Bacterial vaginosis gardnerella. Gardnerella Vaginalis: Causes, Symptoms, and Treatment of Bacterial Vaginosis

29.08.202304.07.2023 by alexxlab

What is Gardnerella vaginalis. How does it cause bacterial vaginosis. What are the symptoms and risk factors of BV. How is bacterial vaginosis diagnosed and treated. Why is BV associated with increased risks during pregnancy and for STIs.

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Understanding Gardnerella Vaginalis and Its Role in Bacterial Vaginosis

Gardnerella vaginalis is an anaerobic bacterium that plays a crucial role in the development of bacterial vaginosis (BV), the most common cause of vaginal discharge in women of reproductive age. Named after Hermann L. Gardner, who discovered it in 1955, G. vaginalis normally resides in the vaginal flora but can cause problems when it overgrows and becomes the dominant species.

While Gardnerella is present in up to 50% of women without BV symptoms, it becomes problematic when the delicate balance of vaginal bacteria is disrupted. This imbalance allows G. vaginalis to thrive, often forming a biofilm that enables other opportunistic bacteria to grow, leading to the development of BV.

Key Characteristics of Gardnerella Vaginalis

Anaerobic bacterium
Part of normal vaginal flora
Can form biofilms
Produces vaginolysin, a pore-forming toxin
Non-spore-forming and non-motile coccobacillus
Gram-variable (can appear gram-positive or gram-negative)

The Prevalence and Epidemiology of Bacterial Vaginosis

Bacterial vaginosis is a widespread condition affecting women of reproductive age. Studies estimate its prevalence to range from 5% to 70% of women, making it the most common vaginal infection in this demographic. The wide range in prevalence estimates likely reflects variations in study populations and diagnostic criteria.

Are certain groups more susceptible to BV? Research indicates that African American women have a higher prevalence of BV compared to Caucasian women. While the exact reasons for this disparity are not fully understood, it may be related to genetic factors, differences in vaginal microbiome composition, or socioeconomic factors affecting healthcare access and hygiene practices.

Factors Influencing BV Prevalence

Ethnicity (higher in African American women)
Age (most common in women of reproductive age)
Sexual activity and number of partners
Hygiene practices (e.g., douching)
Use of intravaginal products
Hormonal changes (e.g., during menstruation or pregnancy)

The Pathophysiology of Gardnerella and Bacterial Vaginosis

The development of bacterial vaginosis involves a complex interplay between Gardnerella vaginalis and other vaginal microorganisms. In a healthy vaginal environment, Lactobacilli species dominate, producing hydrogen peroxide and maintaining an acidic pH that inhibits the growth of potentially harmful bacteria. However, when this balance is disrupted, G. vaginalis can flourish and create conditions favorable for BV.

How does Gardnerella contribute to BV development? The bacterium produces several virulence factors that enable it to colonize the vaginal epithelium and outcompete beneficial Lactobacilli:

Vaginolysin: A cholesterol-dependent cytolysin that can lyse human cells
Proteases and sialidases: Enzymes that break down host proteins and mucus
Adhesion factors: Allow G. vaginalis to attach to vaginal epithelial cells
Biofilm formation: Creates a protective environment for G. vaginalis and other anaerobic bacteria

As G. vaginalis establishes itself, it creates an environment that allows other anaerobic bacteria to thrive. This shift in the vaginal microbiome leads to the symptoms associated with BV, such as increased discharge and a characteristic “fishy” odor.

Clinical Presentation and Diagnosis of Bacterial Vaginosis

Bacterial vaginosis can present with a range of symptoms, although some women may be asymptomatic. The most common symptoms include:

Increased vaginal discharge, often thin and grayish-white
Fishy odor, particularly noticeable after sexual intercourse
Vaginal itching or irritation (less common)

How is bacterial vaginosis diagnosed? Clinicians typically use a combination of clinical findings and laboratory tests to diagnose BV. The Amsel criteria are commonly used and require at least three of the following four criteria to be present:

Thin, homogeneous, white discharge coating the vaginal walls
Vaginal pH greater than 4.5
Positive whiff test (fishy odor when potassium hydroxide is added to a sample of vaginal discharge)
Presence of clue cells on microscopic examination of vaginal fluid

Clue cells are epithelial cells covered with rod-shaped bacteria, giving them a stippled appearance. Their presence is highly indicative of BV. Additionally, Gram staining of vaginal fluid can be used to assess the relative abundance of different bacterial morphotypes, known as the Nugent score.

Treatment Approaches for Gardnerella-Associated Bacterial Vaginosis

The primary goal in treating bacterial vaginosis is to restore the normal balance of vaginal flora. While BV can sometimes resolve on its own, medical treatment is often necessary to alleviate symptoms and prevent complications, especially in pregnant women.

What are the most effective treatments for BV? The current first-line treatments recommended by most guidelines include:

Metronidazole: Available as oral tablets or vaginal gel
Clindamycin: Available as vaginal cream or oral capsules
Tinidazole: An oral antibiotic similar to metronidazole

Typical treatment regimens may involve:

Oral metronidazole 500 mg twice daily for 7 days
Metronidazole 0.75% vaginal gel once daily for 5 days
Clindamycin 2% vaginal cream once daily for 7 days
Oral clindamycin 300 mg twice daily for 7 days
Oral tinidazole 2 g once daily for 2 days or 1 g once daily for 5 days

The choice of treatment may depend on factors such as patient preference, medication allergies, and pregnancy status. It’s important to note that while these treatments are effective in clearing the current infection, recurrence of BV is common, with rates as high as 50% within 12 months of treatment.

Complications and Associated Risks of Bacterial Vaginosis

While bacterial vaginosis is often considered a mild condition, it can lead to significant complications, particularly in pregnant women and those at risk for sexually transmitted infections (STIs). Understanding these risks is crucial for appropriate management and prevention strategies.

What are the potential complications of untreated BV? Some of the most significant risks include:

Increased susceptibility to STIs, including HIV
Pelvic inflammatory disease (PID)
Complications during pregnancy, such as preterm birth and low birth weight
Increased risk of post-surgical infections following gynecological procedures

The association between BV and increased risk of HIV acquisition is particularly concerning. Studies have shown that women with BV are up to 60% more likely to acquire HIV than women without BV. This increased risk is thought to be due to several factors:

Disruption of the vaginal epithelial barrier
Increased inflammation in the vaginal and cervical tissues
Alterations in vaginal pH that may enhance HIV survival
Reduced levels of protective hydrogen peroxide-producing Lactobacilli

For pregnant women, BV is associated with an increased risk of preterm birth, premature rupture of membranes, and postpartum endometritis. These risks underscore the importance of screening and treating BV during pregnancy, particularly in high-risk populations.

Prevention Strategies and Lifestyle Modifications for BV Management

While bacterial vaginosis can be challenging to prevent entirely, several strategies may help reduce the risk of developing or recurrent BV. These approaches focus on maintaining a healthy vaginal microbiome and avoiding factors that can disrupt the natural balance of bacteria.

How can women reduce their risk of developing BV? Some effective prevention strategies include:

Avoiding douching and the use of scented vaginal products
Using condoms consistently during sexual intercourse
Limiting the number of sexual partners
Wearing breathable, cotton underwear
Wiping from front to back after using the bathroom
Considering the use of probiotics, particularly those containing Lactobacillus species

The role of probiotics in preventing and managing BV has gained increasing attention in recent years. While more research is needed, some studies suggest that certain probiotic strains, particularly those containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, may help maintain vaginal health and reduce the recurrence of BV when used in conjunction with antibiotic therapy.

Lifestyle Modifications for BV Prevention

Maintain good hygiene practices without over-cleaning
Avoid tight-fitting, non-breathable clothing
Manage stress levels, as stress can affect vaginal microbiome balance
Consider dietary changes, such as reducing sugar intake and increasing fermented foods
Quit smoking, as it has been associated with an increased risk of BV

It’s important to note that while these strategies may help reduce the risk of BV, they do not guarantee prevention. Women who experience recurrent BV or persistent symptoms should consult with their healthcare provider for personalized management strategies.

The Role of Interprofessional Care in Managing Gardnerella and BV

Effective management of Gardnerella-associated bacterial vaginosis often requires a collaborative approach involving multiple healthcare professionals. This interprofessional care model ensures comprehensive treatment, patient education, and ongoing support to manage acute infections and prevent recurrences.

Who are the key members of the interprofessional team in BV management? The team typically includes:

Primary care physicians or gynecologists for diagnosis and treatment
Nurse practitioners or physician assistants for patient education and follow-up
Pharmacists for medication counseling and management of potential drug interactions
Microbiologists for accurate laboratory diagnosis
Sexual health counselors for addressing related sexual health concerns
Nutritionists for dietary advice that may support vaginal health

The benefits of this collaborative approach include:

Improved diagnostic accuracy through expert interpretation of clinical and laboratory findings
Comprehensive patient education on prevention strategies and treatment adherence
Better management of recurrent BV cases through tailored treatment plans
Enhanced screening and management of associated risks, such as STIs and pregnancy complications
Increased patient satisfaction and outcomes through holistic care

Effective communication between team members is crucial for optimal patient care. Regular case discussions, shared electronic health records, and clear referral pathways can facilitate this collaboration. Additionally, ongoing professional education ensures that all team members are up-to-date with the latest research and treatment guidelines for BV management.

Future Directions in Gardnerella and BV Research

As our understanding of the vaginal microbiome and the role of Gardnerella vaginalis in bacterial vaginosis continues to evolve, several exciting areas of research are emerging. These investigations hold promise for improving diagnosis, treatment, and prevention strategies for BV.

What are some of the most promising areas of research in BV management? Key areas of focus include:

Development of rapid, point-of-care diagnostic tests for BV
Investigation of novel antimicrobial agents targeting Gardnerella biofilms
Exploration of probiotic and prebiotic interventions to maintain vaginal health
Understanding the genetic factors that influence susceptibility to BV
Developing personalized treatment approaches based on individual microbiome profiles

One particularly intriguing area of research is the development of bacteriophage therapy targeting Gardnerella. Bacteriophages are viruses that specifically infect and kill bacteria. Unlike antibiotics, which can disrupt the entire vaginal microbiome, bacteriophages could potentially target Gardnerella more selectively, reducing the risk of recurrence and antibiotic resistance.

Another promising avenue is the exploration of immunological approaches to BV prevention and treatment. Researchers are investigating the potential for vaccines or immunotherapies that could enhance the body’s natural defenses against Gardnerella overgrowth.

Challenges and Opportunities in BV Research

Elucidating the complex interactions within the vaginal microbiome
Developing more effective strategies to prevent BV recurrence
Understanding the long-term impacts of BV on women’s health
Addressing disparities in BV prevalence among different populations
Integrating microbiome research into clinical practice

As research in these areas progresses, it is likely that our approach to managing Gardnerella-associated BV will become more sophisticated and personalized. This could lead to improved outcomes for women affected by this common condition and reduce the associated risks of complications and comorbidities.

In conclusion, Gardnerella vaginalis and bacterial vaginosis represent a significant challenge in women’s health. While current treatments can effectively manage acute infections, the high rate of recurrence and associated risks highlight the need for continued research and innovation. By advancing our understanding of the vaginal microbiome and developing targeted interventions, we can hope to improve the long-term health outcomes for women affected by this condition.

Gardnerella – StatPearls – NCBI Bookshelf

Norah Kairys; Manish Garg.

Author Information and Affiliations

Last Update: August 1, 2022.

Continuing Education Activity

Gardnerella vaginalis is an anaerobic bacterium that is the causative agent in bacterial vaginosis (BV). This bacteria normally is part of the vaginal flora and any overgrowth can cause BV which is the most common cause of vaginal discharge. This activity reviews the evaluation and treatment of Gardnerella and explains the role of the interprofessional team in managing patients with this condition.

Objectives:

Describe the epidemiology of Gardnerella infection.
Identify the typical patient history in those with Gardnerella infection.
Review the use of antibiotics in the treatment of Gardnerella infection.
Outline the importance of improving care coordination among the interprofessional team to enhance the delivery of care for patients affected by Gardnerella infection.

Access free multiple choice questions on this topic.

Introduction

Gardnerella vaginalis is an anaerobic bacterium that resides in the normal vaginal flora.[1] Normally, vaginal flora is predominated by the Lactobacilli species, but when organisms such as Gardnerella begin to overgrow and become the dominant species, this leads to bacterial vaginosis (BV).[1]
Gardnerella was named after Hermann L. Gardner, who discovered the bacterium in 1955.[1] The bacteria are thought to be sexually transmitted between partners and can create a biofilm that progresses into BV.[1] BV is the most common cause of vaginal discharge.[1] Of clinical consequence, BV is associated with preterm birth and increased risk for acquisition of human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs).[1]

Etiology

Although Gardnerella is not considered to be contagious, the role of transmissibility is yet to be completely understood. [2] The spread of this bacteria among individuals through sexual intercourse may alter the natural balance of bacteria within the vagina, and this imbalance can even lead to the development of BV.[2] Typically, BV is caused by a decrease in the number of normal hydrogen peroxide-producing Lactobacilli with an overgrowth of anaerobic bacteria such as G. vaginalis.[2]

Historically, bacterial vaginosis was called G. vaginitis because it was believed that this bacterium caused the condition.[1] However, the newer name helps to highlight the fact that a variety of bacteria that naturally live in the vaginal canal may grow in excess and it is specifically this imbalance that causes this condition.

Factors that may play a role in the development of bacterial vaginosis include frequent tub baths, douching, multiple sex partners, use of over the counter intravaginal hygiene products and increased frequency of sexual intercourse.

Epidemiology

Studies have detected G. vaginalis in up to 50% of women even without symptoms of BV.[3] Thus it has been presumed that Gardnerella may be part of the normal vaginal flora.[3] Additionally, BV is the most common vaginal infection found in women of reproductive age and is estimated to occur in 5% to 70% of women.[3][4] Gardnerella has consistently been isolated as a key pathogen in BV, suggesting a high overall prevalence of Gardnerella in this population.[3]

BV is most common in African American women compared to Caucasians. The condition rarely develops n males. BV is a condition seen in women of reproductive age.

Pathophysiology

Although uncertain, it is thought that most BV infections start with a biofilm created by G. vaginalis which then allows other opportunistic bacteria to grow.[5] Bacterial vaginosis is characterized by the presence of clue cells, which are epithelial cells of the cervix that are covered with rod-shaped bacteria.[6]

G. vaginalis itself produces a pore-forming toxin, vaginolysin, that can only affect human cells. [6] Vaginolysin is a cholesterol-dependent cytolysin that initiates complex signaling cascades that induce target cell lysis and allow for Gardnerella’s virulence.[6] Additionally, protease and sialidase enzyme activities typically accompany this bacterium.[6] Gardnerella has the necessary virulence factors to adhere to host epithelia, which allows it to compete with Lactobacilli for dominance in the vaginal environment successfully.[6] The symptoms of BV are thought to be caused by an increase in normally dormant vaginal anaerobes that create symbiotic relationships with Gardnerella.[6]

Histopathology

Gardnerella is a non-spore-forming, non-motile Coccobacillus.[2] The bacterium can be grown to form small round gray colonies on both chocolate and Human Blood Tween agar.[7] A selective medium for Gardnerella is colistin-oxolinic acid blood sugar.[7]
Gardnerella has a thin gram-positive cell wall but is considered to be gram-variable because it can appear either gram-positive or gram-negative under the microscope due to the varying visibility of this thin cell wall. [7]

History and Physical

Women colonized with G. vaginalis are typically asymptomatic unless they have bacterial vaginosis.[8] Most women with BV present with a complaint of malodorous vaginal discharge, which often becomes more pronounced after sexual intercourse. A diagnosis of BV is suggested by a higher than normal vaginal pH (greater than 4.5), the presence of clue cells on a wet-mount slide, and a positive whiff test.[8] A drop of sodium chloride solution is placed on the wet-mount slide containing some of the swab specimens, and the slide is examined under the microscope for visualization of the characteristic clue cells.[9] The whiff test is performed by adding a small amount of potassium hydroxide (KOH) to the microscopic slide containing the vaginal discharge and is considered to be positive if a characteristic fishy-scent is revealed.[9] Typically, two of these positive tests, as well as the presence of the characteristic discharge, is enough to confirm the diagnosis of BV. [8] If no discharge is present, then all of these criteria are needed to make the diagnosis.[8]

Evaluation

Before the identification of the rapid identification method, the only way to isolate Gardnerella was by growing cultures on selective agar medium.[10] With the advent of the rapid identification method in 1982 (a micro-method based on starch and raffinose fermentation and hippurate hydrolysis), 91.4% of the strains of Gardnerella were able to be isolated without the need for culture and Gram stain.[10]

Occasionally a Gram stain of the vaginal fluid is still done to examine the predominant strain of bacteria to make a microbiological diagnosis of BV. This technique, referred to as Nugent criteria, has a sensitivity and specificity of 89% and 83%, respectively.[10]

Treatment / Management

Asymptomatic Gardnerella colonization does not need to be treated. It has even been reported that up to 30% of cases of BV may even resolve on its own without treatment. [1] However, if a patient is bothered by the symptoms of BV, or is pregnant, it should be treated with either oral or vaginal clindamycin or metronidazole.[1][11]Unfortunately, it has been shown that recurrence may occur in up to 80% of women after treatment.[1][12] If a patient presents with recurrent symptoms, a second course of antibiotics is typically prescribed.[1] A 2009 Cochrane review found tentative but insufficient evidence to support the use of probiotics as treatment or prevention of BV.[13]

Differential Diagnosis

A proper pelvic exam can help to narrow down the differntial diagnosis and exclude other similarly presenting diseases such as herpes simplex virus.[1] Speculum exam can look for cervicitis and a wet mount of the vaginal discharge can determine if there is candidiasis or trichomoniasis.[1] Additional cervical swab cultures can be sent for chlamydia and gonorrhea.[14]

Prognosis

Most uncomplicated cases of bacterial vaginosis resolve with treatment. However, recurrences are not uncommon. Over time, BV is a risk factor for acquiring HIV. Over the past decade, there have been multiple reports of resistant strains that do not resolve with conventional treatment.

Complications

BV can lead to the following:

Increased risk for endometritis and salpingitis
Increased risk of post-surgery infections
Adverse outcomes in pregnancy including premature labor, premature rupture of membranes and postpartum endometritis.
Pelvic inflammatory disease
Neonatal meningitis

Pearls and Other Issues

Untreated BV can lead to increased risk of pregnancy complications and STIs, including HIV.[14] Data also suggest an association between BV and both tubal factor infertility and pelvic inflammatory disease.[15] During pregnancy, BV has been associated with an increased risk of premature birth and miscarriage.[15] It also has been shown to increase the risk of chorioamnionitis, premature rupture of membranes and postpartum endometritis. [15]

Enhancing Healthcare Team Outcomes

Gardnerella is a common genital infection that is often encountered by the emergency department physician, nurse practitioner, internist, and the gynecologist. Asymptomatic Gardnerella colonization does not need to be treated as nearly 30% of cases resolve spontaneously. All symptomatic patients need treatment but despite treatment, recurrences are common.

These patients need to be followed by the nurse practitioner until all symptoms have disappeared.

Even though BV is not a sexually transmitted infection, the nurse practitioner should educate the patient on the importance of safe sex measures, avoidance of multiple sex partners and use of barrier protection.

Review Questions

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Figure

Clue cells. Image courtesy S Bhimji MD

References

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2.: Schwebke JR, Muzny CA, Josey WE. Role of Gardnerella vaginalis in the pathogenesis of bacterial vaginosis: a conceptual model. J Infect Dis. 2014 Aug 01;210(3):338-43. [PubMed: 24511102]
3.: Kenyon CR, Osbak K. Recent progress in understanding the epidemiology of bacterial vaginosis. Curr Opin Obstet Gynecol. 2014 Dec;26(6):448-54. [PubMed: 25304606]
4.: Janulaitiene M, Paliulyte V, Grinceviciene S, Zakareviciene J, Vladisauskiene A, Marcinkute A, Pleckaityte M. Prevalence and distribution of Gardnerella vaginalis subgroups in women with and without bacterial vaginosis. BMC Infect Dis. 2017 Jun 05;17(1):394. [PMC free article: PMC5460423] [PubMed: 28583109]
5.: Machado A, Cerca N. Influence of Biofilm Formation by Gardnerella vaginalis and Other Anaerobes on Bacterial Vaginosis. J Infect Dis. 2015 Dec 15;212(12):1856-61. [PubMed: 26080369]
6.: Baruah FK, Sharma A, Das C, Hazarika NK, Hussain JH. Role of Gardnerella vaginalis as an etiological agent of bacterial vaginosis. Iran J Microbiol. 2014 Dec;6(6):409-14. [PMC free article: PMC4411427] [PubMed: 25926959]
7.: Hardy L, Jespers V, Dahchour N, Mwambarangwe L, Musengamana V, Vaneechoutte M, Crucitti T. Unravelling the Bacterial Vaginosis-Associated Biofilm: A Multiplex Gardnerella vaginalis and Atopobium vaginae Fluorescence In Situ Hybridization Assay Using Peptide Nucleic Acid Probes. PLoS One. 2015;10(8):e0136658. [PMC free article: PMC4548953] [PubMed: 26305575]
8.: Hartmann AA, Elsner P. [Gardnerella vaginalis infection–another sexually transmitted disease]. Hautarzt. 1984 Oct;35(10):512-6. [PubMed: 6389437]
9.: Elsner P, Hartmann AA, Wecker I. [Detection of Gardnerella vaginalis in the pathogen spectrum of sexually transmissible diseases in vulvovaginitis]. Z Hautkr. 1985 Nov 01;60(21):1655-62. [PubMed: 3907172]
10.: Catlin BW. Gardnerella vaginalis: characteristics, clinical considerations, and controversies. Clin Microbiol Rev. 1992 Jul;5(3):213-37. [PMC free article: PMC358241] [PubMed: 1498765]
11.: Menard JP. Antibacterial treatment of bacterial vaginosis: current and emerging therapies. Int J Womens Health. 2011;3:295-305. [PMC free article: PMC3181210] [PubMed: 21976983]
12.: Tosun I, Alpay Karaoğlu S, Ciftçi H, Buruk CK, Aydin F, Kiliç AO, Ertürk M. [Biotypes and antibiotic resistance patterns of Gardnerella vaginalis strains isolated from healthy women and women with bacterial vaginosis]. Mikrobiyol Bul. 2007 Jan;41(1):21-7. [PubMed: 17427549]
13.: Nagaraja P. Antibiotic resistance of Gardnerella vaginalis in recurrent bacterial vaginosis. Indian J Med Microbiol. 2008 Apr-Jun;26(2):155-7. [PubMed: 18445953]
14.: Elsner P, Hartmann AA, Wecker I. Gardnerella vaginalis is associated with other sexually transmittable microorganisms in the male urethra. Zentralbl Bakteriol Mikrobiol Hyg A. 1988 Jul;269(1):56-63. [PubMed: 3140532]
15.: Kasprowicz A, Białecka A. [Gardnerella vaginalis in infections of reproductive organs]. Med Dosw Mikrobiol. 1993;45(2):199-203. [PubMed: 8309297]

: Disclosure: Norah Kairys declares no relevant financial relationships with ineligible companies.
: Disclosure: Manish Garg declares no relevant financial relationships with ineligible companies.