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Abstract
Background The vaginal flora plays an important role in the defence against HIV infection. It is thus important to assess the impact on the vaginal milieu of products that are developed to protect women against HIV acquisition.
Objectives Using Real Time PCR, describe and quantify Lactobacillae spp. in healthy European women who enter microbicide phase I studies.
Methods Thirty healthy women who don't use hormones and have a regular menstrual cycle, were sampled with a COPAN flocked vaginal swab on days 7 and 21 of the cycle for a total of 5 visits. Real Time PCR was used to quantify bacterial cells for four Lactobacillus spp. at all visits.
Results L crispatus, L iners, L jensenii, and L gasseri were present at least once in 93%, 77%, 73% and 70% of women, respectively. High counts (≥8 log for L crispatus, ≥6 log for other species) were consistently present in 60%, 67%, 53%, and 53% of women. We labelled these latter women “L species-positive”. Using logistic regression we modelled the probability of belonging to this group. The temporal variation of the log counts within this group was modelled using random effects linear regression. No predictors of being “L. species-positive” for any of the studied Lactobacillae were identified. Longitudinal analysis showed that L crispatus counts were 0.22 log higher (p<0.001) and L iners counts were 0.83 log lower (p<0.001) at the end of the menstrual cycle. Furthermore, L crispatus counts decreased by 0.40 log after intercourse (PSA present) (p=0.002), while L iners (+0.73 log, p=0.033) and L gasseri (+0.58 log, p=0.052) increased see Abstract P3-S3.06 figure 1.
Log counts of bacterial cells per ml by day in the menstrual cycle: Note: Lines connect consecutive counts for individual women. Bold line is overall trend in “L. species-positive” women.
Conclusion The menstrual cycle and sexual activity have a significant effect on Lactobacillus sp. counts. This should be taken into account when assessing safety of products in HIV prevention trials.