As estrogen level decreases with aging, the vaginal mucosa gets thinner, and collagen amount decreases. In addition, the population of Lactobacillus in the vagina declines, increasing the risk of atrophic vaginitis, bacterial vaginosis, and genitourinary symptoms in the postmenopausal women. In this study, we evaluated the effects of Lactobacillus-containing feminine hygiene products on vaginal microbiome and genitourinary symptoms in pre- and postmenopausal women. This was a pilot randomized controlled trial in 35 premenopausal and 35 postmenopausal healthy women. For 4 weeks, treatment 1 group (14 premenopausal and 16 postmenopausal women) used the Lactobacillus-containing feminine soap and cream, and treatment 2 group (15 premenopausal and 14 postmenopausal women) used Lactobacillus-containing feminine gel in addition to soap and cream. The remaining 6 premenopausal and 5 postmenopausal women served as controls without using any products. We then compared the changes in the vaginal microbiota, genitourinary symptoms, and other related biomarkers after completion of treatment. Vaginal pH and pathogenic flora were reduced in both treatment groups compared to control group, which was more significant in the treatment 2 group of postmenopausal women. Genitourinary symptoms significantly improved in 60% of premenopausal women in treatment 1 group and 81.3% of postmenopausal women in treatment 2 group, compared to control group (0%, p = 0.043 and p<0.01 respectively). Overactive bladder symptom scores were significantly improved after using the products in eleven out of twelve postmenopausal women suspected of having overactive bladder. The use of Lactobacillus-containing feminine products was associated with improved vaginal ecosystem and urogenital health compared to control group, especially in those women using feminine gel.
Lactobacillus species, belonging to the group of lactic acid bacteria (LAB), are widely found in fermented food as well as in humans and animals. They produce lactic acids, thus lower pH and inhibit the growth of bacteria. Therefore, Lactobacillus species, through their natural protective actions, maintain the ideal vaginal environment and vaginal health [[
The prevalence of CSTs varies across different ethnic groups or geographical locations [[
GSM results from anatomical, histological and functional changes of the female genitourinary system due to reduced estrogen levels and ageing. GSM includes genital symptoms (dryness, burning, itching, irritation, bleeding), sexual symptoms (dyspareunia and other sexual dysfunctions) and urinary symptoms (dysuria, frequency, urgency, recurrent urinary infections) [[
Moderate to severe genitourinary symptoms might need hormonal therapies such as local estrogen treatment. However, probiotics therapies have emerged in recent days as an alternative method to protect urogenital health by improving the microbiological ecology in the genitourinary tract. Lactobacillus are empirically selected for such use. One pilot study showed that topical application of a Lactobacillus-ointment can increase the colonization of Lactobacillus in the external and internal genital areas of postmenopausal women up to 10 days after cessation of treatment [[
Based on the above evidences, makers produced and commercialized probiotics-based feminine care products in the market increasingly. However, few studies have assessed the influence of these products on vaginal microbiome, along with efficacy on genitourinary symptoms, before and after menopause. In the current study, we aimed to examine the changes in vaginal microbiome and genitourinary symptoms at baseline and four weeks after using the Lactobacillus plantarum and Lactobacillus rhamnosus containing feminine hygiene products in the pre and postmenopausal women. We hypothesized that using these products would change vaginal microbiota composition and diversity, and ultimately improve genitourinary symptoms. We also speculated that the effects would be different between pre and postmenopausal women.
This is a pilot randomized controlled trial comprising 70 healthy Japanese women, who volunteered to participate in the study conducted at the Hamasite Clinic in Tokyo Prefecture from April to July 2021. The recruitment process started in March 2021, using pamphlets and posters targeting the female employees at the Resorttrust, Inc., their relatives and friends. The contents include the importance of feminine care, the objectives of the study, inclusion and exclusion criteria, measurements, tests and products to be used, study period, incentive for participation, and contact details. Within one month of recruitment, seventy-three women registered for participation in the study. Among them, 70 were selected based on the inclusion and exclusion criteria as shown in Table 1 by the end of March, 2021. Half of them were premenopausal women, and half were postmenopausal women. Menopause was defined as no menstruation at least 12 months since the last menstrual period, follicular stimulating hormone level of 25mIU/mL and above and estradiol level less than 20 pg/ml.
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Table 1 Inclusion and exclusion criteria of the participants.
Inclusion criteria Exclusion criteria • Pre-menopausal women between 20–49 years of age • Postmenopausal women between 50–75 years of age • Who give consent on the research 1. Those under treatment for urinary tract infection 2. Those under treatment for urinary stone, hydronephrosis, renal tumor, etc. 3. Those who have taken antibiotics or steroids 2 weeks before the study or during the study 4. Those who have skin lesions on skin and mucosa of external genitalia or gynecological diseases such as vaginitis (except from asymptomatic atrophic vaginitis) 5. Those considered ineligible by the investigators
The Institutional Review Board of Medical Corporation Shinkokai approved the entire research protocol. We explained the details of the study to these women, and obtained their written informed consent. This study was registered with the University Hospital Medical Information Network (UMIN) Clinical Trial Registry (trial registration number: UMIN000043944). The full trial protocol can be accessed in the supplementary information.
We listed the premenopausal and postmenopausal women in the chronological order of their registration, and assigned each group into three groups (control, treatment 1 and treatment2) by simple randomization. Although the randomization ratio in the protocol was 1:3:3 (5 women in control:15 each in treatment 1 and 2), it became 1:2.3:2.5 in premenopausal women (6:14:15) and 1:2.8:3 in postmenopausal women (5:16:14) as the participants wished to change group before starting the intervention. Control group (6 premenopausal women and 5 postmenopausal women) used no feminine care products. Treatment 1 group (14 premenopausal women and 16 postmenopausal women) used the Lactobacillus-containing feminine foaming wash and cream. Treatment 2 group (15 premenopausal women and 14 postmenopausal women) received Lactobacillus-containing feminine gel in addition to treatment 1. The participants underwent baseline assessments at the Hamasite Clinic, Minato-ku, Tokyo Prefecture, during April and May, 2021. One premenopausal from treatment 1 group dropped out as vaginal assessments were not possible due to menstruation. Therefore, she was substituted with a new participant. Treatment 1 and 2 groups started using the feminine care products on the day after completion of baseline assessments. Treatment 1 group used two pumps of foaming wash (Product name: Delicate Softwash®), rubbed from front to back, and then washed out with water while taking bath every day. After patting the area dry, they gently applied feminine cream (Product name: Delicate Softgelcream®) for a few seconds around the labia majora covering about 2 cm in diameter after bath once a day. Treatment 2 group used vaginal gel (Product name: Inner gel®) with an applicator once in every three days before bedtime in addition to foaming wash and cream once a day. These feminine products contained Lactobacillus rhamnosus vitaP1 and Lactobacillus plantarum KCTC3108. All the products were produced by Hanamisui Co., Ltd. and distributed by Advanced Medical Care, Co. Ltd., both of which are based in Tokyo, Japan. The intervention groups reported no adverse or allergic reactions while using or after using these products for four weeks. They had follow-up assessments after 4-week trial period. Fig 1 showed the CONSORT flow diagram for this pilot randomized controlled trial. The doctors and nurses at Hamasite Medical Clinic generated the random allocation sequence, enrolled participants, and assigned participants to interventions. They also explained, distributed and monitored the use of feminine care products in the intervention groups.
Graph: Fig 1 CONSORT flow diagram.
Female sex hormones such as estradiol and follicular stimulating hormone levels were measured from the blood specimens of all participants, using Chemiluminescence Immunoassays (CLIA) Test. As there can be physiological fluctuations in women of reproductive age, we collected blood during the ovulatory phase, within a week after menstruation, in premenopausal women. However, in postmenopausal women who had no such fluctuations, we collected blood on the same day with other blood tests, pH test and microbial analysis. Gynecologists, who are involved as coinvestigators of this study, took the required samples and pH measurements from the vagina. Vaginal pH was determined by using pH test strips (pH‑Fix 3.6–6.1, Macherey-Nagel, Düren, Germany). The measurement of urinary equol was conducted as described by Yoshikata et al [[
The experienced gynecologists took vaginal swabs around the vaginal wall for microbial analysis. The collected vaginal specimens were put into the container with lysis buffer (4M Guanidine thiocyanate, 40 mM EDTA, 100 mM Tris-HCl pH 9.0) and stored at room temperature. After being transported to the laboratory, they were kept refrigerated and processed within two weeks from the date of collection. The bacterial cell walls were disrupted by a bead beater using zirconia beads to extract or isolate bacterial DNA. The extracted DNA was then purified using an automatic extraction device (Maxwell, Promega). After that approximately 300 base pairs in the V1 and V2 regions of the 16S rRNA fragments were amplified with the V1-V2 region specific primer set 27F/338 R using a thermal cycler (Veriti, Thermo Fisher Scientific, MA, USA). We used a mixture of modified 27F primer to optimize the amplification. The amplified products were then purified and quantified using a real-time PCR device (StepOne
All the 70 participants completed self-administered questionnaires regarding their genitourinary symptoms, menopausal symptoms, and overactive bladder symptoms before and after 4 weeks of intervention. Menopausal symptoms were assessed using the simplified menopausal index scale developed by Koyama in 1996 [[
We estimated the sample size for this study from an 8-week preliminary study on 12 premenopausal and 9 postmenopausal women before and after using feminine care products. We first calculated the effected size for the changes in vaginal microbial diversity as the primary outcome measure. We used that effect size (f = 0.53), with the assumption of a two-sided 5% significance level and power of 80%, and calculated that a minimum of 52 women in total was necessary for the comparison (baseline versus week 12) of six groups using a two-way repeated-measures ANOVA (analysis of variance) test. Considering 25% dropout, we recruited 70 people. The sample size calculations, data analysis and figure generation were performed using R software (R 4.1.0, R Core Team, 2021) and Microsoft Excel (Microsoft Corporation, 2018). The distribution of normality was assessed with the Kolmogorov–Smirnov test, box plots, and histograms. Categorical variables were expressed as numbers (N) and percentages (%), continuous variables were expressed as means with standard deviations, and scores were expressed as medians with interquartile ranges. Comparisons between groups were performed using the chi-squared test and Fisher's exact test for proportions, student's t-test for continuous variables, and Mann-Whitney U test for scores. The changes in pre- versus post-intervention values in each group were compared using paired t-test for continuous variables, and Wilcoxon Rank sum test for scores. Differences among control and treatment groups were compared using one-way ANOVA test for continuous variables and Kruskal-Wallis test for scores. All tests were two-sided, and statistical significance was set to p < 0.05.
Table 2 showed the basic characteristics of the participants in our study cohort. Postmenopausal women had higher urinary concentration of equol but lower proportion of equol producers although these findings were not statistically significant. Nevertheless, age-related changes, such as sex hormone levels and vaginal pH (4.37 ± 0.58 versus 5.89 ± 0.45, p<0.0001), were significantly different between the premenopausal and postmenopausal women. We also found significant differences in the Lactobacillus composition (72% ± 36.84 versus 10% ± 25.11, p<0.0001) as well as vaginal microbial diversity (0.77 ± 0.73 versus 1.92 ± 1.02, p<0.0001) between the two groups of women. Both the control and treatment groups had similar results in these parameters. Baseline simplified menopausal index scores showed no significant differences in any group of women. About 60% of the premenopausal and 50% of postmenopausal women scored less than 25. Another 30% of premenopausal women and 40% of postmenopausal women scored between 26 and 50. Therefore, almost all the women in each group had mild menopausal symptoms without requiring special treatment. Baseline overactive bladder symptom scores (OABSS) were similar between the intervention and control groups. However, postmenopausal women had significantly higher scores compared to the premenopausal women (0.86 versus 2.97, p <.0001). More than 90% of premenopausal women scores less than 3, which is considered having no overactive bladder. However, about 34% of postmenopausal women scored 3 and above, suspected as having overactive bladder (p<0.001).
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Table 2 Summary of characteristics of the participants in the study cohort.
Premenopausal women (n = 35) Postmenopausal women (n = 35) All Control (n = 6) Treatment 1 (n = 14) Treatment 2 (n = 15) p-valuea All Control (n = 5) Treatment 1 (n = 16) Treatment 2 (n = 14) p-valuea p-valueb Age, years 37.26 ± 6.09 36.17 ± 6.18 37.64 ± 5.97 37.33 ± 6.54 0.888 59.86 ± 4.81 60.80 ± 3.70 59.88 ± 6.17 59.50 ± 3.44 0.880 <.00001 Height, centimeter 158.97 ± 4.47 161.67 ± 3.83 158.71 ± 4.91 158.13 ± 4.12 0.259 156.74 ± 4.98 157.20 ± 5.45 156.75 ± 4.60 156.57 ± 5.58 0.973 0.074 Weight, kilograms 53.66 ± 9.26 53.33 ± 2.88 55.14 ± 10.08 52.40 ± 10.35 0.737 55.12 ± 8.01 57.60 ± 6.19 54.75 ± 5.56 54.62 ± 11.05 0.765 0.51 FSH 6.62 ± 9.41 5.55 ± 1.03 6.15 ± 8.37 7.49 ± 12.17 0.892 58.89 ± 20.66 61.70 ± 22.52 53.78 ± 17.24 63.71 ± 23.61 0.412 <.00001 E2 168.10 ± 261.06 96.52 ± 36.23 272.99 ± 389.72 98.84 ± 75.33 0.153 10.00 ± 0.00 10.00 ± 0.00 10.00 ± 0.00 10.00 ± 0.00 <.00001 Urinary equol concentration, μM 4.47 ± 8.71 3.83 ± 4.86 2.25 ± 2.37 6.80 ± 12.64 0.377 8.63 ± 15.92 1.53 ± 2.67 8.34 ± 11.84 11.49 ± 21.70 0.498 0.18 Equol producer status (n, %) 0.351 0.3291 0.809 Equol non-producer 19 , 54% 2 , 33% 7 , 50% 10 , 67% 21 , 60% 4 , 80% 7 , 47% 10 , 67% Equol producer 16 , 46% 4 , 67% 7 , 50% 5 , 33% 14 , 40% 1 , 20% 8 , 53% 5 , 33% Vaginal pH 4.35 ± 0.59 4.12 ± 0.29 4.56 ± 0.80 4.23 ± 0.36 0.189 5.90 ± 0.45 5.94 ± 0.36 5.98 ± 0.36 5.79 ± 0.56 0.519 <.00001 SMI scores 20.0 (12.5–40) 10.0 (5.75–6.3) 19.5 (12.25–41.8) 23.0 (15–38.5) 0.382 26.0 (11.5–0.5) 10.0 (5–51) 25.5 (6.5–32.8) 28.0 (16.25–42) 0.471 0.8785 SMI category 0.413 0.058 0.703 0–25 20 , 57% 4 , 67% 8 , 57% 8 , 53% 17 , 49% 3 , 60% 8 , 50% 6 , 43% 26–50 11 , 31% 1 , 17% 6 , 43% 4 , 27% 13 , 37% 0 , 0% 8 , 50% 5 , 36% 51–65 4 , 11% 1 , 17% 0 , 0% 3 , 20% 4 , 11% 1 , 20% 0 , 0% 3 , 21% 66–80 0 , 0% 0 , 0% 0 , 0% 0 , 0% 0 , 0% 0 , 0% 0 , 0% 0 , 0% 81–100 0 , 0% 0 , 0% 0 , 0% 0 , 0% 1 , 3% 1 , 20% 0 , 0% 0 , 0% OABS scores 0.0 (0–1.5) 0.0 (0–0.8) 1.0 (0–1) 0.0 (0–2) 0.492 2.0 (1–4) 2.0 (1–4) 1.5 (1–3.3) 2.0 (1–4) 0.864 <.0001 OAB category 0.802 0.248 <.0001 Overall scores <3 33 , 94% 6 , 100% 13 , 93% 14 , 93% 21 , 60% 3 , 60% 10 , 63% 8 , 57% OAB suspect 2 , 6% 0 , 0% 1 , 7% 1 , 7% 12 , 34% 1 , 20% 5 , 31% 6 , 43% OAB Mild 0 , 0% 0 , 0% 0 , 0% 0 , 0% 1 , 3% 0 , 0% 1 , 6% 0 , 0% OAB Moderate 0 , 0% 0 , 0% 0 , 0% 0 , 0% 1 , 3% 1 , 20% 0 , 0% 0 , 0%
1 FSH: Follicular Stimulating Hormone, E2: Estradiol, SMI: Simplified Menopausal Index, OABS: Overactive Bladder Symptoms, OAB: Overactive Bladder.
- 2 OAB suspect as defined as having an overall scores 3 and above. OAB was defined as having urinary urgency once a week or more (Q2: Score 2 and above) and overall OABS score of 3 and above. Mild OAB was defined as having an overall OABS score at least 5 and Moderate OAB was defined as having an overall OABS score between 6 to 11.
- 3 p-value
a : Chi-squared test and Fisher's exact test for proportions, ANOVA for continuous variables, and Kruskal-Wallis test for scores for comparisons among control and treatment groups. - 4 p-value
b : Chi-squared test for proportions, t-test for continuous variables, and Mann-Whitney U test for scores for comparisons between premenopausal and postmenopausal women.
Fig 2 showed genitourinary symptoms reported in each group of women and their effects on their daily lives. Almost 60% of women in each group (20 premenopausal women and 22 postmenopausal women) reported that they had at least one genitourinary symptom. In premenopausal women, the most common symptoms were bad odor, itchiness, and increased discharge. Postmenopausal women reported more urinary symptoms such as urinary incontinence, frequency, and dyspareunia. While 70% or 14 out of 20 symptomatic premenopausal women rated these effects as mild, 32% (n = 7) rated them as moderate, and 18% (n = 4) rated these effects as severe among 22 symptomatic postmenopausal women. Therefore, postmenopausal women had stronger genitourinary symptoms. We also found significant differences in the Lactobacillus composition (72% ± 36.84 versus 10% ± 25.11, p<0.0001) as well as vaginal microbial diversity (0.77 ± 0.73 versus 1.92 ± 1.02, p<0.0001) between the two groups of women (Table 3). Both the control and treatment groups had similar results in these parameters.
Graph: Fig 2 Self-reported genitourinary symptoms and their effects on daily activities.Genitourinary symptoms were more varied and stronger in postmenopausal women. Changes after four weeks.
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Table 3 Baseline vaginal microbiome compositions of the participants in the study cohort.
Premenopausal women (n = 35) Postmenopausal women (n = 35) All Control (6) Treatment 1 (14) Treatment 2 (15) p-valuea All Control (5) Treatment 1 (16) Treatment 2 (14) p-valuea p-valueb Microbial diversity 0.77 ± 0.72 0.69 ± 0.89 0.81 ± 0.82 0.76 ± 0.57 0.949 1.92 ± 1.01 2.11 ± 1.15 2.03 ± 1.10 1.72 ± 0.88 0.647 <.00001 Total 71.98 ± 36.84 87.77 ± 19.30 64.23 ± 43.89 72.90 ± 34.73 0.433 10.08 ± 25.11 6.67 ± 10.07 7.36 ± 22.81 14.41 ± 31.37 0.718 <.00001 31.71 ± 43.24 35.98 ± 48.31 29.25 ± 41.94 32.29 ± 45.38 0.595 1.10 ± 6.39 7.57 ± 16.92 0.04 ± 0.16 0.01 ± 0.03 0.118 0.001 5.02 ± 14.37 5.41 ± 13.25 1.02 ± 3.83 8.60 ± 19.88 0.551 1.59 ± 7.66 0.00 ± 0.00 3.48 ± 11.22 0.00 ± 0.00 0.033 34.54 ± 41.70 46.30 ± 51.08 39.80 ± 43.80 24.93 ± 36.37 0.201 4.80 ± 19.43 0.36 ± 0.50 0.07 ± 0.24 11.80 ± 29.98 0.296 <.001 0.00 ± 1.57 0.00 ± 0.82 0.00 ± 1.22 0.00 ± 1.92 0.00 ± 0.02 0.00 ± 0.00 0.00 ± 0.00 0.01 ± 0.03 Pathogenic bacteria (CST IV) 14.89 ± 26.27 4.48 ± 10.94 19.55 ± 32.21 14.71 ± 24.54 0.515 0.77 ± 4.07 0.00 ± 0.00 0.18 ± 0.71 1.73 ± 6.41 0.518 0.34 Others 8.36 ± 17.37 7.31 ± 16.92 5.66 ± 10.24 11.29 ± 22.71 0.688 63.14 ± 34.39 55.38 ± 40.70 69.98 ± 30.37 58.10 ± 37.57 0.566 <.00001
- 5 p-value
a : ANOVA for continuous variables for comparisons among control and treatment groups. - 6 p-value
b : t-test for comparisons between premenopausal and postmenopausal women.
Fig 3A and 3B showed the landscape of distribution of pathogenic flora, Lactobacillus species and other bacterial communities in premenopausal and postmenopausal women. In premenopausal women, Lactobacillus population increased. In general, pathogenic flora population decreased in both groups. Fig 4 showed that vaginal pH and pathogenic flora proportions significantly reduced in postmenopausal women in treatment 2 intervention group (5.79 versus 5.65, p<0.05 and 27.491 versus 4.083, p<0.05, respectively). However, microbial diversity showed a significant increase in treatment 1 group of postmenopausal women (2.03 versus 2.73, p<0.05). One-way ANOVA test showed that pH reduction in treatment 2 postmenopausal group was significant when compared to the postmenopausal control group (p = 0.027). Apart from that, no significant differences were observed in vaginal pH, microbial diversity, and proportions of vaginal pathogenic flora in comparison with the control groups.
Graph: Fig 3 Distribution of pathologic flora and Lactobacillus species in the vagina at baseline and four weeks after intervention.In premenopausal women, Lactobacillus population appeared to be increased, and pathogenic flora decreased in postmenopausal women. In general, pathogenic flora population decreased in both groups.
Graph: Fig 4 Changes in vaginal pH, microbial diversity and the proportions of vaginal pathogenic flora at baseline and four weeks after intervention.Pathogenic flora population was significantly decreased in the postmenopausal group using three feminine hygiene products.
Fig 5A showed that no one in the control group reported improvement in genitourinary symptoms, but these symptoms significantly improved in treatment 2 group of premenopausal women (0% versus 60%, p = 0.043) and treatment 1 group of postmenopausal women (0% versus 81.3%, p<0.01) compared to the control group. Among 37 symptomatic women, 27 (73%) reported that their symptoms got improved after undergoing either treatment 1 or treatment 2. Even among 22 asymptomatic women, 32% (n = 6) reported better wellbeing. In premenopausal women, the most improved symptom reported among treatment 1 group was odor and that was discharge among treatment 2 group. In post-menopausal women, both groups reported improvement in a wide variety of symptoms.
Graph: Fig 5 Changes in genitourinary symptoms after 4 weeks.Genitourinary symptoms significantly improved in treatment 2 group of premenopausal women and treatment 1 group of postmenopausal women compared to the control group.
As shown in Fig 6, the median simplified menopausal index scores showed only marginal changes except in premenopausal treatment 2 group where menopausal symptom scores improved after 4 weeks (23 versus 15, p<0.005). The overactive bladder symptom scores did not change much before and after 4-week treatment in all groups. Among 12 postmenopausal women in the intervention groups who had baseline OABS scores of 3 and above (overactive bladder suspect), 11 women had significantly reduced OABS scores after using feminine hygiene products (p<0.0001).
Graph: Fig 6 Changes in median symptom scores after 4-week treatment with feminine care products.Simplified menopausal index scores in premenopausal treatment 2 group reduced after 4 weeks. Significantly improved OABB symptom scores were seen in those with OABB symptom scores more than 3 in postmenopausal women after 4 weeks of treatment.
Genitourinary symptoms of menopause (GSM) are the new terms for a broad spectrum of symptoms comprising of urinary symptoms and sexual symptoms in addition to the existing vulvovaginal atrophy (VVA) symptoms. It was first introduced in 2014 by a consensus of the International Society for the Study of Women's Sexual Health and the North American Menopause Society. More than half of the women in the middle age were reported of having GSM.
In this study, approximately 60% of healthy women in each premenopausal and postmenopausal group experienced at least one genitourinary symptom. Postmenopausal women had worse symptoms and 50% of them reported that these symptoms affected their daily lives significantly. After using feminine hygiene products, genitourinary symptoms got significantly improved in the treatment 2 group of premenopausal women and treatment 1 of postmenopausal women. At baseline, postmenopausal women had more urinary symptoms such as urinary incontinence, frequencies, etc. However, those symptoms significantly improved in postmenopausal women with OABB scores more than 3 after using feminine hygiene products. Since genitourinary symptoms were significantly associated with overactive bladder symptoms [[
Lactobacillus iners (CST III) was the most prevalent community subtype of Lactobacillus in the women in our study. This was consistent with the CST prevalence studies in the previous studies on Asian women [[
As with the majority of studies, our study has a few limitations. An important limitation of this study was insufficient sample size especially in the premenopausal women, leading to low power. A post hoc power analysis was conducted using R statistical software 4.1. The analysis revealed that, for an effect size of 0.617 in vaginal pH, and 0.733 in the proportions of pathogenic flora in the premenopausal women, the statistical power of the one-way ANOVA was 45.5% and 60.2% respectively for at least 5 participants in the control group, which was significant at the 5% level (two tailed). We need at least 10 participants per group to yield a statistical power of 80% or more in the premenopausal women. We might have overestimated the effect size in our small preliminary study without a control group. Not only the sample size, but also the length of the study can limit the benefits of the treatments as the pilot study lasted longer than this study (8 weeks versus 4 weeks). With few observations and longer duration, the results of the preliminary study would possess less precision and accuracy and more effect size. Moreover, due to the nature of microbial heterogeneity among the participants, we need larger and longer trials to evaluate the effectiveness of feminine care products. We also need to assess whether intermittent or continued use of feminine hygiene products is effective since the recurrence of bacterial vaginosis is common after several months. In addition, we need to identify the probiotic strains and administrative routes that could yield the best possible outcome. Moreover, unequal allocations of participants in the groups had consequences for statistical power as we had allowed the participants to change group before starting the intervention. But some reported that such unequal allocations might have some advantages in pilot trials, for exploring treatment dimensions in clinical utility [[
Genitourinary symptoms might be improved using feminine hygiene products containing Lactobacillus in a wide range of women populations. Such products can also create a better balance of Lactobacillus and pathogenic flora population, especially in the postmenopausal women. Direct application of Lactobacillus inside the vagina might produce better results. However, we need larger comparative studies with different intervention periods, probiotic strains and administrative routes to evaluate the best possible outcome of using Lactobacillus in the maintenance of healthy vaginal ecosystem.
S1 File. Simplified menopausal index questionnaire.
(PDF)
S2 File. Overactive Bladder Symptom Scores (OABSS).
(PDF)
S3 File. Proposal in Japanese.
(PDF)
S4 File. Proposal in English translation.
(PDF)
S5 File. Consort checklist.
(PDF)
S6 File. Figures.
(ZIP)
S1 Data.
(XLSX)
We would like to acknowledge all the women who willingly participated in the study.
By Remi Yoshikata; Michiko Yamaguchi; Yuri Mase; Ayano Tatsuyuki; Khin Zay Yar Myint and Hiroaki Ohta
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