Bacterial Vaginosis & Trichomoniasis: Key Aspects on Different Diagnostic Methods
Thursday, May 04, 2023
by Jeff Reid, Sr. Commercial Manager at SEKISUI Diagnostics
Each year, millions of women of all ages and backgrounds are impacted by vulvovaginal disorder, making it the main cause for health care visits by women in the United States.1 This disorder usually occurs due to an infection or when the bacterium in the vagina becomes unbalanced. Two common causes of vulvovaginal disorder are Bacterial vaginosis and Trichomoniasis.
Bacterial vaginosis and Trichomoniasis are linked to a broad range of associated health complications, from preterm birth to an increase in Sexually Transmitted Infections (STIs).2,3 If immediately diagnosed and treated, the risk of associated health complications can be greatly minimized. Therefore, a “test and treat” approach is critical to take when diagnosing Bacterial vaginosis and Trichomoniasis. Key considerations on different diagnostic methods for Bacterial vaginosis and Trichomoniasis will be reviewed in this editorial.
Bacterial vaginosis occurs when the healthy balance of vaginal bacteria is disrupted by an overgrowth of pathogenic bacteria. It is the most prevalent form of all vulvovaginal disorder, resulting up to 50% of all cases.1
Common symptoms of Bacterial vaginosis consist of the following:2
- A thin white or gray vaginal discharge
- Pain, itching, or burning in the vagina
- A strong fish-like odor, especially after sex
- Burning when urinating
- Itching around the outside of the vagina
There are serious health complications associated with Bacterial vaginosis, including the increased risk of contracting several different STIs. Therefore, all women suspected of having Bacterial vaginosis should be evaluated for Human Immunodeficiency Virus (HIV) and other STIs.1
Common diagnostic methods for Bacterial vaginosis consists of Nugent scoring from a vaginal Gram stain, Amsel’s Criteria, molecular tests, and rapid point-of-care tests.4
Nugent scoring from a vaginal Gram stain is considered the gold standard for diagnosing Bacterial vaginosis.4 It consists of performing a Gram stain where the vaginal specimen is smeared on a glass slide. Then the vaginal smear is evaluated under a microscope according to the Nugent scoring system. The Nugent score is calculated by assessing for the presence of large gram-positive rods (Lactobacillus morphotypes; decrease in Lactobacillus scored as 0 to 4), small gram-variable and gram-negative rods (G. vaginalis and Bacteroides morphotypes; scored as 0 to 4), and curved gram-variable rods (Mobiluncus spp. morphotypes; scored as 0 to 2).4 Although considered the gold standard, there are challenges associated with Nugent scoring from a vaginal Gram stain. For example, a Gram stain is a multistep process that requires significant hands-on activities and is usually performed in a laboratory setting. Also, the method is considered a Provider-Performed Microscopy (PPM) procedure, which is a complex procedure that requires a specific skillset to perform. Due to the significant hands-on activities of the process and the complexity of the procedure, Nugent scoring from a vaginal Gram stain does not allow for a test and treat approach.
Amsel’s Criteria is a traditional diagnostic method based on microscopy and clinical symptoms. The method is based on the presence of 3 of the following criteria:4
- Discharge: homogeneous, thin, white-gray discharge that smoothly coats the vaginal walls
- Clue cells: more than 20% clue cells on saline microscopy
- pH >4.5: vaginal fluid pH >4.5
- Positive KOH: positive KOH whiff test result
Diagnosing Bacterial vaginosis by Amsel’s Criteria can be time consuming and it is prone to subjectivity as there are multiple steps involved. Like Nugent scoring from a vaginal Gram stain, Amsel’s Criteria is considered a Provider-Performed Microscopy (PPM) procedure, which is a complex procedure that requires a specific skillset to perform. Due to the multiple steps of the process and the complexity of the procedure, Amsel’s Criteria usually does not allow for a test and treat approach.
There are different molecular tests available for diagnosing Bacterial vaginosis, which detect specific bacterial nucleic acids. The sensitivity and specificity of these tests are high, allowing for accurate test results. However, the methodology requires highly expensive and sophisticated instrumentation that require a specialized skillset to perform, making it hard for health care providers to adopt the technology into their practice.
The Centers for Disease Control and Prevention (CDC) notes that the OSOM® BVBLUE® test in their 2021 Sexually Transmitted Infections Treatment Guidelines as a recommended rapid point-of-care test for diagnosing Bacterial vaginosis.4 Unlike Nugent scoring from a vaginal Gram stain and Amsel’s Criteria, the OSOM® BVBLUE® Test is CLIA-waived and does not require a specific skillset. Also, unlike molecular tests, the OSOM® BVBLUE® Test does not require specialized instrumentation to perform. It is a visual read, enzymatic activity assay that detects the sialidase enzyme of bacterial pathogens. The test can be performed at the point-of-care and the results are produced in 10 minutes, allowing for a test and treat approach.
Trichomoniasis is a parasitic infection caused by a protozoan parasite called Trichomonas vaginalis. It is considered the most curable, non-viral sextually transmitted disease, with an estimated 3.7 million cases per year in the United States.6 It is estimated that up to 35% of all vulvovaginal disorders are caused by Trichomonas vaginalis.1
Common symptoms of Bacterial vaginosis consist of the following:3
- A thin clear, white, yellowish, or greenish vaginal discharge
- Itching, burning, redness or soreness of the vagina
- An unusual fishy smell
- Discomfort with urination
The health complications associated with Trichomoniasis consists of an increased risk of getting or spreading other STIs, a greater chance of preterm birth, an increased risk of cervical cancer.3
Common diagnostic methods for diagnosing Trichomoniasis consists of wet-mount microscopy, culture followed by wet-mount microscopy, molecular tests, and rapid point-of-care tests.5
Wet-mount microscopy has traditionally been used to diagnose Trichomoniasis. The method consists of collecting a vaginal specimen and examining it for motile organisms, called trichomonads, under a microscope. It is important to note that the specimen should be immediately examined after collection as 20% of trichomonads lose their motility within 10 minutes of specimen collection.7 Wet-mount microscopy is a relatively inexpensive method and can be performed at the point-of-care. However, the sensitivity can be relatively low, leading to an increase in false negative tests results.5
Culture followed by wet-mount microscopy is a more sensitive test method than wet-mount microscopy.5 Prior to examining the specimen under a microscope for trichomonads, the specimen is inoculated and incubated for 2-5 days. The primary challenge with this method is the time it takes to incubate the specimen, resulting in a disrupted quality of life for the patient.
Molecular tests are considered the gold standard for diagnosing Trichomoniasis. These are highly sensitive tests that detect the genetic material of the parasite, called Trichomonas vaginalis. Although these tests are highly accurate, they require highly expensive and sophisticated instrumentation that usually require a specialized skillset to perform, making it hard for health care providers to adopt the technology into their practice.
The CDC notes the OSOM® Trichomonas Test in their 2021 Sexually Transmitted Infections Treatment Guidelines as a recommended rapid point-of-care test for diagnosing Trichomonas.5 The OSOM® Trichomonas Test is a visual read, lateral flow antigen test that detects the protein of trichomonas called Trichomonas vaginalis. It is a CLIA-waived test that can be performed at the point-of-care, allowing for a test and treat approach. The sensitivity of the OSOM® Trichomonas Test compares favorably to the molecular tests with reported sensitivities of 83%-90%.6
Vulvovaginal disorder is a common condition that can drastically impact the quality of life for women. It is a disorder that is responsible for 10 million physician visits per year.1 Bacterial vaginosis and Trichomoniasis are two common causes of vulvovaginal disorder, which both have a mix of symptoms and associated health complications. To overcome the disrupted quality of life for women and the associated health complications, a test and treat approach should be taken when diagnosing Bacterial vaginosis and Trichomoniasis. There are only a few diagnostic options that allow for such approach, which are the OSOM® BVBLUE® Test and the OSOM® Trichomonas Test. The CDC notes both tests in the 2021 Sexually Transmitted Infections Treatment Guidelines as diagnostic considerations for Bacterial vaginosis and Trichomoniasis. Both tests have high sensitivity and specificity compared to the gold standard methods and allow for a test and treat approach.
- Brown, H. Improving the Diagnosis of Vulvovaginitis. Population Health Management. Vol. 23, suppl 1, 2020.
- Fact Sheet - Bacterial Vaginosis. 2017
- Fact Sheet - Trichomoniasis. 2017
- Sexually Transmitted Infections Treatment Guidelines, Bacterial Vaginosis. 2021
- Sexually Transmitted Infections Treatment Guidelines, Trichomoniasis. 2021
- C. Rapid and Point-of-Care Tests for the diagnosis of Trichomonas vaginalis in women and men. Sex Trans Infect. 2017.
- Kingston MA, Bansal D, Carlin EM. ‘Shelf life’ of Trichomonas vaginalis. Int J STD AIDS. 2003 Jan;14(1)