A longitudinal analysis of the vaginal microbiota and vaginal immune mediators in women from sub-Saharan Africa

Abstract

In cross-sectional studies increased vaginal bacterial diversity has been associated with vaginal inflammation which can be detrimental for health. We describe longitudinal changes at 5 visits over 8 weeks in vaginal microbiota and immune mediators in African women. Women (N = 40) with a normal Nugent score at all visits had a stable lactobacilli dominated microbiota with prevailing Lactobacillus iners. Presence of prostate-specific antigen (proxy for recent sex) and being amenorrhoeic (due to progestin-injectable use), but not recent vaginal cleansing, were significantly associated with microbiota diversity and inflammation (controlled for menstrual cycle and other confounders). Women (N = 40) with incident bacterial vaginosis (Nugent 7-10) had significantly lower concentrations of lactobacilli and higher concentrations of Gardnerella vaginalis, Atopobium vaginae, and Prevotella bivia, at the incident visit and when concentrations of proinflammatory cytokines (IL-1β, IL-12p70) were increased and IP-10 and elafin were decreased. A higher 'composite-qPCR vaginal-health-score' was directly associated with decreased concentrations of proinflammatory cytokines (IL-1α, IL-8, IL-12(p70)) and increased IP-10. This longitudinal study confirms the inflammatory nature of vaginal dysbiosis and its association with recent vaginal sex and progestin-injectable use. A potential role for proinflammatory mediators and IP-10 in combination with the vaginal-health-score as predictive biomarkers for vaginal dysbiosis merits further investigation.

Figure 1

Presence/absence and concentration of vaginal microbiota bacteria over the eight week study period in women with a Nugent score of 0–3 throughout. Each box depicts one visit for a particular woman. The shading of the box indicates the concentration (in log₁₀ geq/ml) of each taxon with darker colours depicting a higher concentration. If the taxon was absent, the box is white.

Figure 2

Frequency of vaginal microbiota presence over the eight week study period in women with a Nugent score of 0–3 throughout. Data in Y-axis are % of women. Sporadically present: present at 25% or fewer visits; regularly present: present at 26–74% of visits; consistently present: present at 75% or more visits.

Figure 3

Presence/absence and concentration of vaginal microbiota over the eight week study period in women with incident BV (Nugent 7–10). Each box depicts one visit for a particular woman. The shading of the box indicates the concentration level (in log₁₀ geq/ml) of each taxon with darker colours depicting a higher concentration. If the species was absent the box is white. Boxes bordered by a red line are the first BV visit for that woman. Boxes in yellow denote visits with an intermediate Nugent score of 4–6 if present before development of BV.