Bacterial vaginosis (BV) is an enigmatic disease of unknown origin that affects a large percentage of women. The vaginal microbiota of women with BV is associated with serious sequelae, including abnormal pregnancies. The etiology of BV is not fully understood, however, it has been suggested that it is transmissible, and that G. vaginalis may be an etiological agent. Studies using enzymatic assays to define G. vaginalis biotypes, as well as more recent genomic comparisons of G. vaginalis isolates from symptomatic and asymptomatic women, suggest that particular G. vaginalis strains may play a key role in the pathogenesis of BV.
To explore G. vaginalis diversity, distribution and sexual transmission, we developed a Shannon entropy-based method to analyze low-level sequence variation in 65,710 G. vaginalis 16S rRNA gene segments that were PCR-amplified from vaginal samples of 53 monogamous women and from urethral and penile skin samples of their male partners. We observed a high degree of low-level diversity among G. vaginalis sequences with a total of 46 unique sequence variants (oligotypes), and also found strong correlations of these oligotypes between sexual partners. Even though Gram stain-defined normal and some Gram stain-defined intermediate oligotype profiles clustered together in UniFrac analysis, no single G. vaginalis oligotype was found to be specific to BV or normal vaginal samples.
This study describes a novel method for investigating G. vaginalis diversity at a low level of taxonomic discrimination. The findings support cultivation-based studies that indicate sexual partners harbor the same strains of G. vaginalis. This study also highlights the fact that a few, reproducible nucleotide variations within the 16S rRNA gene can reveal clinical or epidemiological associations that would be missed by genus-level or species-level categorization of 16S rRNA data.
Citation: Eren AM, Zozaya M, Taylor CM, Dowd SE, Martin DH, Ferris MJ (2011) Exploring the Diversity of Gardnerella vaginalis in the Genitourinary Tract Microbiota of Monogamous Couples Through Subtle Nucleotide Variation. PLoS ONE 6(10): e26732. https://doi.org/10.1371/journal.pone.0026732
Editor: Jacques Ravel, Institute for Genome Sciences, University of Maryland School of Medicine, United States of America
Received: May 11, 2011; Accepted: October 3, 2011; Published: October 25, 2011
Copyright: © 2011 Eren et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work is supported by funding from the Research Institute for Children in New Orleans and NIH grant 5RO1AI79071-2. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
As a group, bacteria are the most genetically diverse and abundant life form on Earth . In fact the human body is home to a diverse assemblage of bacteria that colonize the gastrointestinal tract, oral cavity, skin, airway passages and genitourinary system . Culture-independent surveys estimate that the human gut alone is home to 40,000 bacterial species  and it is estimated that the number of bacterial cells in the human body is ten-fold greater than the number of eukaryotic cells that comprise the human body , . Humans depend on a symbiotic relationship with bacteria to extract nutrients from food and for normal immune system development –. On the other hand, adverse medical conditions are also associated with changes in the composition and relative abundance of our bacterial microbiota.
One of the most well studied medical conditions associated with a change in the human microbiota is bacterial vaginosis (BV). BV is a common vaginal disorder and symptoms often include vaginal discharge, pruritis, and odor. The microbiology of BV is characterized by a drastic reduction in the conc