Tag Archives: mosaic gene

STD Awareness: Is Mouthwash a Match for Gonorrhea’s Superpowers?

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Since the 1930s, we’ve enjoyed around eight decades of easily cured gonorrhea — at least in places with easy access to antibiotics — but experts fear those days are numbered. In the past year or so, cases of untreatable gonorrhea have occasionally made headlines.

Thanks to the powers of evolution, some bacteria have acquired the multiple genes necessary to withstand the onslaught of the pills and shots administered by doctors. Gonococci, the bacteria that cause gonorrhea, are starting to win this “arms race” with humans, whose antibiotic arsenals are losing effectiveness. And with gonorrhea on the rise, gonococci may be evolving at an ever-quickening clip.

In 1879, Listerine claimed to cure gonorrhea. Today, scientists are finally testing that claim. We await the results.

Oral Gonorrhea: The Silent Scourge

Many experts believe oral gonorrhea is a key driver of antibiotic resistance. These infections usually don’t cause symptoms, and without symptoms people usually don’t seek treatment. Without treatment, gonococci can hang out in a throat for up to three months.

After transmission by oral sex — and possibly even by kissing  — gonococci can set up camp in the throat, which is an ideal environment for acquiring antibiotic resistance. They might not be causing symptoms, but they’re not sitting there twiddling their thumbs, either. If there’s one thing gonococci love to do, it’s collecting genes like some of us collect trading cards, and the throat is a gathering place for closely related bacteria species that hand out antibiotic-resistance genes for their expanding collections.

Gonococci can easily scavenge DNA from their surroundings — say, from a dead bacterium — and patch long segments of these genes into their own DNA, creating genetic hybrids between themselves and other organisms. Last month, scientists from Indiana University caught this phenomenon on video for the first time.

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STD Awareness: Genetics and the Gonococcus

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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 →