Longitudinal Study of the Dynamics of Vaginal Microflora during Two Consecutive Menstrual Cycles

Background Although the vaginal microflora (VMF) has been well studied, information on the fluctuation of the different bacterial species throughout the menstrual cycle and the information on events preceding the presence of disturbed VMF is still very limited. Documenting the dynamics of the VMF during the menstrual cycle might provide better insights. In this study, we assessed the presence of different Lactobacillus species in relation to the BV associated species during the menstrual cycle, assessed the influence of the menstrual cycle on the different categories of vaginal microflora and assessed possible causes, such as menstruation and sexual intercourse, of VMF disturbance. To our knowledge, this is the first longitudinal study in which swabs and Gram stains were available for each day of two consecutive menstrual cycles, whereby 8 grades of VMF were distinguished by Gram stain analysis, and whereby the swabs were cultured every 7th day and identification of the bacterial isolates was carried out with a molecular technique. Methods Self-collected vaginal swabs were obtained daily from 17 non pregnant, menarchal volunteers, and used for daily Gram staining and weekly culture. Bacterial isolates were identified with tDNA-PCR and 16 S rRNA gene sequencing. Results Nine women presented with predominantly normal VMF and the 8 others had predominantly disturbed VMF. The overall VMF of each volunteer was characteristic and rather stable. Menses and antimicrobials were the major disturbing factors of the VMF. Disturbances were always accompanied by a rise in Gram positive cocci, which also appeared to be a significant group within the VMF in general. Conclusions We observed a huge interindividual variability of predominantly stable VMF types. The importance of Gram positive cocci in VMF is underestimated. L. crispatus was the species that was most negatively affected by the menses, whereas the presence of the other lactobacilli was less variable.


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Gram stain Vaginal pH Culture Nugent et al. (1991) [9] Two cycles (8 weeks) Each day What should be regarded as normal vaginal flora?
Is the finding of BV, Candida spp., M. hominis, U. urealyticum, or ,B-haemolytic streptococci on a single occasion in asymptomatic women significant?
Is the finding of normal VMF on a single occasion in symptomatic women significant?" Keane et al. (1997) [ pH values did not always rise throughout the menses and elevated values were also found in groups A and C which did not correspond to the presence or subsequent development of abnormal VMF.
In group A and C there was a trend for the numbers of Lactobacilli to fluctuate throughout the MC.
The use of OC did not appear to influence the Lactobacilli concentration in group A.
GPC tended to appear mostly at the beginning of the menstrual cycle in groups A and C. 10 days -10 months Not specified Whether antifungal treatment was taken or not, in many cases candida arose, to be followed by BV.

Authors
BV developed within 48 h of unprotected intercourse on only one occasion, and resolved after intercourse on 9 occasions.
In most of the women BV resolved after 3 to 4 days' treatment. Usually an intermediate VMF was present transiently. Relapse could occur within a few days.
BV arose just before menstruation, or during menstruation more often than midcycle; a time when it was more likely to resolve.

Schwebke et al. (1999) [4]
Premenopausal Transient fluctuations in VMF were common and often marked, however, the incidence of symptomatic BV in this cohort approached 10%.
Behaviors that were associated with unstable VMF are very similar to those that are associated with BV and STDs.
There was no correlation between use of hormonal contraception and changing flora.
An association between receptive oral sex and unstable VF was found. Strong similarities exist between the anaerobic bacteria associated with gingivitis and those associated with BV.
Use of vaginal medication and the occurrence of menses were the only 2 diary variables associated with adverse changes in VMF the day after the behavior.
Women who reported in their enrollment interview a greater number of sex partners in the past 12 months, more frequent episodes of vaginal intercourse, less frequent use of condoms, and use of spermicide were more likely to exhibit day-to-day changes in their VMF The number of subjects with high concentrations of Lactobacillus increased significantly over the menstrual cycle independent of the presence of BV, in contrast, the concentration of non-Lactobacillus species tended to be higher at menses.

Authors
A statistically significant linear decrease occurred in the recovery of Prevotella species from subjects without BV over the menstrual cycle.
Most VMF microorganisms were maintained at a rather stable rate over these 3 points of the menstrual cycle.
C. albicans was associated with both vulvar erythema and pruritus on days 19-24 of the menstrual cycle.
The volume of vaginal discharge increased and the amount of cervical mucus decreased over the menstrual cycle.

Vaginal self swabs 30
Gram stain Nugent et al. (1991) [9] Four cycles Alternate days Similar transient fluctuations over the menstrual cycle were found to those in industrialised countries.
There was no evidence that sexual intercourse was associated with increased frequency of BV.
The data did not support the hypotheses that menstrual hygiene materials might explain the high prevalences of BV found in sub-Saharan Africa compared to industrialised countries.
We found a high degree of fluctuation in women's patterns of vaginal flora over time.
We also did not find any association between frequency of intercourse and BV in the following menstrual cycle. Women with recurrent BV initially respond to antibiotic treatment with steep declines in bacterial concentrations, but these bacteria later reemerge, suggesting that antibiotic resistance in these bacteria is not an important factor mediating BV recurrence.

Authors
Recurrence of BV is associated with reappearance of BV-associated bacteria suggesting re-infection or resurgence from an endogenous reservoir.
The rate of decrease of the BV bacteria with antibiotic treatment varies, suggesting that longer antibiotic treatments may be warranted in some women.