Tag Archives: lactobacilli

STD Awareness: The Vaginal Microbiome and Cervical Cancer

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Cervical cancer is caused by human papillomavirus (HPV), which has been nicknamed “the common cold of STDs” — because pretty much every sexually active person will get it at some point. Luckily, that scary stat is poised to change as more people receive the HPV vaccination, which protects against nine major strains of the virus.

HPV jumps easily from person to person, spread by pretty much all types of sexual contact. For most people, the infection clears up within 8 to 13 months, but sometimes the infection develops into a chronic condition, which increases risk for certain cancers — including cervical cancer, but also cancers of the anus, genitals, and throat. Unfortunately, it’s hard to predict if your immune system will vanquish your infection, or if you’ll develop a chronic infection.

Members of the lactobacilli family, keeping vaginas healthy across the globe. Image: Josef Reischig

Luckily, the vagina has some tricks up its sleeve to protect itself from HPV, and some of its best weapons are bacteria. Yep — a healthy vagina isn’t germ-free. To the contrary, it needs lactobacilli and other beneficial microbes to maintain a healthy environment. Bacteria from the Lactobacillus genus produce lactic acid and other chemicals, which help keep dangerous bugs away. Vaginal environments in which Lactobacillus gasseri dominate, for example, are more likely to clear HPV infections. L. crispatus helps trap HIV in a thick mucus, reducing infection risk. Other lactobacilli species secrete chemicals that ward off yeast infections. Sometimes, however, good bacteria lose this turf war, and “bad guys” move in.

The population of microbes that live in your vagina are known collectively as the vaginal microbiome.

University of Arizona researchers in Phoenix performed a “census” of the vaginal microbial communities of 100 premenopausal women. They learned that women who have cervical cancer or precancerous abnormalities have drastically different vaginal microbiomes. Healthy vaginas were generally dominated by lactobacilli, but as cervical health declined, their populations declined, and “bad” bacteria took over. One such bad guy, called Sneathia, was linked to HPV infection, precancer, and cervical cancer.

Which Came First?

Finding a new vaginal “bad guy” was exciting, and Sneathia had previously been linked to other gynecological problems, ranging from bacterial vaginosis to pregnancy complications. But the researchers were looking at a snapshot in time — they didn’t know what came first, the Sneathia or the cervical abnormalities. Were lactobacilli protecting the cervix whereas Sneathia were harming it, or did a chronic HPV infection set the stage for Sneathia to move in and thrive? It’s a real “chicken-and-egg” conundrum. Continue reading →

STD Awareness: Trichomoniasis, the Pear-Shaped, Blood-Sucking, Silent Scourge

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What’s shaped like a pear, hangs with a posse of bacteria, and is a silent scourge upon millions of urogenital tracts? I hope you guessed Trichomonas vaginalis, the single-celled parasite that causes trichomoniasis, or trich (pronounced “trick”). Trich is the most common curable sexually transmitted disease out there — currently afflicting around 3.7 million Americans and 156 million Earthlings.

These single-celled creatures pack a punch, but the body fights back.

When trich causes symptoms, sufferers might experience vaginal discharge (which sometimes has a bad odor), penile burning or discharge, spotting, and itching or swelling in the genital area. But around 70 percent of infections have no symptoms at all, making it a mostly “silent” disease. Based on the totality of the evidence, the Centers for Disease Control and Prevention (CDC) doesn’t currently recommend routine screening for trich in people without symptoms.

But it’s the subject of some debate. Since both symptoms and screenings are rare, and the disease isn’t reportable, some health experts worry that trich could be doing a lot of damage right under our noses. An infection during pregnancy could increase risk for preterm labor or low birth weight. It can increase risk for both acquiring and transmitting HIV from or to a partner. Women with trich are more likely to acquire an HIV infection when sexually exposed to the virus — in fact, one study estimated that 6.2 percent of all HIV infections among U.S. women could be attributed to trich. It’s also easier to catch HIV from a man with trich than from a man without trich. Continue reading →

STD Awareness: Is Bacterial Vaginosis a Sexually Transmitted Disease?

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Not to scale: Gardnerella vaginalis under a microscope. Image: K.K. Jefferson/Virginia Commonwealth University

Gardnerella vaginalis under a microscope. Image: K.K. Jefferson/Virginia Commonwealth University

Bacterial vaginosis, or BV, is the most common vaginal infection among people 15 to 44 years of age. It’s caused by an overgrowth of harmful bacteria, such as Gardnerella vaginalis. A healthy vagina hosts thriving populations of Lactobacillus bacteria species, but when these “good” bacteria are crowded out by certain types of “bad” bacteria, the vaginal ecosystem can be shifted, causing BV.

There is a lot of confusion about BV. Is it a sexually transmitted disease (STD)? What are the symptoms? How can you avoid it?

All good questions. Let’s examine them one by one.

Is BV an STD?

The consensus seems to be that BV isn’t officially an STD, but even reliable sources have somewhat contradictory information. Planned Parenthood doesn’t list BV as an STD on their informational webpages. The Centers for Disease Control and Prevention (CDC) does include BV on their STD website, but also says that “BV is not considered an STD.”

On the other hand, the Office on Women’s Health says that “BV can … be caused by vaginal, oral, or anal sex” and that “you can get BV from male or female partners.” And there’s an entire chapter devoted to BV in the premier medical textbook on STDs, and its authors say that, while sexually inexperienced females can get BV, “the weight of evidence supports sexual transmission” of G. vaginalis, the bacteria species most famously implicated in BV infections.

The same webpage on which the CDC declared BV not to be an STD also says that it can be transferred between female sexual partners. Indeed, women who have sex with women have higher rates of BV. Since vaginal fluid could spread BV, partners can change condoms when a sex toy is passed from one to another, and use barriers like dental dams when engaging in cunnilingus (oral contact with the female genitalia) or rimming (oral contact with the anus).

What about heterosexual transmission? Continue reading →

Is Douching Safe?

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This vintage douche ad claims that its product is “safe to delicate tissues” and “non-poisonous.”

Douching is the practice of squirting a liquid, called a douche, into the vagina. Many people believe it helps keep the vagina clean and odor-free, and some are under the impression that it helps prevent pregnancy and sexually transmitted diseases. An estimated 25 percent of American women 15 to 44 years old douche regularly. But just because douching is widespread doesn’t mean it’s safe; indeed, there are two possible mechanisms by which douching might be harmful.

First, douching might alter the pH of the vagina, changing its ecosystem. You might not think of a vagina as an “ecosystem,” but the bacteria and other microscopic organisms that live there sure do — and altering their habitat can harm the beneficial microbes that live there, opening the door for disease-causing microbes to take over the territory. Frequent douching can result in the vagina’s normal microbial population having difficulty reestablishing its population.

Douching increases risk for infections and fertility problems, and has no proven medical benefits.

Second, a douche’s upward flow might give pathogens a “free ride” into the depths of the reproductive tract, granting them access to areas that might have been difficult for them to reach otherwise. In this manner, an infection might spread from the lower reproductive tract to the upper reproductive tract. Douching might be an even bigger risk for female adolescents, whose reproductive anatomy is not fully formed, leaving them more vulnerable to pathogens.

While douching is not guaranteed to harm you, there is no evidence that it is beneficial in any way. Establishing causation between douching and the problems that are associated with it is trickier — does douching cause these problems, or do people who douche also tend to engage in other behaviors that increase risk? So far, the best evidence indicates that douching is correlated with a number of diseases and other problems, including sexually transmitted diseases (STDs), bacterial vaginosis, pelvic inflammatory disease, fertility and pregnancy complications, and more. Continue reading →

Does Douching Work?

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illustration of a douching apparatus from an 1882 medical handbook

As a newly minted teenager, I was helping my mother go through some of my recently deceased great-grandmother’s things. I held a mysterious object in my hands and studied it curiously, puzzling over its unfamiliar form, pastel color scheme, and floral pattern. Finally, I gave up: “What is this?” I exclaimed. My mom, instantly uncomfortable, muttered her answer through clenched teeth: “It’s a douche bag,” she replied.

I remember being rather scandalized, but also a bit amused to be holding a piece of ancient misogynist history in my hands. Even as a junior high student, I knew that douching was marketed toward women with the message that their vaginas were “dirty” and in need of “cleansing” — scientifically invalidated ideas to which we surely no longer adhered. It seemed fitting that we were sorting through the belongings of a person born in the 19th century, dividing them into the useful and useless. Surely the douche bag belonged in the latter category.

Just because douching products are available in drugstores doesn’t mean they’re safe or effective.

Little did I know, more than 20 years ago, that douching hasn’t exactly been relegated to a historical footnote. Overall, nearly 25 percent of American women 15 to 44 years old douche regularly — which is down from nearly a third in 2002. Douching rates may vary by ethnic group: CDC data from 2005 found that 59 percent of non-Hispanic black women, 36 percent of Latinas, and 27 percent of white women douche. Socioeconomic status and education level can also be a factor.

For those of you who don’t know, vaginal douching is the practice of flushing the vagina with a liquid, which is administered through a nozzle that is inserted into the vagina. Some people believe that douching cleanses or deodorizes the vagina, or can prevent pregnancy or infections. Some might think their partners expect them to douche, or that douching will “tighten” or “rejuvenate” their vaginas.  Continue reading →