Bacterial Vaginosis (Part 2 of 3)

BV Risk Factors, Health Impacts, Current Antimicrobial Therapeutics, and Resistance

Angela Kelly, MA and Michael Stanclift, ND
This is part two in a three-part series about bacterial vaginosis (BV). In part one we discussed a healthy vaginal microbiome, BV’s characteristics, and diagnostic criteria. In this section, we’ll explore risk factors for developing BV, the health impacts of it, and current conventional therapies.

BV risk factors
While the precise causes of BV are still being investigated, researchers have discovered the following risk factors that can contribute to its development:

• Having a sexual partner with a history of BV1
• Douching2-3
• Smoking4-5
• Recent antibiotic use5-6
• Being a Black or Mexican-American woman1,3,7-9
• Menstruation2,5,10-11
• Pregnancy5,12
• Having an IUD (especially copper)13
• New sexual partner(s)—result in a 2.5-fold increased risk1,4
• Uncircumcised sexual partner(s)4,14
• Inconsistent condom use4
• Previous STI diagnosis15-16Having female sexual partners or both female and male sexual partners1,4,17
• Becoming sexually active at 14 years of age or younger18
• Socioeconomic status5,19
• Chronic stress20-21
• Obesity22

Health impact of BV
Although most cases of BV are asymptomatic, BV can still have devastating health consequences. Even without symptoms, BV can cause:

• Genital inflammation23
• Increased risk of contracting and passing STIs, including a 60% increase in the acquisition of HIV23-30
• Impaired healing of the epithelial barrier11,31
• Increased risk of HPV infection and resulting cervical cancer11,32
• Infertility33-35
• Increased risk of pelvic inflammatory disease (PID)36-38
• Failure of in vitro fertilization39
• Miscarriage12,39,40
• Amniotic fluid infection41
• Preterm birth42-44,45-46
• Postsurgical infections47

Beyond the raised physical health risks, BV is associated with a significant negative impact on self-esteem, sexual relationships, and quality of life.48 Women report feelings of shame, stress, anxiety over loss of control over recurrent infections, and fear of others’ detection of odor or discharge. With approximately 29% of women in the US suffering from BV, more effective and lasting treatments are needed to reduce the health and economic burden of bacterial vaginosis.22

Current antimicrobial therapeutics and resistance
Current antimicrobial therapeutics often provide only temporary relief and ultimately contribute to antibiotic resistance. BV is usually treated with metronidazole, clindamycin, or a combination of oral and intravaginal antibiotic therapies.49Occasionally other antibiotics such as rifaximin, secnidazole, and tinidazole are prescribed.49-51 A 2020 in vitro study showed clindamycin had greater initial effectiveness against G. vaginalis than metronidazole; however, clindamycin is strongly associated with antibiotic resistance.52-53 In a randomized clinical trial 17% of cases had baseline clindamycin resistance, and 53% showed resistance to it after therapy.53 Also of consideration, clindamycin has been linked to Clostridioides difficile (C. diff) colonization and pseudomembranous colitis.13,50,54 Studies demonstrate G. vaginalis and A. vaginae also show resistance to metronidazole, although to a lesser extent than clindamycin.52,55 When metronidazole is used to treat BV, it can break up the biofilm created by G. vaginalis and A. Vaginae; however, live cells can persist within the biofilm, allowing for recurrences.56 Microbial profiling shows metronidazole temporarily reduces vaginal microbial diversity, and the reestablished microbiota rarely returns to a balanced lactobacilli-dominant state.57 Treatment with metronidazole frequently causes the adverse effects of nausea, vomiting, GI disturbances, and metallic taste.54,58 Occasionally metronidazole may also cause seizures, peripheral neuropathy, transient neutropenia, and allergic reactions, including anaphylaxis.58

These findings highlight that effective and lasting treatments for BV are urgently needed. The pipeline of antibiotics continues to dwindle, and bacteria grow more resistant with the antibiotic treatment of each episode.59 The treatment of protracted or recurring cases of BV often results in a revolving door of relapses for patients.59 Identifying lasting treatments for BV that rely less on antibiotics is of the utmost urgency.60,61

BV recurrence after antimicrobials
The recurrence rate following treatment of BV with antibiotics is high, with a study revealing that 58% of participants experienced a recurrence within a year and 69% returned to abnormal vaginal profiles.50,58  The high rate of recurrence appears to be multifaceted, linked to biofilms created by G. vaginalis and A. vaginae, impaired immune system response, antibiotic resistance, hygiene practices, and, according to some researchers, sexual transmission and reinfection by a woman’s sexual partner(s).60-63 Although there are variations in studies, a recent study showed improved BV recurrence rates when male partners were treated with oral and topical antibiotics. More research on the efficacy of treating sexual partners is needed.64 Having an untreated sexual partner is linked to a raised risk of recurrence of BV, although more research is needed.63,65
We can see the contributing factors for BV are multifactorial and that simple antimicrobial therapies are failing the majority of women they are prescribed to help. In our next and final installment in this series  we’ll explore alternative and emerging treatments for BV, including the role of probiotics. We’ll see how a problem characterized by microbial overgrowth may ultimately need more microbes to see its resolution.
Citations

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