STD Awareness: Which STDs Are Resistant to Antibiotics?

pillsYou’ve probably heard of MRSA, which is pronounced “mersa” and stands for methicillin-resistant Staphylococcus aureus — a strain of bacteria that is resistant to methicillin, as well as pretty much every other antibiotic out there. MRSA is an example of evolution by natural selection — what didn’t kill its ancestors made them stronger, spawning a drug-resistant strain.


There are drug-resistant strains of gonorrhea, trichomoniasis, and syphilis.


Evolution is the force behind life’s diversity. Normally, diversity is a good thing — but when it comes to microbes that cause diseases like gonorrhea, trichomoniasis, and syphilis, these organisms’ ability to evolve new defenses against our antimicrobial drugs isn’t good for us.

STDs have plagued us for millennia, but it wasn’t until the 20th century that we finally developed antibiotics, which gave us a powerful tool against many of our most formidable sexually transmitted foes. Suddenly, scourges like gonorrhea and syphilis could be quickly and easily treated with a dose of penicillin.

Problem solved, right? Nope. Enter evolution by natural selection. Continue reading

STD Awareness: Antibiotic-Resistant Syphilis

Treponema pallidum under a microscope. Image: Dr. Edwin P. Ewing, Jr., CDC

The image to your right, with lively yellow splotches against a pale green background, is not a long-lost Jackson Pollack piece, and the dark squiggly lines aren’t strands of paint haphazardly splattered onto a canvas. In fact, those squiggly lines are magnified images of the spiral-shaped bacteria species Treponema pallidum. You might not have heard of T. pallidum, but you’ve probably heard of syphilis, the sexually transmitted disease (STD) that these bacteria cause. While syphilis isn’t as common as other STDs, like chlamydia and HPV, it’s still out there, and occasionally communities experience outbreaks. It’s always best for sexually active people to be screened for STDs and practice safer sex.


The evolution of syphilis strains that are resistant to certain antibiotics underscores the need to use antibiotics properly.


Syphilis can inflict serious long-term damage — in fact, before the introduction of antibiotics, syphilis was the worst STD out there! Known as the Great Pox when it descended upon Europe 500 years ago, it could cause large and painful boils. Eventually, natural selection led to T. pallidum’s evolution into a form with milder symptoms, which benefited the bacteria by enabling its less boil-ridden (and presumably more attractive) human hosts to spread it farther and wider. Nevertheless, the symptoms of syphilis, if present, still include infectious sores, and when the disease goes untreated, it can cause severe, possibly fatal, damage to the nervous system.

Back in the day, there were myriad inadequate “treatments” for syphilis, ranging from straight-up quackery to the use of partially effective but toxic chemicals such as mercury. But a century ago, in 1912, a new arsenic-based chemical called Neosalvarsan was hailed as a “magic bullet.” Unfortunately, this treatment took weeks or even more than a year to administer — and had dangerous side effects. Quack treatments continued to flourish, and it wasn’t until the widespread adoption of penicillin in the 1940s that an effective cure with few side effects was available.

But natural selection endures; in fact, by flooding T. pallidum’s habitat with certain antibiotics, we’ve created an environment that favors the organism’s evolution against us. While not as immediately threatening as antibiotic-resistant gonorrhea, syphilis has been quietly evolving resistance to some of the antibiotics we use to treat it. This underscores the importance of using antibiotics correctly and emphasizing safer-sex practices, such as using latex condoms during vaginal or anal intercourse and during oral contact with a penis. Continue reading

STD Awareness: Bacterial Vaginosis and Chancroid

Editor’s Note: Please see our post of November 2, 2015 to learn if bacterial vaginosis (BV) can cause sores, and to get the scoop on whether or not it’s actually an STD.

Sexually transmitted diseases can be caused by viruses, bacteria, protozoans, and even animals. Bacterial vaginosis and chancroid are both infections caused by bacteria, which means that they can be treated with antibiotics. While bacterial vaginosis only affects people with vaginas, chancroid disproportionately affects people with penises. You can seek diagnosis and treatment for bacterial vaginosis and chancroid at a Planned Parenthood health center, as well as health clinics, private health-care providers, and health departments.

Bacterial vaginosis is caused by an imbalance of bacteria species in the vagina. Image: renjith krishnan / FreeDigitalPhotos.net

Bacterial vaginosis is caused by an imbalance of bacteria species in the vagina. Image: renjith krishnan / FreeDigitalPhotos.net

Bacterial Vaginosis
Bacterial vaginosis seems to be most commonly caused by the bacteria species Gardnerella vaginalis. Scientists aren’t quite sure how this infection is caused, but risk seems to correlate with a change in sexual partners, having multiple sexual partners, douching, or using an intrauterine device; it can also occur in females who have never been sexually active. It is more common in pregnant women. There is no counterpart to this infection in males, although G. vaginalis can be found in their urethras; this raises the possibility that bacterial vaginosis can be sexually transmitted, in which case it could be directly transmitted between two females or indirectly transmitted from one female to another via a male.

Bacterial vaginosis seems to result from an imbalance in the vaginal flora (“flora” is a somewhat fanciful term for the bacteria that live in your body; under normal circumstances they are harmless and even beneficial). Vaginas usually are habitat to a population of bacteria called Lactobacillus, which produce hydrogen peroxide as a byproduct. When the number of Lactobacillus declines, G. vaginalis is able to move in on Lactobacillus’ old territory. The decrease in Lactobacillus and increase in G. vaginalis leads to a rise in the vagina’s pH. The new vaginal environment is less acidic and more alkaline; a vaginal pH of more than 4.5 is one criterion for the diagnosis of bacterial vaginosis. Another symptom includes a vaginal discharge that may smell somewhat fishy. There might also be genital itching or pain during urination. It is also possible not to have symptoms. Continue reading