A Microbial Mission Below the Belt

The bug-busting potential of the vaginal microbiome.

A word of warning for those with a delicate disposition.

Frankly, this week’s newsletter contains more organs than a Wurlitzer showroom.

And, in particular, we’re focusing on what you might term, ahem, “below the belt” body parts.

Yup, vaginas specifically, although let’s not entirely leave penises out.

Roughly speaking, the worldwide ratio of penises to vaginas is 101 to 100.

Since just about half the world’s population have vaginas, we figured it was high time for us to focus our weekly newsletter on the part of the anatomy that was named in the 17th century after the Latin word for “sheath” or “scabbard.”

The vagina – the muscular canal that connects the uterus to the vulva – is one of five human microbiome sites that you can sample using our Five Site Explorer™ Kit, so we’re unsurprisingly greatly interested in the vaginal microbiome.

Pay a visit to the “women’s products” aisle in a pharmacy, and you could easily conclude that bacteria and other microbes are a bad thing to carry around in a vagina.

However, the truth is that a vagina’s carefully balanced microorganisms play a crucial part in overall health.

For the longest time, experts viewed the microbial community of the vagina as being overwhelmingly made up of Lactobacillus bacteria.

This genus is characterized by its ability to ferment carbohydrates to form lactic acid. The result of this is the establishment of somewhat acidic conditions in the vagina, which are toxic to many pathogenic microbes.

Something like 10,000 years ago, humans started to make and eat foods such as cheese and yogurt, after fermenting milk.

These products contain large amounts of Lactobacillus bacteria, leading some scientists to hypothesize that this is when vaginas may have acquired these microorganisms, as microbes in feces found their way from one part of the body to another.

Vaginas are ideal spots for Lactobacillus to thrive, since they contain low levels of oxygen, and – during a female’s reproductive years – have plentiful amounts of the sugars that keep Lactobacillus well-fed.

The balance of microbes in the vagina is a delicate one, and it can be easily disturbed by normal occurrences such as intercourse or menstruation.

Semen, for example, can lower the vagina’s acidity – and along with menstruation this can lead to a reduction in Lactobacillus levels, enabling other microorganisms to thrive, including those that may be associated with bacterial vaginosis (BV).

BV is an incredibly common condition characterized by an odorous vaginal discharge. It’s sometimes treated with antibiotics.

Now, as someone with a vagina, you may have viewed it as having a number of purposes, but it’s probably a reasonably safe bet that you’ve never thought of it as an antibiotics factory.

We’re about to change that, though, by checking out the extraordinary work of a team of scientists from UCSF, led by microbiologist and chemist Michael Fischbach.

Effectively, they’ve developed a potentially powerful antibiotic, made by bacteria that live in the vagina.

Lactocillin (there’s that “lacto” again) is what’s known as a Thiopeptide, a class of antibiotics produced by bacteria, many members of which show promise against that vile wicked witch of the north, MRSA (methycillin-resistant Staphylococcus aureus).

Fischbach’s team used a cool methodology into which they built a machine learning algorithm, then trained a computer program to recognize genes they already knew could generate molecules with the capacity to act as drugs.

When they used this process to search for similar genes in the human microbiome, they were staggered to find literally thousands of them within microbes living in and on the human body.

One of these, found in the vaginal microbiome, was Lactobacillus gasser, which was purified, synthesized, and used as the foundation for the new antibiotic.

As Fischbach commented, “Bacteria that live on and inside us are actually making drugs right on [our bodies].”

Finally, let’s end with a brief nod back to the 17th-century roots of the word “vagina.”

Curiously, there’s another noun that shares exactly the same etymology.


Just something to ponder when you’re choosing between the tubs of Ben & Jerry’s this weekend.

More reading

A Systematic Analysis of Biosynthetic Gene Clusters in the Human Microbiome Reveals a Common Family of Antibiotics

Drugs from where?! Female genitals may be source of uniquely effective antibiotic

The Superhero in the Vagina

Vaginal microbe yields novel antibiotic