STD Awareness: Gonorrhea’s Latest Dubious Honor

Wanted: Scientists who can develop novel antibiotics

A few years ago, the Centers for Disease Control and Prevention (CDC) put out a “greatest hits” list of antibiotic-resistant pathogens. More recently, in late February, the World Health Organization (WHO) followed suit with a dirty-dozen list of 12 “superbugs,” which was composed mostly of potentially fatal microbes that are becoming increasingly impervious to the drugs that once easily killed them. These are the bacteria WHO believes represent the greatest microbial threat to human health, and the list was compiled in the hopes of providing direction — and motivation — to pharmaceutical researchers who are desperately needed to develop new antibiotics.


Investing in antibiotic development now will save lives later.


A quick primer on antibiotic resistance: Antibiotics kill living organisms called bacteria, but like all living organisms, bacteria can evolve. Just as giraffes evolve longer and longer necks that allow them to eat more and more leaves, so too do bacteria evolve resistance to antibiotics. For example, a resistant bacterium can evolve the ability to spit out the drug before it has a chance to kill it, or it can evolve structural changes to its cell wall that make it impossible for the drug to attach to it.

One superbug, classified as an “urgent threat” by the CDC and a “high priority” by WHO, stands out from the pack. Unlike the other bacteria in these lists, an untreated infection with this bug isn’t thought to be deadly — but it still wreaks enough havoc to merit special attention from such esteemed bodies as the CDC and WHO. That bug is Neisseria gonorrhoeae, and you have one guess what disease it causes. (If you said gonorrhea, you guessed right.) Continue reading

STD Awareness: Fully Antibiotic-Resistant Gonorrhea Is on the Horizon

shot-in-armWe’ve been anticipating its arrival for years now, but earlier this fall, the Centers for Disease Control and Prevention (CDC) finally made an announcement: Cases of gonorrhea resistant to the last drugs we use to cure it are emerging.

Over the years, gonorrhea has evolved resistance to every drug we’ve thrown at it — sulfonamides, penicillins, tetracyclines, macrolides, fluoroquinolones, and narrow-spectrum cephalosporins. The last line of defense we have is a one-two punch of a pair of antibiotics: azithromycin and ceftriaxone. By using two drugs, we can delay the inevitable evolution of antibiotic resistance by attacking the bacteria in two vulnerable locations, rather than just one, making it more difficult for the bug to mount a defense and pass on its superior survival skills to subsequent generations.


Prevention is paramount: Stop the spread of antibiotic resistance by practicing safer sex!


Unfortunately, we could only stave off the inevitable for so long. At their conference in September, the CDC announced a cluster of gonorrhea infections that are highly resistant to azithromycin, and that fall prey only to high doses of ceftriaxone. As gonorrhea’s tolerance to ceftriaxone increases, the infection will get more and more difficult to cure.

This cluster of drug-resistant cases was identified in Honolulu in April and May of this year, with five infections showing “dramatic” resistance to azithromycin, as well as reduced vulnerability to ceftriaxone. The good news is that these cases were cured with higher-than-usual doses of antibiotics, but the bad news is that dosages can only climb so high before a drug is no longer considered to be an effective treatment. Continue reading

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: 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: Mycoplasma genitalium

Image of Mycoplasma genitalium adapted from American Society for Microbiology.

“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: Ceftriaxone-Resistant Gonorrhea

syringeNestled in the throat of a Japanese woman was a collection of clones that scientists abducted from their temporary habitat and christened H041 — a humdrum moniker for a strain of bacteria that would burn headlines in medical journals. Though the bacteria never caused symptoms in their host, they lingered in her throat from at least January until April of 2009, when a swab finally tested negative. Rather than succumbing to repeated bombardment by an antibiotic called ceftriaxone, the infection probably just went away on its own — as oral gonorrhea infections tend to do.


Resistance to ceftriaxone, our last good gonorrhea drug, has been reported in Japan, Australia, Sweden, France, and Spain.


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.” 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. Resistance to cefixime was first documented in 1999, leaving ceftriaxone as our best remaining option, and the CDC’s first choice for treating gonorrhea. There are no good alternatives to ceftriaxone remaining, which is why reports of ceftriaxone-resistant gonorrhea are so deeply troubling.

What made H041 special was that it was the first extensively drug-resistant strain of Neisseria gonorrhoeae, the bacteria that cause gonorrhea. With an unusually high level of resistance to ceftriaxone — four to eight times higher than the previous record holder — the strain was also resistant to a slew of other antibiotics: penicillin and its relatives, fluoroquinolones, macrolides, tetracycline, trimethoprim-sulfamethoxazole, chloramphenicol, nitrofurantoin, cefpodoxime, cefixime, ciprofloxacin, and levofloxacin — and had reduced susceptibility to azithromycin to boot.

Another thing that made H041 special — as special as clones can be, anyway — is that it never reappeared. After its discovery, researchers in Kyoto and Osaka intensified their surveillance, trying to uncover it again and track its spread through the population. However, their search for H041 turned up empty handed. But other ceftriaxone-resistant strains have been documented around the world. Continue reading

STD Awareness: Why Should You Care About Oral Gonorrhea?

Image: CDC

An illustration of Neisseria gonorrhoeae, the bacteria that cause gonorrhea. Image: CDC

When I say “gonorrhea,” you might think of genitals that feel as though they have been set ablaze, or perhaps a viscous fluid oozing from the urethra. But gonococci, the bacteria that cause gonorrhea, can also set up camp in the pharynx after being transmitted into a mouth and down a throat when its new host gave oral sex to its old host. Indeed, performing oral sex on multiple partners has been found to increase risk for an oral gonorrhea infection (more properly called pharyngeal gonorrhea).

If you read our September 2012 article on gonorrhea of the throat, you might remember these fun facts: Oral gonorrhea goes away within three months, even without treatment! Plus, these infections rarely have symptoms. Why, then, should you care about a gonorrhea infection in your throat? You’re not likely to notice it’s there, and it’ll go away on its own anyway.


Many researchers believe that the throat is an incubator for antibiotic-resistant gonorrhea.


Well, aside from the possibility of transmitting a gonorrhea infection from your throat to someone’s genitals, there’s one other thing to care about: the development of antibiotic resistance.

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. If gonorrhea evolves complete resistance to the drugs we use to cure it, we could find ourselves sent back in time, to the days when gonorrhea was untreatable — and responsible for infertility, blindness, and chronic pain. While scientists figure out how to address this emerging threat, you can do your part by avoiding gonorrhea in the first place — and that includes using condoms and dental dams to prevent oral gonorrhea infections.

So, while it sounds like a blessing that gonorrhea of the throat rarely has symptoms, there’s actually a drawback: An oral gonorrhea infection probably won’t be effectively treated — or even identified in the first place. And these hidden throat infections are likely to be helping to drive the development of antibiotic resistance. Continue reading