‘Microbiome' is a hot word right now. But what does it mean? It’s the bacteria, fungi, protozoa and viruses that live within us and also on us. These microbes contain genetic material and a single human body has over 100 trillion microbes. (1)

And why do we care about the microbiome? The way these microbes interact with our bodies has great implications for gut health, vaginal health, oral health, skin health, autoimmune disorders, metabolic dysfunction (ie. obesity) and prenatal care (… honestly, the list goes on and on). 

The evidence is mounting to support the idea that we inherit a huge part of our microbiota from our mother (although, we don’t study the inheritance from fathers nearly as much). (2) We could go into this entire topic itself, but for now I’m going to stick to the vaginal microbiome.

The growth and changes of the microbiota in the vagina are dynamic. They change over the entire female reproductive life cycle, and can also vary over a given menstrual cycle (due to fluctuations in estrogen levels). Pregnancy and breastfeeding create major changes in the vaginal microbiome, but also in the gut microbiome (alas, we’ll save the gut microbiome for another day). Naturally, it has also been identified that the postmenopausal vaginal microbiota has significant differences from the microbiota that is present during a female’s reproductive period. (3)

Now, the vaginal flora of most healthy women is dominated by one or more of the Lactobacillus species. (4) The Lactobacilli produce hydrogen peroxide and lactic acid, creating an acidic vaginal environment. It’s been suggested that when Lactobacilli dominate (and have higher amounts of lactic acid), there is greater protection against infections. (5,6) A normal vaginal pH usually ranges between 3.5-4.5 (some sources argue it’s more like 3.8-4.5). (7) If the Lactobacilli population directly affects the pH of the vagina, it’s important to consider vaginal flora when thinking about pH values of vaginal infections. When the vagina is dominated by beneficial Lactobacilli, this is considered ‘vaginal eubiosis.’ When there is overgrowth of other, less desirable bacteria, this is termed as ‘vaginal dysbiosis.’ (8)

Now, let’s get real - how many women end up having some type of vaginitis or abnormal discharge at some point in their life? And sometimes discharge gets funky for a few days and then resolves itself - that can definitely happen. And the amount of discharge you produce throughout the menstrual cycle changes - that’s normal, and can provide insight as to when you’re fertile. But fertility awareness methods (FAM) are a whole other topic for another time. 

Let’s talk about three common (and one not so common) causes of vaginal infection. Note that these can happen at any point, both pre- and post-pregnancy, pre- or post-menopausal.

1. The common yeast infection is caused by the Candida species (typically Candida albicans). The most prominent thing about yeast infections is the itching and irritation. The discharge is usually white with a curdy, thick appearance. That being said, you really could have a yeast infection without any actual discharge - the primary concern could just be significant itching. The pH is usually under 4.5, which is considered normal.

2. Trichomoniasis vaginalis (a triflagellated protozoan). In my own clinical experience, this is not as common as other vaginal infections. This typically presents with odour, irritation and profuse (white, green or yellow) discharge that tends to be watery, frothy or even foamy. The discharge and irritation may be most severe just before and immediately after a menstrual period. (9) The pH is typically high (over 5.0, often ranging from 5.0-7.0).

3. Bacterial vaginosis (also just known as BV). Now, this is caused by depletion of that Lactobacilli species we are always talking about. A depletion of Lactobacilli also causes a direct reduction in hydrogen peroxide and lactic acid. This allows overgrowth of other (not so desirable) bacteria, Gardnerella vaginalis being a common culprit. The most prominent thing about BV is the fishy/ammonia odour. The discharge is usually moderate-profuse, with a homogenous, white-grey appearance. Now the pH is higher again, usually over 4.5, due to the loss of the Lactobacilli - causing a more basic pH. (8)

4. Cytolytic vaginosis (also known as Doderlein’s cytolysis) - sort of the opposite problem of BV - it’s an overgrowth of Lactobacilli. This condition is often overlooked or misdiagnosed as a yeast infection (and won’t respond to antifungals the way a yeast infection would). We discussed Lactobacilli already, so you’ll connect the dots and see that this overgrowth will cause even greater acidity and hydrogen peroxide, causing irritation to the vaginal mucosa. This condition causes irritation and could have a thick, white discharge (although, sometimes discharge isn’t present at all). The pH is usually below 4.5. Since the vaginal mucosa becomes quite acidic, these patients usually feel better with their menstrual flow, as the menstrual flow itself tends to be more basic, providing relief to the acidity of the vagina. This condition is ONLY diagnosed as a ‘diagnosis of exclusion,’ meaning that yeast, BV and Trichomoniasis (and any potential STIs: Chlamydia, Gonorrhea) need to be ruled out first. And as you could imagine, if you provide more Lactobacilli (via vaginal probiotics) to these patients, this could worsen their symptoms. 

There is a significant amount of research supporting the use of oral and/or vaginal probiotics to support the vaginal microbiome. The use of probiotics to colonize the vaginal tract can be helpful in maintaining a healthy vaginal flora but also used proactively to prevent and treat infections. (10) And if you’ve had to use an antibiotic to kick that infection, following up with an appropriate probiotic can be helpful in replenishing some of the good flora that was eliminated. All that said, the type of probiotic used is important. If you haven’t already read my probiotic post, read it here. 

Depending on what type of vaginal dysbiosis you’re dealing with, probiotics may be a useful option or adjunct to consider.

Reference(s):

(1) Gala, M. Chung, D. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Cellular Growth and Neoplasia. 2016. Chapter 1, 3-15. E2. 

(2) PMID: 22411464

(3) PMID: 12037079

(4) PMID: 15911771

(5) PMID: 28418713

(6) PMID: 24223212

(7) Nassos, P. Hooper, C. University of California, San Francisco - Department of Laboratory Medicine. Point of Care Testing. Vaginal pH Test. 2009.

(8) PMID: 28435139

(9) Chacko, M. Needham, H. Woods, C. Feigin and Cherry’s Textbook of Pediatric Infectious Disease: Genital Infections. 2019. Chapter 42, 413-435. E4.

(10) PMID: 24170161

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