Bacterial Vaginosis: An Underestimated Cause of Unexplained Infertility

Introduction

Bacterial Vaginosis (BV) is a common disorder of the genital tract in women characterized by an alteration of the normal acidic lactobacilli-predominant vaginal ecosystem with an increase in pH [1]. The infection is characterized primarily by paucity or depletion of the vaginal lacto-bacilli and their replacement by an outgrowth of different micro-organisms including Gardnerella vaginalis (GV), anaerobic rods, pepto- streptococci, and mycoplasma species [2]. Bacterial Vaginosis (BV) is the most common cause of abnormal vaginal discharge among women of child bearing age and is associated with adverse obstetric and gynecologic outcomes [3]. Common symptoms include increased vaginal discharge that often smells like fish, the discharge is usually white or gray in colour, burning with urination may occur, mild itching.

Vaginal Flora in reproductive Indian women

The microbial species that inhabit the vaginal tract play an important role in the maintenance of health, and prevention of infection. Despite the close proximity of the vagina to the anus, the diversity of microbes present in the vagina is much lower than in the gut. Lactobacilli are the most common, particularly in healthy women [4].

Using molecular-based techniques, it is known that healthy vaginal microflora does not contain high numbers of many different species of Lactobacillus. Rather, one or two lactobacilli from a range of three or four species (mainly L. crispatus and L. iners, but also Lactobacillus jensenii and Lactobacillus gasseri) are dominant, whereas other species are rare & lower in titer [5].

In a study conducted in 132 women of Mysore, the predominant Lactobacilli species isolated were L. gasseri (46%), L. crispatus (40%) and L. jensenii (14%) [6]. In another study steered by Kiss et al in 200 healthy pregnant women, the most frequently occurring species were Lactobacillus crispatus and Lactobacillus gasseri, followed by Lactobacillus jensenii and Lactobacillus rhamnosus [7].

Vaginal Lactobacillus Microbiota of Healthy Women in the Late First Trimester of Pregnancy

Majority of cases of BV are asymptomatic and remain unreported and untreated. The role of asymptomatic compared with symptomatic BV in both gynecologic and pregnancy-related conditions have been less studied [8].

Significance of Probiotics Treatment in BV

Studies have suggested that the presence of H2O2 (hydrogen peroxide) producing vaginal lactobacilli may protect against BV by inhibiting the adherence of Gardnerella vaginalis and produce hydrogen peroxide, lactic acid and bacteriocins, which inhibits the growth of bacteria causing BV [11].

A review by MacPhe, et al. recommends the inclusion of probiotics as part of the approach to disease prevention and as an adjunct to antimicrobial treatment [12]. Neither the immune system nor antibiotics eradicate all of the microbes; therefore biofilm related infections may be persistent and women with BV tend to have high recurrence rates.

Role of Lactobacilli Strain

L. gasseri and L. jensenii co aggregate with G. vaginalis (pathogenic bacteria) and block the adherence and ⁄ or displace previously adherent strains of G. vaginalis from vaginal epithelial cells. L. gasseri, L crispatus produce large amounts of H2O2 and inhibits the growth of G. vaginalis while L. rhamnosus increases colonization of lactobacilli and decreases the recurrence of BV [11].

Macklaim, et al. (2015) reported that treatment of BV with antimicrobial therapy and probiotic supplementation, namely Lactobacillus reuteri and Lactobacillus rhamnosus, increased the abundance of indigenous Lactobacillus iners and Lactobacillus crispatus. This observation opens up the possibility of harnessing specific bacterial strains in order to prime the vaginal microbiota in the pre- and peri-conceptual periods [13]. Salah, et al. in his study had found that even after controlling for the different variables which influenced the pregnancy rate in patients with PCOD, BV still remained a significant factor impairing the pregnancy rate [2].

Conclusion

Bacterial Vaginosis (BV) is an extremely prevalent vaginal condition and the number one cause of vaginitis among both pregnant and non-pregnant women. It is a new cause of unexplained infertility which has probably been underestimated. The high prevalence of BV in infertile women may suggest either a possible role of BV on fertility or just an association between BV and infertility. It makes sense to at least consider probiotic supplementation as part of a broader lifestyle intervention aimed at improving fertility as the potential for side effects is nearly nonexistent, and there are reasons to think that it could be helpful.

Acknowledgment

The author would like to express his thanks to Mr. Rahul, M Kakalij and Ms. Kanchan Choudhary for helping to inscribe the manuscript.