Bacterial Vaginosis and Methods for Its Diagnosis

Bacterial vaginosis (BV), trichomoniasis, and vulvovaginal candidiasis are three most common infectious causes of vaginitis.  In BV patients, the “normal” and beneficial bacteria dominated by hydrogen peroxide-producing lactobacilli are replaced by the “abnormal” and harmful bacteria such as Gardnerella vaginalis, Mycoplasma hominis, and anaerobes Bactoides spp. and Prevotella spp. If left untreated, BV is known to be associated with endometrititis, pelvic inflammation, and complications of pregnancy, such as chrorioamnionitis and prematurity. In addition BV patients have higher risk to acquire other sexually transmitted diseases.

Bacterial vaginosis can be eradicated if early therapies with effective antibiotics are performed. Accurate and rapid diagnosis of BV is therefore critical for successful treatment of this disease.

In the past the most widely used methods for diagnosis of BV were the Amsel criteria and Nugent score.1,2  These methods have clear limitations in rapid diagnosis because some of the criteria and score either are subjective, complicated to measure, or require special microscopic facility and expertise, which are not readily available in most of the physician offices.

Studies have shown that several bacterial enzymes, particularly neuraminidases (sialidases), are clearly implicated as virulence factors in BV. Neuraminidases cleave specific chemical bonds in bacterial glycoproteins and glycolipids, and release free sialic acid from these biomolecules. A large number of research publications have demonstrated that elevated neuraminidase activity in vaginal fluid is closely associated with BV and that neuraminidase activity exhibited high sensitivity, specificity, positive and negative predictive values for its diagnosis.

Among several compounds developed for detection of neuraminidase activity, IBX-4041 stands out as a sensitive and reliable agent.3 IBX-4041 is a chromogenic (color generating) substrate of neuraminidases. When this compound is incubated with a vaginal fluid sample, it can be hydrolyzed by the neuraminidases contained in the sample to form a dye that displays distinct color change. Different color generated by this procedure indicates levels (low, medium, high) of neuraminidases in the testing sample, which is correlated to the severity of BV.

In 2003, Gryphus Diagnostic, LLC launched BVBlue testing kit for rapid point-of-care diagnosis of bacterial vaginosis. BVBlue contains IBX-4041 as the key ingredient and represents a neuraminidase-based diagnostic method.  Studies have shown that BVBlue kit is a reliable tool in measurement of neuraminidase activity and thereby diagnosis of bacterial vaginosis.

In one study,4 the sensitivity and specificity for the BVBlue group were observed to be 88% and 95% respectively, compared with 88% and 91% for the group using more complex Nugent method. In another study,5 BVBlue test displayed high sensitivity and specificity compared with Amsel method. The sensitivity, specificity, positive and negative predictive values of BVBlue test were respectively 97.6%, 97.5%, 98.4% and 96.3%, whilst those for Amsel criteria were 67.1%, 90.6%, 91.7% and 64.0%. Based on these results and the fact that BVBlue test is much simpler and faster than other existing methods, its benefits in diagnosis and promoting early treatment of BV are quite obvious.

Testing kits containing IBX-4041 as the active ingredient, such as BVBlue and similar products have been used more widely in recent years owing to their rapid speed and reliable result.

Summarized by scientists of LHE Bioscience, Inc.
Updated 07/2021


  1. R Amsel, P A Totten, P A Spiegel, K C Chen, D Eschenbach, and K K Holmes, Nonspecific vaginitis: Diagnostic criteria and microbial and epidemiologic associations, Am. J. Med., 1983, 74:14-22.
  2. R P Nugent, M A Krohn, Hillier S L Hillier, Reliability of diagnosing bacterial vaginosis is improved by a standardized method of gram stain interpretation. J Clin Microbiol. 1991, 29(2):297-301.
  3. S Johnson et al., Chromogenic substrates of sialidase and methods of making and using the same, US6512100B1.
  4. C S Bradshaw, A N Morton, S M Garland, L B Horvath, I Kuzevska, C K Fairley, Evaluation of a point-of-care test, BVBlue, and clinical and laboratory criteria for diagnosis of bacterial vaginosis, J Clin Microbiol., 2005, 43(3):1304-8. F Shujatullah, H M Khan, R Khatoon, T Rabbani, A Malik, An evaluation of OSOM BV blue test in the diagnosis of bacterial vaginosis, Asian Pacific Journal of Tropical Medicine, 2010, 574-576.
  5. F Shujatullah, H M Khan, R Khatoon, T Rabbani, A Malik, An evaluation of OSOM BV blue test in the diagnosis of bacterial vaginosis, Asian Pacific Journal of Tropical Medicine, 2010, 574-576.

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