STD Awareness: Gonorrhea’s Ever-Growing Resistance to Antibiotics

gonococci

Gonococci, the bacteria that cause gonorrhea.

Ever since the advent of effective antibacterial therapies less than a century ago, humans with access to these drugs can easily cure gonorrhea. 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 — sulfa drugs and antibiotics not only erased these infections from our bodies, they also erased memories of gonorrhea’s dangers from our collective consciousness.


There are two drugs remaining to treat gonorrhea, and resistance to them is climbing higher as the years march on.


Unfortunately, thanks to their talent for genetic gymnastics, gonococci, the bacteria that cause gonorrhea, have been evolving resistance to every drug we’ve thrown at them — to tetracycline, to penicillin, and more recently to fluoroquinolones. One class of antibiotics remains to treat gonorrhea: cephalosporins. In 2013, Centers for Disease Control and Prevention (CDC) Director Tom Frieden warned that we could find ourselves in a “post-antibiotic era” – unless we take precautions. And, just two weeks ago, the latest study from the CDC’s Gonococcal Isolate Surveillance Project sounded the alarm that the post-antibiotic era is drawing ever closer, especially when it comes to gonorrhea.

Azithromycin and ceftriaxone, the two drugs that are used in combination to deliver a one-two punch to invading gonococci, are the best antibiotics remaining in our arsenal. Azithromycin is taken by mouth, while ceftriaxone is administered by a shot, and when taken together they team up to target different weak points in gonococci’s armor. Azithromycin interferes with the bacteria’s ability to make proteins, shutting the cells down, while ceftriaxone causes the cell wall to fall apart. However, the gonococci can acquire resistance. For example, in the case of azithromycin, a resistant bacterium can spit out the drug before it has a chance to kill it, or it can change the shape of its protein-making apparatus such that the drug can’t attach to it.  Continue reading

STD Awareness: Genetics and the Gonococcus

Illustration: CDC

Illustration: 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: 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

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