STD Awareness: The Curious Case of Chancroid

Haemophilus ducreyi arrange themselves in parallel rows, which researchers have called “railroad tracks,” “schools of fish,” and “fingerprints.” Image: Mike Miller, CDC

Earlier this year, I asked a room full of scientists and medical professionals to raise their hands if they’d ever heard of chancroid. Everyone sat there, motionless, confused by the odd syllables I had uttered — shan kroyd. If you’ve never heard of chancroid, you’re not alone.

Chancroid is a sexually transmitted disease (STD) brought to you by Haemophilus ducreyi, a type of bacteria that can pass through microscopic tears in the skin during sexual contact. When one partner is infected, there is a 1 in 3 chance the other will become infected. An infection can cause painful sores and swollen lymph nodes, most often in the genital region. About half of people with chancroid infections will experience “buboes,” or swollen lymph glands that might rupture. Before it could be cured with antibiotics, a persistent infection could cause permanent skin damage.


Humanity can make chancroid the first STD to go extinct.


One reason you probably haven’t heard of chancroid is that, in the developed world at least, it has mostly disappeared. In fact, researchers believe chancroid can be completely wiped off the planet — which would make it the first STD ever to be forced into extinction. How amazing would that be?

Chancroid has been hopping from loin to loin since at least the days of the ancient Greeks, and was common until the 20th century, when rates began to decline. Thanks to antibiotics, U.S. chancroid rates decreased 80-fold between 1947 and 1997, all but vanishing by the late 1950s. It was virtually unheard of until there was another spike in the 1980s, correlating with the crack epidemic. But, since 1987, cases have been steadily declining. Continue reading

STD Awareness: Genetics and the Gonococcus

Image: CDC

Ever since the discovery of effective antibacterial therapies less than a century ago, humans have been able to easily cure gonorrhea, the sexually transmitted scourge that laid waste to fallopian tubes and robbed newborns of vision. Most of us in the developed world have forgotten that this disease was once a leading cause of infertility in women and blindness in babies — and still is in much of the developing world.

Unfortunately, gonococci — the species of bacteria that cause gonorrhea — have been evolving resistance to every antibiotic we’ve thrown at them, including sulfonamides, penicillins, tetracyclines, macrolides, fluoroquinolones, and narrow-spectrum cephalosporins. We have one remaining first-line gonorrhea treatment left: extended-spectrum cephalosporins, which include cefixime, which is taken orally, and ceftriaxone, which is administered as a shot — and resistance is emerging to those drugs, as well.


Gonococci don’t swap potato salad recipes at family reunions — they swap genetic material!


The emergence of antibiotic-resistant gonorrhea is considered one of the most pressing problems in infectious disease — just two years ago, the Centers for Disease Control and Prevention named it an “urgent threat,” and indeed, gonorrhea seems to be evolving resistance to drugs at quite a rapid clip. Gonococci can acquire resistance to antibiotics in three ways.

First, a genetic mutation can endow bacteria with special antibiotic-fighting powers, making it harder for a drug like penicillin to attach to their cells and destroy them. Such a mutant is more likely to gain evolutionary traction if it finds itself in an antibiotic-drenched environment in which resistance to that drug allows it to “outcompete” other bacteria. Indeed, antibiotic resistance was first documented in the 1940s, just years after sulfonamides and penicillin were introduced as the first effective cures for gonorrhea. Continue reading

STD Awareness: Gonorrhea, Women, and the Pre-Antibiotic Era

Penicillin, the first cure for gonorrhea, was developed for mass production in the 1940s.

Penicillin, the first reliable cure for gonorrhea, was mass produced in the 1940s.

It’s Women’s History Month, a time to reflect on the achievements of women worldwide — like Margaret Sanger, Rosalind Franklin, and Florence Nightingale, or contemporary heroes like Wangari Maathai. But it may also be a time to examine some of the sadder aspects of womanhood, including the increased burden gonorrhea imposes on women. While gonorrhea is no picnic for anyone, it wreaks the most havoc in female reproductive tracts. In fact, before antibiotics, gonorrhea was a leading cause of infertility — one 19th century physician attributed 90 percent of female infertility to gonorrhea. Not only that, but the effects of gonorrhea could seriously reduce a woman’s overall quality of life.


With gonorrhea becoming more resistant to antibiotics, the CDC warns of a return to the pre-antibiotic era.


Gonorrhea is described by written records dating back hundreds of years B.C. Ancient Greeks treated it with cold baths, massage, “cooling” foods, and vinegar. In the Middle Ages, Persians might have recommended sleeping in a cool bed with a metal plate over the groin. A bit to the west, Arabs tried to cure gonorrhea with injections of vinegar into the urethra. Kings of medieval England might have had their gonorrhea treated with injections of breast milk, almond milk, sugar, and violet oil.

Although gonorrhea is as ancient an STD as they come, because women rarely have symptoms while men usually do, for much of history it was mostly discussed in terms of men. The name gonorrhea itself derives from the ancient Greek words for “seed flow” — gonorrhea was thought to be characterized by the leakage of semen from the penis. This confusion inspired many misguided notions throughout the millennia, such as the idea that almost all women carried gonorrhea and transmitted it to their unwitting male partners. Continue reading

STD Awareness: An Update on Antibiotic-Resistant Gonorrhea

Last year, we shared the fascinating and frightening story of the emergence of increasingly antibiotic-resistant gonorrhea, an STD caused by the gonococci bacteria. The sexually transmitted scourge, which we only so recently reined in with the development of antibiotics, has been performing some genetic gymnastics to defeat almost every drug we’ve thrown at it. We douse it with certain drugs, and the bacterium literally spits them back out at us, and it inactivates other drugs by snapping the active molecules in half. Sulfa drugs, penicillins, tetracyclines, fluoroquinolones — they all make a gonococcus heave a bored sigh. Luckily, cephalosporins were still an effective treatment, but recently there have been reports of stubborn gonorrhea infections caused by the latest and greatest (and some might say most hated) strain of gonococci.


The bacteria that cause gonorrhea continue to evolve, right under our noses!


Well, the story isn’t over — just like the bacteria that cause gonorrhea, the tale is rapidly evolving. The latest class of antibiotics that the gonococci are chipping away at is the cephalosporin family, which includes several chemically related drugs that work in similar ways — and that can likewise be defeated by microbes in similar ways. Cephalosporin-resistant gonorrhea was first reported in Japan and documented in a few European countries. The Japanese case that inspired the New England Journal of Medicine to declare last year that it was “time to sound the alarm” was an oral gonorrhea infection that was resistant to one member of the cephalosporin family: ceftriaxone.

Earlier this month, the prestigious medical journal JAMA reported the first North American sightings of gonorrhea that failed treatment with another cephalosporin: cefixime. Yeah, I know, you’d rather hear about Big Foot or UFO sightings, not evidence that something as real and unmythical as Gonorrhea 5.0 has landed in your back yard. Luckily, there’s plenty you can do to protect yourself from it, and we’ll tell you all about it toward the end of this article. (Spoiler alert: It involves using condoms!) Continue reading

STD Awareness: Antibiotic-Resistant Gonorrhea

Under the microscope, Neisseria gonorrhoeae infects larger human cells (click to enlarge). The bacteria resemble tiny pairs of coffee beans. Image: Dr. Norman Jacobs, CDC

Writing about sexually transmitted diseases (STDs), one must walk the line between warning readers of risks and engaging in full-fledged alarmism. So it’s a bit disconcerting that researchers writing in the New England Journal of Medicine last month declared that it’s “time to sound the alarm”: The emergence of completely antibiotic-resistant gonorrhea is becoming more of a realistic threat and less of a theoretical possibility. The bacteria that cause gonorrhea are evolving faster than we can develop effective antibiotics against them, and a return to the era of untreatable gonorrhea could see a rise in the particularly nasty complications that arise from a long-term gonorrheal infection, such as pelvic inflammatory disease and epididymitis.


There are genes that confer resistance to every single antibiotic we use to cure gonorrhea. If they all combine within one organism, we might have a superbug on our hands.


Neisseria gonorrhoeae is a species of tricky bacteria that cause gonorrhea, which can infect the mouth, throat, rectum, urethra, cervix, and even eyes. These bacteria have vexed us for thousands of years, having evolved many strategies for entrenching themselves in our bodies. They can alter the proteins that adorn their surfaces, rendering our immune systems incapable of recognizing them. They can form colonies in which they work together to manipulate our cell surfaces with their retracting appendages until they’re allowed entry inside, where they can surreptitiously multiply.

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

Why are we talking about MRSA in a post about STDs? It’s not just because MRSA has apparently found a way to be transmitted sexually, but also because it helps make the concept of antibiotic-resistant gonorrhea more accessible. It wasn’t until less than a century ago that we finally developed a magic-bullet treatment for gonorrhea, and for a handful of decades it was quickly and easily treated with a dose of penicillin. Enter evolution by natural selection. Continue reading

STD Awareness: Gonorrhea

Neisseria gonorrhoeae, which causes gonorrhea, is pictured here in a photograph taken with a scanning electron microscope. Projecting from the organism’s surface are many pili, powerful appendages that enable the bacteria to adhere to human cells. Image: National Institute of Biomedical Imaging and Bioengineering.

April is STD Awareness Month, but this blog has sought to increase your awareness of sexually transmitted diseases on a monthly basis. So far in 2011 we’ve pointed the spotlight at human papillomavirus, barrier methods, and herpes. This month’s installment will focus on gonorrhea, colloquially known as “the clap,” a common sexually transmitted disease caused by sneaky bacteria called Neisseria gonorrhoeae. It is spread by vaginal, anal, and oral sex, and can infect certain cells in the throat, mouth, rectum, urethra, or cervix. It can also be transmitted manually to infect the eye. If you are sexually active, you can reduce risk of transmission by consistently and correctly using latex barriers such as condoms and dental dams.

Four out of five females infected with gonorrhea do not experience symptoms – males, however, usually do, but they can be mild and therefore easy to overlook. Symptoms can appear within a month, and might include painful or frequent urination, vaginal or penile discharge, painful bowel movements, itching, or sore throat. Additionally, females can experience abdominal pain, fever, irregular menstruation, or bleeding between periods. In pregnant women, untreated gonorrhea infections can lead to complications such as premature labor or stillbirth. The infection can also be passed from mother to infant during delivery.  Continue reading