Vaginal microbiome variances in sample groups categorized by clinical criteria of bacterial vaginosis

Abstract

BackgroundOne of the most common and recurrent vaginal infections is bacterial vaginosis (BV). The diagnosis is based on changes to the “normal” vaginal microbiome; however, the normal microbiome appears to differ according to reproductive status and ethnicity, and even among individuals within these groups. The Amsel criteria and Nugent score test are widely used for diagnosing BV; however, these tests are based on different criteria, and so may indicate distinct changes in the vaginal microbial community. Nevertheless, few studies have compared the results of these test against metagenomics analysis.MethodsVaginal flora samples from 77 participants were classified according to the Amsel criteria and Nugent score test. The microbiota composition was analyzed using 16S ribosome RNA gene amplicon sequencing. Bioinformatics analysis and multivariate statistical analysis were used to evaluate the microbial diversity and function.ResultsOnly 3 % of the participants diagnosed BV negative using the Amsel criteria (A−) were BV-positive according to the Nugent score test (N+), while over half of the BV-positive patients using the Amsel criteria (A+) were BV-negative according to the Nugent score test (N−). Thirteen genera showed significant differences in distribution among BV status defined by BV tests (e.g., A − N−, A + N− and A + N+). Variations in the four most abundant taxa, Lactobacillus, Gardnerella, Prevotella, and Escherichia, were responsible for most of this dissimilarity. Furthermore, vaginal microbial diversity differed significantly among the three groups classified by the Nugent score test (N−, N+, and intermediate flora), but not between the Amsel criteria groups. Numerous predictive microbial functions, such as bacterial chemotaxis and bacterial invasion of epithelial cells, differed significantly among multiple BV test, but not between the A− and A+ groups.ConclusionsMetagenomics analysis can greatly expand our current understanding of vaginal microbial diversity in health and disease. Metagenomics profiling may also provide more reliable diagnostic criteria for BV testing.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5284-7) contains supplementary material, which is available to authorized users.

Bacterial Vaginosis: Current Diagnostic Avenues and Future Opportunities

“…The results revealed that women with BV have a heterogeneous VMB that is not dominated by a single taxon and no species is universally present in all of BV-positive women (Srinivasan et al, 2012 ). It is supported by the findings of Chen et al ( 2018 ) that significant differences in the bacterial composition of the BV microbiome were observed among BV groups defined by Amsel's criteria or Nugent scoring.…”

“…Despite multiple molecular and genomic studies being conducted at species or microbiome level, there is no consensus on the group of bacterial species that may directly cause BV (Fethers et al, 2012 ; Srinivasan et al, 2012 ; Chen et al, 2018 ; Muzny et al, 2018 ). Srinivasan et al ( 2012 ) performed broad-range 16S ribosomal RNA (rRNA) gene PCR and pyrosequencing to describe the composition and diversity of the VMB in women with BV, diagnosed either by Amsel's criteria or Nugent scoring.…”

Vaginal Microbiota Composition Correlates Between Pap Smear Microscopy and Next Generation Sequencing and Associates to Socioeconomic Status

“…The clinical diagnosis of highly common BV and other vaginal infections relies strongly on the microscopic examination of vaginal smears or visual assessment of the vaginal discharge. The correspondence between the microscopic findings and molecular VMB analysis has been previously studied using Nugent score as a reference method 22,28,29 . Here we expand these studies by comparing the light microscopy findings of the Pap smears to VMB composition determined with 16S rRNA amplicon sequencing in asymptomatic women.…”

Understanding and interpreting community sequencing measurements of the vaginal microbiome

“…The diverse community state type (CST4) identified by community sequencing is strongly associated with bacterial vaginosis (BV), but CST4 does not always correlate to BV diagnosed by microscopy and symptoms . Community sequencing is being used to identify relationships between specific bacterial taxa and symptomatic BV, and to more precisely elucidate the role of the vaginal microbiome in preterm birth (PTB) and sexually transmitted infections (STI) . There appears to be growing agreement that low levels of L. crispatus and a diverse vaginal microbiome (CST4) are associated with higher PTB risk in some, but not all, populations of pregnant women.…”