New probe developed to detect specific bacteria associated with bacterial vaginosis

Confocal laser scanning images with 400x magnification of G.vaginalis biofilm in 2 vaginal slides (A and B) in a superimposed image: vaginal epithelial cells in blue and G. vaginalis specific PNA-probe in red. A: vaginal sample with dispersed bacteria; B: vaginal sample with bacteria in biofilm.

Bacterial vaginosis (BV) is a topic we have previously covered on the blog, because of its significance to women’s health. BV is a change in women’s vaginal bacterial composition, in which bacteria that are usually associated with health are at a decreased presence in comparison to BV-associated bacteria. BV is such an issue because it causes a biofilm to form that increase susceptibility HIV and other sexually transmitted infections. BV also has negative effects on pregnancy and is a threat to women of reproductive age. Clearly this is an important topic of research, and was the focus of an article recently published by PLOS ONE.

BV is usually characterized by the presence of Gardnerella vaginalis and Atopobium vaginae. A.vaginae has previously been shown to be much more common than G. vaginalis in BV patients. In the PLOS ONE study, researchers focused on finding the best way to detect these two bacteria in vaginal samples. Samples were taken from 119 women in Rwanda, between the ages of 18 and 35 years old. After testing multiple different probes that had been developed by the researchers, they found that something called the PNA FISH is a very good tool for detecting bacteria in biofilms. Through this study the scientists were able to detect that higher quantities of G. vaginalis and A. vaginae are associated with bacterial biofilms. Almost half the samples containing G. vaginalis also contained A. vaginae, whereas all of the samples that contained A. vaginae were also positive for G. vaginalis.

With the data collected, the researchers hypothesize that G. vaginalis is a main cause of vaginal biofilms when it is high enough in concentration. Hopefully with the discovery of effective probes, much more can be discovered about bacterial vaginosis.    

Vaginal microbiome once again tied to preterm birth

Preterm birth is major global health challenge.  Today, around 11% of all babies are born prior to 37 weeks, and are considered preterm.  Many of the causes of these preterm births are still unknown, but it is thought that around 25% of them may be related to a bacterial infection that comes from somewhere in the mother’s own body, i.e. her microbiome.  Many studies are now linking specific vaginal bacteria to risk of preterm birth, and other studies have even shown a connection between other microbiome sites, such as the gut and oral microbiome.  Unfortunately, studies on the microbiome and preterm birth are extremely difficult to conduct, so there are just not enough to have any sort of scientific consensus on the topic.  Last week though, a very rigorous study out f Stanford University was published in the Proceedings of the National Academy of Sciences that monitored expectant mothers vagina, gut, and oral microbiome throughout the course of her pregnancy and then for one year after.  Among many interesting findings, which are discussed below, the most important one was yet another connection between bacterial vaginosis and preterm birth.

The researchers monitored the vaginal, distal gut, salivary, and tooth/gum microbiomes of 49 women, 15 of which ended up delivering preterm, over the course of their pregnancy and for one year after.  Interestingly, the non-vaginal sites’ microbiomes remained relatively stable over the duration of the pregnancy, and even for the one year after.  The vaginal microbiome, however, did show some differences during and after pregnancy.

As many of our readers already know, a healthy vaginal flora is dominated by Lactobacilli, but around 20% of American women are dominated by other species, such as Gardnerella vaginalis, and have an overall increased vaginal diversity.  These women have what is known as community state type four, or CST4, and these women could be diagnosed with bacterial vaginosis (BV), though the clinical diagnosis is not so specific.  The other community state types, CST1, 2, 3, and 5, are dominated by different strains of Lactobacilli, and are generally regarded as healthy.  This current research showed that many of the women’s vaginal microbiomes actually shifted between various CST’s during pregnancy, most often shifting to and from CST4.  These transitions had no association with preterm birth, though.  After giving birth the vaginal microbiome became more diverse, and had greater abundances in anaerobic bacteria, such as Peptoniphilus, Prevotella, and Anaerococcus.  In addition, this usually coincided with a decrease in Lactobacilli.  Surprisingly, these changes did not seem to relate to mode of delivery (C-section of vaginal).

CST4 has been linked to preterm birth before, and this was reinforced in this study.  The scientists found that the longer a women’s vaginal microbiome was within CST4, the greater risk she had for preterm birth.  In addition, the abundance of Gardnerella and Ureaplasma, specifically, were linked to preterm birth.

This study reinforces what many microbiome scientists already suspect, and that is the importance of the vaginal flora in preterm birth.  It is unclear at this point if manipulating the vaginal flora prior to, or during pregnancy would help prevent preterm birth, but it is certainly worthy of discussion and clinical testing.  If you are reading this and wondering what your vaginal microbiome is, then we recommend you participate in the citizen science project, YourPrivateBiome, to find out.  You can learn more about it by following this link on our site, or just click the link above.

New contraceptive vaginal ring does not increase risk of vaginal infections

The Nuvaring, a type of vaginal ring.

A newly developed contraceptive device that consists of a vaginal ring that is meant to be used for an entire year is currently under development.  As part of this device’s safety trials the scientists who developed the device monitored how it would impact the vaginal microbiome.  The vaginal microbiome is critical to vaginal health, and certain changes to the vaginal flora are associated with bacterial vaginosis (BV), yeast infections, and other vaginal diseases.  Implanting devices will certainly affect the vaginal microbiome, but fortunately, the scientists determined that the device did not increase the likelihood of getting a vaginal microbiome-mediated disease.  They published their results last week in PLoS ONE.

The vaginal microbiomes of 120 women using the device were measured over the course of a year.  There were no significant increase in the rates of BV over the course of the year.  In addition, the levels of Lactobacilli, which are associated with a healthy vagina, and Gardnerella vaginalis, which has been associated with BV, remained relatively unchanged over the course of treatment.  In addition, measurements on the actual surface of the vaginal ring matched the overall vagina quite well in terms of microbial colonization. In both cases, Lactobacilli dominated.

Any fluid or device inserted into the vagina should be considered for its effect on the vaginal microbiome, for example, douching is associated with BV.  Fortunately, this safety study showed that the vaginal ring did not increase rates of disease, so women out there using a vaginal ring for contraception need not be too concerned that their ring is negatively impacting their vaginal health.

Bacterial vaginosis associated bacteria may increase a women’s risk for miscarriage

Bacterial infections or even slight imbalances can be damaging at many difference locations in the human body. One that should be taken seriously in bacterial vaginosis, which is an infection in females where a healthy bacterial balance is taken over by bacteria such as Gardnerella vaginalis, Ureaplasma urealyticum, and Mycoplasma hominis to name a few. Meanwhile, the presence of Lactobacillus crispatus and Lactobacilus iners would be characteristic of a normal vaginal microbiome. In a study out of Philidelphia, Pa that was recently published by Maternal and Child Health Journal, researchers inspected a possible connection between bacterial vaginosis and pregnancy miscarriages.

          A total of 418 pregnant women were included in the study. 65% of the women were African American, 27% were Hispanic, and 4% were Caucasian. Women were eligible if they were seeking treatment prior to 14 days of gestation, if they were not pregnant with multiples, and if there were no issues in terms of ectopic or molar pregnancy. Swabs were collected from the women and analyzed. During this study, 74 women experienced a miscarriage, while 344 delivered at term.

          It was found that the group of women who had miscarriages were older than those who did not. Women with high concentrations of Bacterial Vaginosis-Associated Bacterium 3 (BVAB3) before 2 weeks gestation had a 20% increased chance of miscarriage. On the other hand, for each one unit increase in Leptotrichia/Sneathia species concentration, risk of miscarriage decreased by 20%, and for that of Megasphaera phylotype 1-like species risk decreased by 19%. The implications of this type of research could be very beneficial to women everywhere. More knowledge like this could hopefully one day lead doctors towards even better care for pregnant women. Ideally, with more research into this area, the prevalence of miscarriages could be lowered.