillus CST were concordant. L. iners-dominated CSTs often had normal Nugent scores and high pH. Among mostly asymptomatic women, a large proportion with low-Lactobacillus CSTs did not have Amsel-BV. Future studies assessing long term clinical outcomes will be needed to determine whether molecular methods provide added actionable or prognostic information.

Disclosure No significant relationships.