STD Awareness: The Surprising Sexual Transmission of Non-STDs

What is a sexually transmitted disease, or STD? If someone catches their partner’s cold during sex, is that cold an STD? According to the Office on Women’s Health, an STD is “an infection passed from one person to another person through sexual contact.” Unless the cold was passed through sexual contact, rather than mouth-to-mouth contact, it would not be considered an STD. Others say that, for an infection to be considered an STD, its sexual transmission must make it significantly more common in the population. So, a disease like the common cold would probably be just as common even if people never had sex.


MRSA, meningitis, and the virus that causes pinkeye can be transmitted sexually.


However, there are some infections, such as hepatitis C or bacterial vaginosis, whose status as official STDs is controversial. While researchers argue with one another over where to draw the line between an STD and a non-STD, let’s take a look at some bacteria and viruses that can be transmitted sexually, even though they’re not officially categorized as “STDs.”

MRSA: Methicillin-Resistant Staphylococcus aureus

MRSA bursting out of a dead blood cell. Image: Frank DeLeo, NIAID

MRSA bursting out of a dead blood cell. Image: Frank DeLeo, NIAID

You’ve probably heard of MRSA, which is pronounced “mersa” and stands for methicillin-resistant Staphylococcus aureus — a strain of bacteria that is resistant to every antibiotic in the penicillin family, as well as others. S. aureus, or “staph” for short, is the same bacteria responsible for TSS, or toxic shock syndrome, which has most infamously been associated with the use of highly absorbent tampons. But mostly, staph is a common cause of skin infections, which could be deadly in the pre-antibiotic era, but these days usually don’t raise too many eyebrows.

Unfortunately, with the emergence of MRSA, which is difficult to treat with the usual drugs, we might once again have to worry about minor skin infections blossoming into life-threatening conditions. Additionally, MRSA has found a way to hop from person to person via sexual contact, and sexually transmitted MRSA has been documented in both heterosexual and MSM (men who have sex with men) populations. Untreated, it can lead to a form of gangrene in which tissue blackens as it dies. Continue reading

STD Awareness: Mycoplasma genitalium

“I’m not small, I’m just streamlined!” Image of Mycoplasma genitalium adapted from American Society for Microbiology.

In November and December of last year, headlines touting a “new” STD made an ever-so-minor flurry across the Internet. CNN referred to it as “mycoplasma genitalium, or MG” — Mycoplasma genitalium is the name of the teardrop-shaped bacteria that can cause several diseases in the urinary or reproductive tracts, such as urethritis and pelvic inflammatory disease.

M. genitalium is the smallest living organism known to science, having “devolved” from more complex organisms — but that doesn’t mean it can’t pack a punch! While these bacteria have surely been around for millennia, we only discovered them in the 1980s. Since then, we’ve known that M. genitalium fits the profile of a sexually transmitted pathogen — the only reason it made the news last year was that a team of British researchers published further evidence that this bug is indeed sexually transmitted and capable of causing disease.


Genital mycoplasmas can be cured — but a doctor needs to know what she’s looking for in order to prescribe the correct antibiotic!


An infection with M. genitalium could more generally be called a “genital mycoplasma.” The term “genital mycoplasmas” refers to a category of several different species of sexually transmitted bacteria, most notably Mycoplasma genitalium, but also less common species, such as Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum. M. genitalium is considered an “emerging pathogen,” because it is only over the past couple of decades that technology has allowed us to study these bacteria, along with other genital mycoplasmas.

Risk factors for infection include multiple sexual partners and not using condoms during sex. It is thought that most people with an M. genitalium infection don’t have immediate symptoms — 94 percent of infected men and 56 percent of infected women won’t notice anything amiss. That doesn’t mean it can’t do damage. Continue reading

STD Awareness: 10 Sexually Transmitted Diseases You Probably Don’t Know About

Giardia lamblia, a microbe that can be transmitted sexually. Image: NIH

Gonorrhea and chlamydia go back to antiquity. Syphilis took hold in Europe during the late 15th century. Herpes wasn’t on most people’s radars until the early 1980s, and human papillomavirus (HPV) was relegated to relative obscurity in the popular imagination until the HPV vaccines made their debuts less than a decade ago.


Have you heard of CMV, chancroid, or donovanosis?


But there are still a handful of sexually transmitted diseases (STDs) that you might not know about. These include incredibly common infections, as well as those caused by pathogens you might have heard of but probably don’t associate with sexual transmission. They also include infections that are very rare here in Arizona but are much more common in other parts of the world. They all deserve a closer look.

10 Trichomoniasis: What is the most common curable STD? You might guess that it’s chlamydia or gonorrhea, but according to the Centers for Disease Control and Prevention, it’s trichomoniasis (also known as trich, pronounced “trick”). This infection is caused by Trichomonas vaginalis, a single-celled parasite that is actually pretty cute as far as microbes go. What’s not so cute is its propensity to attach to your cells and degrade their surfaces, which on a large scale can produce unpleasant symptoms. Continue reading