As a prelude to this article – I just want to explain that this particular article regarding the human microbiome, although obscure at first, ties in later to other areas that affect human health and dieting decisions. I will incorporate that information in time, but I decided to start with this particular aspect due to new information that is coming out and how such a seemingly obscure issue like bacteria in the vagina could possibly have any impact on you. For pregnant women and their newborns, it certainly does since pre-term labor is costly to society and on a personal level. Also, what is alluded to in the articles below are that a number of modifying issues combine together to create an outcome. For example, poor dental hygiene may have an association with fetal outcomes and general health. Likewise, the mother’s microbiome is affected by antibiotic use and is passed down to the neonate during delivery. This external influence impacts the long term health of the child. I’m sorry if this article is not ‘sexy’ but it ties in to a longer running discussion. In an age of increasing use of probiotics and antibiotics, this type of information is evidence-based and not testimonial in nature. It will hopefully lead to a healthier outcome. – 10/10/2015
I’m going to discuss some research into microbiome-related information that has implications in quite a few areas. Of course, the latest raging research has involved increasing data regarding the trillions of bacteria that are a part of our bodies and the results of alterations in their composition. Over time, I will be writing about various evidence-based research and implications they may have for our health. One area that I see as under-served in the general health maintenance is dental care. I see a great connection with poor dental care and the possibility that it increases the rate of bad outcomes in pregnancy as related to the microbiome composition in individuals with periodontal disease during pregnancy. Of course medicaid and other insurance covers for health maintenance in other ways, but rarely does it cover dental care in the general public. It is expensive to have teeth and maintain them with general care. Between regular checkups, fillings, root canals, and crowns, a single tooth can cost several thousand dollars to spare! Hence, many people have bad teeth and bad bacteria in their mouths, which leads to generalized inflammation throughout the body. JAMA just revealed a piece in the latest issue linked below that discusses premature labor and it’s relationship to the microbiome. One study cited in the article made a clear observation of the association with dental bacteria and premature labor and poor outcomes in neonates: Here is the PDF link below:
The basic research is pointing more and more at general inflammation as a cause of many human illnesses. This inflammation comes from many sources. This is one more example of the association of that inflammation as related to our microbiome and poor outcomes. Let’s discuss the article:
One of the primary research articles cited in the JAMA essay included this one:
- The United States has one of the highest rates of pre-term birth, at 12%, it is higher than Canada, Mexico, Europe, and many Latin American Nations.
- Pre-term birth is a leading cause of death and neurological disability.
- Bacteria can invade the amniotic cavity to set up infection and inflammation that results in early delivery. In the article above, bacterial DNA from the vagina, gut, and oral area have been found in the amniotic fluid. The MORE DNA found, the earlier the delivery.
- Higher levels of Lactobacillus in the vaginal area are associated with better outcomes of the fetus and less pre-term delivery.
- In the study above, samples from the vagina, saliva,stool, and gums were taken in 9 week intervals from 40 women who were pregnant and outcomes were followed. Of the samples, 62% were Lactobacillus-poor and this was inversely correlated with gestational age at delivery. In other words, a UNhealthy oral, gut, and vaginal microbiome was associated with pre-term delivery. In fact 75% of the subjects who had Lactobacillus dominant vaginal microbiota had a term pregnancy that was normal.
- Microbial Invasion of the amniotic cavity (MIAC) in pre-mature rupture of the membranes (which results in early delivery) was discovered in half of the test subjects when using MOLECULAR PCR techniques , whereas it was found only in 34 % by culture. In other words, past research missed bacterial invasion on the amniotic fluid in past studies and underrepresented the importance and types of bacteria that cause and result in pre-term delivery.
- It appears that Lactobacillus specied protect against poor pregnancy outcomes by producing proteins and lactic acid which modifies the immune response and promotes vaginal health during pregnancy.
- It was found that by using molecular techniques, the number of invading species of bacteria was some 46 species-level phylotypes, whereas culture historically showed only 14 species. Also, new , uncultivated taxa were discovered to be involved. Included in taxa detected by PCR were some species associated with the gastrointestinal tract (Coprobacillus sp.), the mouth (Rothia denticariosa) and the vagina in the setting of bacterial vaginosis (Atropobium vaginae).
- If a person’s PCR molecular test was positive for bacteria, the chance of getting a uterine infection during pregnancy (choramnionitis) was at a risk of 2.1, whereas a positive culture showed a risk of 2.0. Also found was that bacterial rDNA abundance was in a dose relationship with gestational age delivery, meaning that more bacterial DNA detected by PCR was associated with pre-mature birth.
- The strength of the PCR findings was bolstered by the association of higher inflammatory WBC counts in amniotic fluid, as well as IL-6, another marker of inflammation. Patients with positive culture and PCR results (molecular based study) had even higher levels of WBC and IL-6 markers than PCR positive cases alone. The risk of choramnionitis was trending higher in patients with positive PCR results than in those with just positive culture results. The bottom line is the presence of PCR (molecular study) evidence of bacteria, culture evidence of bacteria, or both significantly increased the risk of uterine infections and pre-term delivery.
- The study also included a correlation with bacterial 16 S rRNA gene copy number, which also, when elevated, was correlated with earlier gestational age, meaning pre-term birth.
- A negative amniotic fluid culture with a positive PCR for bacteria was associated with a lower mean birthweight and higher amounts of respiratory distress and necrotizing enterocolitis (infected dead bowel) in neonates. This shows the power of PCR analysis relative to culture.
- The key findings in pre-term deliveries from this are: (1) Microbial Invasion of the amniotic cavity (MIAC) affected half of all those with pre-term delivery, yet this was frequently missed by regular culture results (2) diverse microbes cause pre-term birth. Many of the bacteria were from new phyla and have not been cultivated before. (3) Some of the invasion is a result of gastrointestinal microbes (4) Candida yeast infection was also present more frequently in premature delivery than in prior studies, specially when an IUD had been used. (5) The more microbial DNA present, the earlier the delivery (6) The fetus has an inflammatory response to the infection reflected in IL-6 and WBC counts in the amniotic fluid, (7) Culture of the amniotic fluid demonstrates infection 34% of the time in pre-term delivery, whereas PCR detects bacterial invasion 50% of the time in pre-term delivery.
- This is the first study to demonstrate gastrointestinal tract bacteria as a source of microbes in amniotic fluid.
- PCR also detected a periodontal source of infection, which was a TM7 member of bacteria that is associated with peridontitis (dental gum infection) and bacterial vaginosis (vaginal infection)
- The study goes on to identify three Taxa of bacteria that they identified as being associated with pre-term delivery: (1) Atopobium sp, DIalister sp, and Peptoniphilus sp. which cause bacterial vaginosis, an infection associated with premature rupture of the membranes (2) A taxa associated with oral cavity bacteria, which include Filifactor alocis (endodontic infections) and Rothia dentocariosa (associated with odontogenic abscesses and fetal death) In other words, BAD TEETH may be leading to poor fetal outcomes and premature delivery. (3) Myroides spp implicated in urogenital disease and endocarditis. Also noted is that Candida infection (yeast), especially in the setting of an IUD (intrauterine device) is associated with premature birth due to biofilm formation.
- Bottom line: Positive PCR for bacteria in amniotic fluid is associated with earlier birth rates. Elevated levels of amniotic fluid of bacterial rDNA is also associated with premature delivery. Higher levels of fetal IL-6 and histological inflammation of fetal membranes is also associated with pre-term delivery. This particular study demonstrated that prior MIAC cases may have been misclassified as being free of microbia invasion or being monomicrobial, when in fact they were not.
The abstract of the Nature article is below:
The composition and structure of the pregnancy vaginal microbiome may influence susceptibility to adverse pregnancy outcomes. Studies on the pregnant vaginal microbiome have largely been limited to Northern American populations. Using MiSeq sequencing of 16S rRNA gene amplicons, we characterised the vaginal microbiota of a mixed British cohort of women (n 5 42) who experienced uncomplicated term delivery and who were sampled longitudinally throughout pregnancy (8–12, 20–22, 28–30 and 34–36 weeks gestation) and 6 weeks postpartum. We show that vaginal microbiome composition dramatically changes postpartum to become less Lactobacillus spp. dominant with increased alpha-diversity irrespective of the community structure during pregnancy and independent of ethnicity. While the pregnancy vaginal microbiome was characteristically dominated by Lactobacillus spp. and low alpha-diversity, unlike Northern American populations, a significant number of pregnant women this British population had a L. jensenii-dominated microbiome characterised by low alpha-diversity. L. jensenii was predominantly observed in women of Asian and Caucasian ethnicity whereas L. gasseri was absent in samples from Black women. This study reveals new insights into biogeographical and ethnic effects upon the pregnancy and postpartum vaginal microbiome and has important implications for future studies exploring relationships between the vaginal microbiome, host health and pregnancy outcomes
The microbiome in the vaginal area has bacteria that are believed to inhibit pathogen growth through secretion of antibacterial bacteriocins as well as the production of metabolites such as lactic acid that help to maintain a low, hostile pH6 . Dysbiosis of the vaginal microbiome is associated with complications of pregnancy, in particular an increased risk of preterm birth. The maternal vaginal microbiome may also be an important source of pioneer bacteria for the neonatal gut microbiome.
In asymptomatic non-pregnant North American women of reproductive age, five vaginal bacterial community state types (CSTs) have been defined. Four of these are dominated by Lactobacillus species including L. crispatus (CST I), L. gasseri (CST II), L. iners (CST III), and L. jensenii (CST V). CST IV is typically characterised by low levels of Lactobacillus spp. and increased diversity of anaerobic bacteria including Prevotella, Dialister, Atopobium vaginae, Gardnerella vaginalis, Megasphaera, Peptoniphilus, Sneathia, Finegoldia, and Mobiluncus. The latter species are often associated with bacterial vaginosis, a clinical syndrome of vaginal discharge and odour characterised by polymicrobial overgrowth, which is linked to an increased risk of preterm birth, and histological chorioamnionitis. Interestingly, in American populations, vaginal bacterial communities dominated by Lactobacillus spp. (CST I, II, III and V) are most frequently observed in Asian and White women whereas a diverse microbiome (CST IV) is more frequently observed in Black and Hispanic populations suggesting that the composition of the vaginal microbiome may be, in part, shaped by genetic differences between hosts but cultural and behavioural factors cannot be excluded to explain these associations.These findings have been recently confirmed and extended by Fettweis and colleagues who identified clear ethnic related differences in the vaginal microbiome of a large population of healthy Black and White Northern American women
The above is part if Nature’s article.
- Lactobacillus plays a role in keeping the microbiome acidic and stable during a pregnancy. Apparently estrogen levels rise through placental production and this results in the growth of Lactobacillus through increased glycogen stores in the vagina. This glycogen is broken down by alpha amylose into maltose, maltotriose, and maltotetraose, which all support Lactobacillus. After pregnancy, estrogen drops rapidly and so does Lactobacillus. Of note, endometritis ( a uterine infection ) occurs more commonly at this time. ” Culture based methods have shown early postpartum endometritis is typically characterized by the presence of multiple microbiota often associated with bacterial vaginosis including Gardnerella vaginalis, Peptococcus spp., Bacteroides spp., Staphylococcus epidermidis, Streptococcus agalactiae and Ureaplasma urealyticum. “
- In the Nature article above, it was noted that there are geographical and ethnic differences in the vaginal microbiomes during pregnancy, and that needs to be accounted for in studies. For example, it was noted that women with a L. gasseri dominated microbiome had the fastest HPV remission rate whereas those with reduced Lactobacillus spp. and increased Atopobium had the slowest remission rate during pregnancy.
- The bottom line is that during pregnancy, the vaginal microbiome becomes less diverse and more stable with Lactobacillus, but the actual population of Lactobacillus varies by the ethnicity and background of the person.
Why is understanding the microbiome, even in a crazy place like the vagina so important? Because, complications of prematurity account for 29% of global neonatal deaths (approximately 1 million) each year and 3.1% of total disability adjusted life years in the global burden of disease. Of course a variety of causes of prematurity exist such as uteroplacental ischemia, cervical disease, decidual hemorrhage, and stress. Evidence is accumulating that both labor and pre-term labor are initiated by a cascade of pro-inflammatory changes. Labor-associated inflammatory changes are characterized by immunocyte infiltration and significant increases in the expression of interleukin (IL)-1β, IL- 6, IL-8, monocyte chemoattractant protein (MCP)-1, and tumor necrosis factor (TNF)-α expression in the fetal membranes, cervix, amniotic fluid, and placenta
Expression of pro-inflammatory mediators is, in turn, hypothesized to result in (i) increases in prostaglandins, which promote uterine contractility; (ii) degradation of the chorioamnion extracellular matrix; and (iii) ripening of the cervix by matrix metalloproteinases and reduced expression of tissue metalloproteinase inhibitors
With the average American eating over 120 pounds of sugar a year, dental caries are a significant source of infection and inflammation. In part, dental health is associated with birth outcomes – poor teeth causes infection and inflammation that may be associated with pre-term delivery.
Complement regulators and inhibitory proteins Complement pathway review
Accessory molecules for Toll-like receptors and their function Toll like receptor review
NOD proteins: regulators of inflammation in health and disease NOD protein review
Defensins in innate immunity Defensins review