Probiotics for the Treatment of Bacterial Vaginosis
By Donald Brown, ND, Naturopathic Physician and Director of Natural Product Research Consultants, Seattle, WA. Dr. Brown is a consultant to the supplement industry. He reports no relevant financial relationships to any of the probiotic strains discussed in this article.
Bacterial vaginosis (BV) is a common vaginal infection causing significant gynecologic and obstetric morbidity. Though no single pathogen has been identified as the causative agent of BV, Gardnerella vaginalis and Atopobium vaginae are commonly associated with the condition.1 Typical symptoms are said to include vaginal malodor, itching, dysuria, and thin discharge, but a substantial number of women with BV are asymptomatic.2 BV has been associated with pelvic inflammatory disease, infections following gynecologic surgery, and preterm birth.3 Estimates suggest that 40% of cases of spontaneous preterm labor and preterm birth may be associated with BV.4 Some evidence also suggests the presence of BV may increase risk of HIV-infection.5
Treatment for the condition consists of metronidazole or clindamycin, administered orally or intravaginally. However, these antimicrobials are sometimes ineffective and many women have high recurrence rates following treatment (30% at 3 months and up to 50% at 6 months).6 A study of women with BV found that an adherent biofilm of primarily G. vaginalis and A. vaginae persisted 3 weeks after treatment with metronidazole.7
Vaginal Microbiota and BV
The estimated number of microbial species inhabiting the vagina is 50, compared to approximately 800 species in the intestinal tract.8 The vaginal microflora of healthy premenopausal women is generally dominated by Lactobacillus species, especially Lactobacillus crispatus, L. gasseri, L. jensenii, and L. iners.9,10 Factors influencing the vaginal microflora include hormonal changes (especially estrogen), vaginal pH and glycogen, and the use of topical microbicides.8 Lactobacilli in the vagina have been associated with the following protective roles against uropathogens (including those associated with BV): 1) inhibition of binding of pathogenic bacteria; 2) production of H2O2 and lactic acid that may limit pathogen growth; and 3) regulation of epithelial innate immunity.11-14 A recent in vitro study found that L. rhamnosus RC-14 and L. reuteri RC-14 (see clinical research review below) are able to incorporate themselves into the biofilms created by G. vaginalis and A. vaginae and cause disruption of the biofilm and even some killing of the bacteria.15
The presence of H2O2-producing Lactobacilli spp. has been shown to be significantly higher in healthy women compared to those with BV.16 In one study, vaginal lactobacilli were isolated from 73.7% of 825 women without BV compared to 29.8% of 131 women with BV (P < 0.001).17 In a study of pregnant women, lactobacilli were isolated from 74.3% of women without BV compared to 38.4% of women with BV (odds ratio 0.7, 95% confidence interval 0.6-0.8).18 In a study with Chinese women (aged 23-45 years), healthy subjects had a higher vaginal count of L. crispatus and a lower count of L. iners compared to women with BV.19 A study with pregnant Japanese women found that the presence of L. cripsatus, L. gasseri, and L. jensenii was higher in healthy women compared to those with BV.20 The study also found that presence of L. iners was associated with a greater risk of colonization by BV-related bacteria.
Probiotics for the Treatment of BV
Several clinical trials to date have been completed to study the effects of specific strains of lactobacilli to colonize the vaginas of women with symptomatic or asymptomatic BV, to reduce colonization of pathogens, and to improve symptoms and/or signs of BV when they are present. Although this review will focus primarily on more recent studies using probiotics as adjunctive therapy with standard antimicrobial therapy, readers also may want to review the excellent meta-analysis published in 2007 by Falagas et al that reviews the data from 10 studies published between 1992 and 2005.3
It is interesting to note that the more contemporary research using probiotics for the treatment of BV continues to be divided between intravaginal or oral application. The assumption for many years (and that continues in some circles) is that intravaginal application was the only means to efficiently deliver probiotics for the treatment and/or prevention of female genitourinary tract infections such as BV. Canadian researchers led by Gregor Reid have challenged this assumption with the development of two lactobacilli strains that were isolated from the vaginas of healthy women L. rhamnosus RC-14 and L. reuteri RC-14 (previously identified as L. fermentum RC-14). Reid and colleagues found that oral administration of the two strains to 64 healthy women (ages 19-46 years) for 60 days resulted in a significant increase in vaginal lactobacilli at day 60 compared to a group taking placebo (P = 0.05), as well as a reduction in yeast and coliforms in the probiotic group.21 Although all women in the study reported being asymptomatic at the time of recruitment, 16 of 64 (25%) had asymptomatic BV at day 0. Of those subjects who did not have BV at baseline, 6 of 25 (24%) receiving placebo developed BV at day 35 and 6 at day 56 compared to none of the probiotic group (P < 0.05). A follow-up study found that oral delivery of the same strains was not only effective in colonizing the intestinal tract (based on fecal analysis) of healthy women but also the vagina.22
Vaginal Application of Probiotics
In a single-center, randomized, observer-blinded study, 190 women (ages 18-45 years) diagnosed with BV were treated with clindamycin (300 mg bid) for 7 days and then randomized to receive a vaginal capsule containing L. casei rhamnosus (Lcr35 [Gynophilus; Laboratories Lyocentre, France], 1 x 109 colony forming units [cfu]) or no further treatment the next 7 days.23 Final vaginal swabs for Nugent scoring were taken 4 weeks after the last administration of clindamycin (the scoring system examines vaginal cells at random and applies a 0-3 score for normal [dominated by gram-positive bacilli resembling lactobacilli], 4-6 for intermediate [lactobacill present along with gram-negative or gram-variable rods], and 7-10 for BV [no lactobacilli seen and cells conlonized by gram-negative rods]). The primary outcome was the change in the Nugent score between baseline and at the end of the study of at least 5 grades.
At the end of the study, 83% of the women in probiotic group compared to 35% in the control group showed a reduction of the Nugent score by at least 5 grades (P < 0.001). A reduction of 8 grades on the Nugent score was found in 60% of women in the probiotic group compared to 14% in the placebo group. The median difference between initial and final swabs was 6.61 in the probiotic group and 4.13 in the control group (P < 0.001). There is no indication that adverse events were tracked during the study. The results suggest that intravaginal application of Lcr35 following antibitoic therapy is able to effectively restore the vaginal flora to a healthier level based on the Nugent score.
In a randomized, double-blind, placebo-controlled trial (RDBPCT), 100 women (mean age 34 years) with BV were treated with 2% clindamycin cream for 7 days and then randomized to receive vaginally inserted capsules containing either a placebo or a probiotic combination of L. gasseri (Lba EB01-DSM 14869) and L. rhamnosus (Lbp EB01-DSM 14870) containing 1 x 108-9 cfu of each organism per capsule.24 The two strains were cultured from healthy women in Norway. Following the 7-day course of clindamycin, patients were instructed to insert the vaginal capsules daily for 10 days or until menstruation started. After each menstruation, this 10-day application was repeated for 3 cycles. Women who were considered to still have BV after the first menstruation were retreated with clindamycin and excluded from the study. Treatment was considered a cure when the Hay/Ison score was 1; a score of 2 was designated as "improved," and a score of 3 was a treatment failure (the Hay/Ison criteria uses the following grades based on a gram-staind vaginal smear: Grade 1 [normal] lactobacilli morphotypes predominate; Grade 2 [intermediate] mixed flora with some lactobacilli present but Gardnerella and/or Mobiluncus morphotypes also present; and Grade 3 [BV] predominately Gardnerella and/or Mobiluncus morphotypes and few or absent lactobacilli). Treatment efficacy was based on both cure after one month and the length of time to relapse using the Kaplan-Meier survival analysis.
The initial intention to treat (ITT) cure rate after the first menstruation was 64% for the probiotic group and 74% for the placebo group. However, when considering missing or unclassified vaginal swabs or missed capsules, the rates were 77% and 78%, respectively. The 76 women initially classified as cured were followed until their sixth menstrual cycle or until relapse. There was a significant difference (P = 0.027) in favor of the probiotic-treated women in duration of time from cure to relapse. At the end of the study, 64.9% of the probiotic group compared to 46.2% of the placebo group were cured (P = 0.042). Adverse events were similar in both groups and there was one possible case of vaginal discomfort due to allergy in the probiotic group.
Oral Use of Probiotics
In a RDBPCT, the efficacy of an oral probiotic combination was studied in women being treated for BV with metronidazole.25 One hundred and twenty-five women (18-44 years old) initially were entered in the study. All subjects received oral metronidazole (550 mg bid) from days 1 to 7 and were randomized to receive one capsule containing L. rhamnosus GR-1 (1 x 109 cfu) and L. reuteri RC-14 (1 x 109 cfu) or placebo orally bid from days 1 to 30. Chris Hansen, Horsholm, Denmark, supplied the probiotic combination. The primary outcome was the cure of BV as determined by a normal Nugent score, absence of clue cells, negative sialidase test, and no signs or symptoms (no discharge or fishy odor) of BV at day 30.
One hundred six women returned for the 30-day follow-up visit. In the probiotic group, 88% of women were cured compared to 40% in the antibiotic/placebo group (P < 0.001). Of the remaining probiotic subjects (12%), none had frank BV. All had mild irritative symptoms, no discharge or odor, a weakly positive sialidase score, and intermediate Nugent score. This contrasted with the remaining 34 placebo subjects, of which half had BV and the other half had an intermediate status. According to the study report, 100% of the probiotic-treated patients no longer were diagnosed with BV, while 30% of the placebo group was positive. High counts of Lactobacillus sp. (> 105 cfu/ml) were recovered from the vagina of 96% of the probiotic-treated subjects compared to 53% of controls at day 30. No significant adverse events were reported. The study reports a high dropout rate in the probiotic group (n = 16) compared to the placebo group (n =3). Although the investigators suggest this is due to the patients feeling better and assuming they were cured, an intention-to-treat analysis that included these subjects should have been included.
A second RDBPCT studied the same oral probiotic combination in 64 women (ages 16-51 years) diagnosed with BV.26 All patients were treated with a single dose of tinidazole (2 g) and then randomized to receive two capsules containing L. rhamnosus GR-1 and L. reuteri RC-14 (each capsule contained 1 x 109 cfu of each probiotic strain) or placebo orally in the morning for 28 days. Subjects, who reported suffering from recurrent BV, were distributed in a balanced fashion between the probiotic (n = 8) and placebo (n = 7) groups.
At day 28, significantly more women in the probiotic group than the placebo group had normal vaginal smears according to the Nugent score (P = 0.011) and Amsel criteria (P = 0.001; the Amsel criteria are used in clinical practice to diagnose BV and include: 1) thin, white, yellow, homogenous discharge; 2) clue cells on microscopy; 3) pH of vaginal fluid of > 4.5; and 4) release of a fishy odor on adding 10% potassium hydroxide). This translated to a cure rate of 87.5% for the probiotic group compared to 50% for the placebo group (P < 0.05). The vaginal smears of the placebo group showed a higher presence of gram-variable cocci-rods and curved gram-negative rods deemed indicative of BV compared to the probiotic group (P < 0.05). Considering only those patients with recurrent BV, 75% of those in the probiotic group were cured compared to 57.1% in the placebo group (P < 0.05). No significant adverse events were reported.
Conclusion
The role of "bacillus" in the health of the female genitourinary tract was first described in 1892 by Albert Döderlein. Long referred to as "Döderlein bacillus," we now know that the healthy vaginal flora is made up primarily of members of the Lactobacillus family. Various in vitro studies have demonstrated the ability of specific strains of lactobacilli to inhibit the growth of bacteria causing BV as well as inhibiting adherence and possibly interfering with the formation of biofilms.
Newer clinical studies suggest that the adjunctive use of probiotics with standard antimicrobial therapy may not only improve treatment outcomes but also prevent recurrence in women with BV. While promising, the data are split between different routes of probiotic administration as well as varied proprietary strains. With two studies confirming efficacy, the oral combination of L. rhamnosus GR-1 and L. reuteri RC-14 appears to be the frontrunner for future clinical studies (2 x 1010 cfu of each strain per day). Larger and longer trials with a focus on prevention are needed in a more diverse group of women to firmly establish probiotics as a viable clinical option for the treatment and prevention of BV. Considering the fact that women with BV have been treated with the same antimicrobial treatments for the past 40 years and the significant rate of recurrence paired with the health risks associated with BV, the further development of probiotics in the management and prevention of BV appears to be a sound investment.
Recommendation
Women being treated for BV with antimicrobial therapy should be educated about the potential benefits of adjunctive use of specific probiotic strains to potentially improve treatment outcomes, prevent recurrence, and re-establish healthy vaginal flora. Preliminary data suggests that longer-term ingestion may be more effective than short-term ingestion and may point to the need for women with a history of recurrence to consider ongoing use of probiotics.
References
1. Bradshaw CS, et al. The association of Atopobium vaginae and Gardnerella vaginalis with bacterial vaginosis and recurrence after oral metronidazole therapy. J Infect Dis 2006;194:828-836.
2. Klebanoff MA, et al. Vulvovaginal symptoms in women with bacterial vaginosis. Obstet Gynecol 2004;104:267-272.
3. Falagas ME, et al. Probiotics for the treatment of women with bacterial vaginosis. Clin Microbiol Infect 2007;13:657-664.
4. Pretorius C, et al. The relationship between periodontal disease, bacterial vaginosis, and preterm birth. J Perinat Med 2007;35:93-99.
5. Jamieson DJ, et al. Longitudinal analysis of bacterial vaginosis: Findings from the HIV epidemiology research study. Obstet Gynecol 2001;98:656-663.
6. Bradshaw CS, et al. High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence. J Infect Dis 2006;193:1478-1486.
7. Swindsinki A, et al. An adherent Gardnerella vaginalis bioflilm persists on the vaginal epithelium after standard therapy with oral metronidazole. Am J Obstet Gynecol 2008;198:97.e1-6.
8. Waigankar SS, Patel V. Role of probiotics in urogenital health. J Mid-Life Health 2011:2:5-10.
9. Antonio M, et al. The identification of vaginal Lactobacillus species and the demographic and microbiologic characteristics of women colonized by these species. J Infect Dis 1999;180:1950-1956.
10. Vasquez A, et al. Vaginal Lactobacillus flora of healthy Swedish women. J Clin Microbiol 2002;40:2746-2749.
11. Boris S, et al. Adherence of human vaginal lactobacilli to vaginal epithelial cells and interaction with uropathogens. Infect Immun 1998;66:1985-1989.
12. Mastromarino P, et al. Characterization and selction of vaginal Lactobacillus strains for the preparation of vaginal tablets. J Appl Microbiol 2002;93:884-893.
13. McLean NW, McGroarty JA. Growth inhibition of metronidazole-susceptible and metronidazole-resistant strains of Gardnerella vaginalis by lactobacilli in vitro. Apply Environ Microbiol 1996;62:1089-1092.
14. Fichorova RN, et al. Novel vaginal microflora colonization model providing new insight into microbicide mechanism of action. mBio 2011:2(6):e00168-11.
15. McMillan M, et al. Disruption of urogenital biofilms by lactobacilli. Colloids Surfaces B: Biointerfaces 2011;86:58-64.
16. Eschenbach DA, et al. Prevalence of hydrogen peroxide-producing Lactobacillus species in normal women and women with bacterial vaginosis. J Clin Microbiol 1989;27:251-256.
17. Helberg D, et al. The diagnosis of bacterial vaginosis and vaginal flora changes. Arch Gynecol Obstet 2001;265:11-15.
18. Thorsen P, et al. Few microorganisms associated with bacterial vaginosis may constitute the pathologic core: A population-based microbiologic study among 3596 pregnant women. Am J Obstet Gynecol 1998;178:580-587.
19. Yan DH, et al. Comparison of main Lactobacillus species between healthy women and women with bacterial vaginosis. Chin Med J 2009;122:2748-2751.
20. Tamrakar R, et al. Association between Lactobacillus species and bacterial vaginosis-related bacteria, and bacterial vaginosis scores in pregnant Japanese women. BMC Infect Dis 2007;7:128(doi:10.1186/1471-2334-7-128).
21. Reid G, et al. Oral use of Lactobacillus rhamnosus GR-1 and Lactobacillus fermentum RC-14 signficantly alters vaginal flora: Randomized, placebo-controlled trial in 64 healthy women. FEMS Immunol Med Microbiol 2003;35:131-134.
22. Morelli L, et al. Utilization of the intestinal tract as a delivery system for urogenital probitoics. J Clin Gastroenterol 2004;38(suppl2):S1-S4.
23. Petricevic L, Witt A. The role of Lactobacillus casei rhamnosus Lcr35 in restoring the normal vaginal flora after antibiotic treatment of bacterial vaginosis. BJOG 2008;115:1369-1374.
24. Larsson PG, et al. Human lactobacilli as supplementation of clindamycin to patients with bacterial vaginosis reduce the recurrence rate; a 6-month, double-blind, randomized, placebo-controlled study. BMC Women Health 2008;8:3(doi: 10.1186/1472-6874-8-3).
25. Anukam K, et al. Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: Randomized, double-blind, placebo controlled trial. Microbes Infection 2006;8:1450-1454.
26. Martinex RCR, et al. Improved cure of bacterial vaginosis with single dose of tinidazole (2 g), Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14: A randomized, double-blind, placebo-controlled trial. Can J Microbiol 2009;55:133-138.
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