that a G. vaginalis isolate from a GS-defined BV patient, differed from an isolate from a GS-defined normal patient by having the capacity to form tightly adherent biofilms on vaginal epithelial cells . Genomic analysis of three G. vaginalis strains, two isolated from GS-defined BV patients and one from a GS-defined normal patient, showed that the GS-defined BV-associated strains produce proteins that are not found in the strain isolated from the GS-defined normal patient . Moreover, another study of three G. vaginalis isolates revealed that two of the three isolates were able to produce sialidase, an enzyme associated with adverse pregnancy outcome in GS-defined BV patients , .
Piot et al. introduced a way to define G. vaginalis biotypes using enzymatic assays for lipase, hippurate hydrolysis and β-galactosidase activities , and defined eight biotypes. However, since eight (23) is the maximum number of different types that can be defined using such an approach, the results may have reached that number not because the biotyping scheme is able to distinguish among all potential strains, but because the approach reached it's limit by finding all eight possible patterns of expression among the isolates. Hence, one cannot tell from these results whether in fact there may be more biotypes. Regardless, given the great diversity in human-host microbial communities, a new approach that has the potential to distinguish more biotypes may indeed reveal more types of G. vaginalis.
We explored the diversity and sexual transmissibility of G. vaginalis by examining the sequence variation and distribution of 65,710 G. vaginalis 16S rRNA pyrosequencing reads that were PCR-amplified from vaginal samples of 35 GS-defined BV, 5 GS-defined intermediate and 8 GS-defined normal women and from penile skin and urethral samples obtained from their male sexual partners. To identify high quality G. vaginalis sequences in our pyrosequencing libraries, and to minimize variation due to pyrosequencing errors, we performed a stringent search against a local database of 3 unique, full-length G. vaginalis 16S rRNA gene sequences acquired from the Ribosomal Database Project. We used a Shannon entropy-based approach to identify nucleotide positions that exhibit a high level of variation, and concatenated these nucleotides to define a set of 46 “oligotypes”. We examined patterns in the distribution and relative abundance of these oligotypes within individual couples, as well as across genders, anatomical sampling sites, and GS-defined BV and normal microbiota.
Materials and Methods
All patients enrolled in this study signed written informed consent to their participation. The study protocol and consent form was approved by the LSU Health Sciences Center Institutional Review Board.
Sample collection and clinical measurements
53 monogamous heterosexual couples were included in this study. The couples were recruited at the New Orleans STD clinic. From these 53 couples, we obtained 157 DNA samples (2 males did not provide urethral swabs). All subjects were at least 18 years old with no history of antibiotic use in the past 28 days, and couples presented together for evaluation. A vaginal swab was collected from each woman for DNA extraction and pyrosequencing analysis of bacterial composition. A separate vaginal swab sample was collected and characterized by GS NS . The samples were designated “normal” (NS = 0–3), “intermediate” (NS = 4–6) or “BV” (NS = 7–10). Two urethral swabs and two penile skin swabs were collected from males. For penile skin samples, two sterile Copan flocked swabs were used. One was rolled with firm pressure around the circumference of the coronal sulcus and over the surface of the glans penis. The second one was rolled with firm pressure all over the penile shaft. Urethral swabs were collected by inserting a sterile swab into the urethral meatus and rotating back and forth for 2–3 seconds. The first urethral swab was rolled on a slide and stained with a modified methylene blue stain to evaluate for the presence of urethritis. The penile s