Bacterial vaginosis gardnerella. Gardnerella: Understanding Bacterial Vaginosis and Its Causative Agent

26.08.202304.07.2023 by alexxlab

What is Gardnerella vaginalis. How does it contribute to bacterial vaginosis. What are the risk factors, symptoms, and treatment options for Gardnerella-related infections. How can Gardnerella infections be prevented and managed effectively.

Содержание

The Role of Gardnerella in Bacterial Vaginosis

Gardnerella vaginalis is an anaerobic bacterium that plays a significant role in the development of bacterial vaginosis (BV), the most common cause of vaginal discharge in women of reproductive age. While Gardnerella is often present in the normal vaginal flora, an overgrowth of this organism can lead to BV, disrupting the delicate balance of vaginal microbiota.

Named after Hermann L. Gardner, who discovered the bacterium in 1955, Gardnerella has been the subject of extensive research due to its association with various health complications. Understanding the nature of this microorganism and its impact on vaginal health is crucial for effective prevention and treatment strategies.

What is the prevalence of Gardnerella vaginalis?

Studies have detected G. vaginalis in up to 50% of women, even in the absence of BV symptoms. This high prevalence suggests that Gardnerella may be part of the normal vaginal flora in many women. However, when it comes to bacterial vaginosis, the estimated occurrence ranges from 5% to 70% of women, with Gardnerella consistently isolated as a key pathogen in these cases.

Pathophysiology of Gardnerella and Bacterial Vaginosis

The pathophysiology of Gardnerella-related infections is complex and not fully understood. However, researchers have identified several key mechanisms by which this bacterium contributes to the development of bacterial vaginosis:

Biofilm formation: G. vaginalis is thought to initiate BV by creating a biofilm that allows other opportunistic bacteria to flourish.
Production of vaginolysin: This pore-forming toxin specifically targets human cells, contributing to Gardnerella’s virulence.
Enzyme activity: Protease and sialidase enzymes associated with Gardnerella aid in its ability to colonize and compete with other vaginal flora.
Adherence to host epithelia: Gardnerella possesses virulence factors that enable it to adhere to vaginal epithelial cells, allowing it to outcompete beneficial Lactobacilli species.

How does Gardnerella disrupt the vaginal microbiome?

In a healthy vaginal environment, Lactobacilli species dominate the microbiome, producing hydrogen peroxide and maintaining an acidic pH that inhibits the growth of potentially harmful bacteria. When Gardnerella overgrows, it disrupts this balance, leading to a reduction in Lactobacilli and an increase in anaerobic bacteria. This shift in the microbial community results in the symptoms associated with bacterial vaginosis.

Risk Factors and Transmission of Gardnerella

While Gardnerella is not traditionally considered contagious, recent research suggests that sexual transmission may play a role in altering the vaginal microbiome. Several factors have been identified that may increase the risk of Gardnerella overgrowth and subsequent bacterial vaginosis:

Frequent tub baths
Douching
Multiple sexual partners
Use of over-the-counter intravaginal hygiene products
Increased frequency of sexual intercourse

It’s important to note that bacterial vaginosis is most common in women of reproductive age, with a higher prevalence observed in African American women compared to Caucasian women. The condition rarely develops in males, highlighting the unique vaginal environment that supports Gardnerella growth.

Clinical Presentation and Diagnosis of Gardnerella-Related Infections

Recognizing the signs and symptoms of Gardnerella-related infections is crucial for timely diagnosis and treatment. While some women may be asymptomatic carriers of Gardnerella, others may experience various symptoms associated with bacterial vaginosis:

Thin, grayish-white vaginal discharge
Fishy odor, especially after sexual intercourse
Vaginal itching or irritation
Burning sensation during urination

How is Gardnerella-related bacterial vaginosis diagnosed?

Diagnosis of bacterial vaginosis typically involves a combination of clinical assessment and laboratory tests. The presence of clue cells—vaginal epithelial cells covered with rod-shaped bacteria—is a characteristic finding in BV. Additionally, healthcare providers may use the Amsel criteria or Nugent scoring system to diagnose BV based on microscopic examination of vaginal secretions and pH testing.

Newer diagnostic techniques, such as PCR-based tests, can detect the presence of Gardnerella and other BV-associated bacteria with high sensitivity and specificity. These molecular methods are becoming increasingly important in accurately diagnosing and managing Gardnerella-related infections.

Treatment Strategies for Gardnerella and Bacterial Vaginosis

Effective treatment of Gardnerella-related infections is essential to alleviate symptoms, prevent complications, and reduce the risk of recurrence. The primary approach to treating bacterial vaginosis involves the use of antibiotics to eliminate the overgrowth of anaerobic bacteria, including Gardnerella.

What are the recommended antibiotic treatments for Gardnerella-related BV?

The most commonly prescribed antibiotics for bacterial vaginosis include:

Metronidazole: Available in oral and intravaginal formulations
Clindamycin: Can be administered orally or as a vaginal cream
Tinidazole: An oral medication that may be used as an alternative to metronidazole

Treatment duration typically ranges from 5 to 7 days, depending on the specific antibiotic and dosage form. It’s crucial for patients to complete the full course of antibiotics as prescribed, even if symptoms improve before the treatment is finished.

Are there alternative treatments for Gardnerella-related infections?

While antibiotics remain the gold standard for treating bacterial vaginosis, research into alternative therapies is ongoing. Some promising approaches include:

Probiotics: Supplementation with beneficial Lactobacilli strains may help restore vaginal flora balance
Prebiotics: Substances that promote the growth of beneficial bacteria in the vaginal microbiome
Bacteriophage therapy: Using viruses that specifically target Gardnerella and other BV-associated bacteria
Natural antimicrobials: Compounds such as boric acid or tea tree oil may have some efficacy in managing BV symptoms

It’s important to note that while these alternative treatments show promise, more research is needed to establish their effectiveness and safety in treating Gardnerella-related infections.

Complications and Health Implications of Gardnerella Infections

Untreated or recurrent Gardnerella-related bacterial vaginosis can lead to various health complications, particularly in pregnant women and individuals at risk for sexually transmitted infections. Understanding these potential consequences is crucial for emphasizing the importance of proper diagnosis and treatment.

What are the potential complications of untreated Gardnerella infections?

Several significant health risks are associated with untreated or persistent Gardnerella-related bacterial vaginosis:

Increased risk of preterm birth in pregnant women
Higher susceptibility to acquiring HIV and other sexually transmitted infections
Increased risk of pelvic inflammatory disease (PID)
Possible complications following gynecological procedures
Potential impact on fertility and reproductive health

These potential complications underscore the importance of timely diagnosis and effective treatment of Gardnerella-related infections. Healthcare providers should be vigilant in screening for BV, particularly in high-risk populations and pregnant women.

Prevention and Management Strategies for Gardnerella Infections

Preventing Gardnerella overgrowth and maintaining a healthy vaginal microbiome is key to reducing the risk of bacterial vaginosis and its associated complications. While complete prevention may not always be possible, several strategies can help minimize the risk of Gardnerella-related infections:

Practice good hygiene: Avoid douching and use of harsh soaps in the genital area
Use condoms: Consistent condom use may help prevent the transmission of Gardnerella between sexual partners
Limit sexual partners: Having multiple sexual partners increases the risk of BV
Avoid irritants: Minimize the use of scented products, bubble baths, and other potential irritants
Wear breathable underwear: Choose cotton underwear and avoid tight-fitting clothing
Maintain a healthy diet: A balanced diet rich in probiotics may support vaginal health
Consider probiotic supplementation: Some studies suggest that oral or vaginal probiotics may help prevent BV recurrence

How can healthcare providers effectively manage Gardnerella-related infections?

Effective management of Gardnerella-related infections requires a comprehensive approach that includes:

Accurate diagnosis using appropriate clinical and laboratory methods
Prompt treatment with appropriate antibiotics or alternative therapies
Patient education on prevention strategies and the importance of treatment adherence
Regular follow-up to monitor treatment efficacy and prevent recurrence
Screening and treatment of sexual partners when appropriate
Consideration of long-term suppressive therapy for women with recurrent BV

By implementing these management strategies, healthcare providers can help reduce the burden of Gardnerella-related infections and improve overall vaginal health for their patients.

Future Directions in Gardnerella Research and Treatment

As our understanding of Gardnerella vaginalis and its role in bacterial vaginosis continues to evolve, researchers are exploring new avenues for diagnosis, treatment, and prevention. Several promising areas of investigation may shape the future of Gardnerella management:

What are the emerging trends in Gardnerella research?

Microbiome-based therapies: Developing treatments that restore and maintain a healthy vaginal microbiome
Biofilm disruptors: Investigating agents that can break down Gardnerella biofilms to enhance antibiotic efficacy
Personalized medicine approaches: Tailoring treatments based on individual vaginal microbiome profiles
Novel antimicrobial compounds: Exploring natural and synthetic compounds with specific activity against Gardnerella
Improved diagnostic tools: Developing rapid, point-of-care tests for more accurate BV diagnosis
Vaccine development: Investigating the potential for vaccines targeting Gardnerella or other BV-associated bacteria

These research directions hold promise for improving our ability to prevent, diagnose, and treat Gardnerella-related infections more effectively in the future. As new discoveries emerge, healthcare providers and patients alike can look forward to more targeted and efficient management strategies for bacterial vaginosis and related conditions.

In conclusion, Gardnerella vaginalis plays a crucial role in the complex ecosystem of the vaginal microbiome. While it can be part of the normal flora, its overgrowth leads to bacterial vaginosis, a common and potentially serious condition. By understanding the biology, epidemiology, and clinical implications of Gardnerella infections, healthcare providers can better address this important women’s health issue. Continued research and innovation in this field will undoubtedly lead to improved outcomes for patients affected by Gardnerella-related infections.

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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Comment on this article.

Figure

Clue cells. Image courtesy S Bhimji MD

References

1.: Hartmann AA. [Gardnerella vaginalis infection. Clinical aspects, diagnosis and therapy]. Urologe A. 1987 Sep;26(5):252-5. [PubMed: 3318083]
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.