What do BVAB1, BVAB2 and BVAB3 mean in BV tests?

TL;DR

BVAB1, BVAB2, and BVAB3, recently-discovered bacteria, play a crucial role in diagnosing bacterial vaginosis (BV). These bacteria, part of the Clostridiales order, are highly specific for BV, indicating their significant potential in improving BV diagnosis and understanding. With ongoing research and DNA sequencing, the understanding and classification of these bacteria continue to evolve, offering new insights into BV detection and the microbiology of the vagina.

You may have had a vaginal test result come back that tested positive or negative for the opaquely named ‘BVAB’ species, BVAB1, BVAB2 or BVAB3.​1​

BVAB stands for Bacterial Vaginosis Associated Bacterium

BVAB are recently-discovered bacteria related to or in the Clostridiales order that are highly specific for bacterial vaginosis (BV). BVAB1, BVAB2 and BVAB3 are each a single bacteria.

They are slowly being named and the BVAB name will disappear.

  • BVAB1 Candidatus Lachnocurva vaginae​2​ (candidatis means it’s still a candidate for a real name!)
  • BVAB2 – ?
  • BVAB3 Mageeibacillus indolicus​3​

Because these bacteria are still being classified and their genetics are being traced to determine where they fit in, their names may change or emerge.

The bacteria have been provisionally named using DNA sequencing and matching in DNA libraries.

The research into BVABs

In one research project of 73 vaginal fluid samples with and without BV, BVAB1 was found in 41 per cent of the samples, BVAB2 was found in 89 per cent of samples, and BVAB in 41 per cent of BV vaginal fluid samples.

With information from the DNA libraries, it was found that these three species were highly correlated with bacterial vaginosis.

In two samples where BV tests were negative, but tests for BVAB came back positive for two types, BV developed within a few months of the tests. BVAB2 was found in 89 per cent of the fluid samples with BV.

BVAB bacteria is more specific for BV than Atopobium vaginae, which is highly specific for treatment-resistant recurrent BV, though A. vaginae can exist in vaginas without issue.

References

  1. 1.
    Fredricks DN, Fiedler TL, Marrazzo JM. Molecular Identification of Bacteria Associated with Bacterial Vaginosis. N Engl J Med. Published online November 3, 2005:1899-1911. doi:10.1056/nejmoa043802
  2. 2.
    Holm JB, France MT, Ma B, et al. Comparative Metagenome-Assembled Genome Analysis of “Candidatus Lachnocurva vaginae”, Formerly Known as Bacterial Vaginosis-Associated Bacterium−1 (BVAB1). Front Cell Infect Microbiol. Published online March 31, 2020. doi:10.3389/fcimb.2020.00117
  3. 3.
    Austin MN, Rabe LK, Srinivasan S, Fredricks DN, Wiesenfeld HC, Hillier SL. Mageeibacillus indolicus gen. nov., sp. nov.: A novel bacterium isolated from the female genital tract. Anaerobe. Published online April 2015:37-42. doi:10.1016/j.anaerobe.2014.12.003


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