Some strains of STD showing signs of becoming resistant to all treatments
 |
As some strains of gonorrhea,
shown here through a microscope, grow more drug resistant, the world may
soon face a strain that can’t be killed by any known antibiotics, say
experts.
|
Joe Millar/CDC
|
Sexploration — By Brian Alexander
|
Incurable gonorrhea may be next superbug
The world may soon be facing a strain of gonorrhea that can’t be killed by any known antibiotic, warn researchers. The STD is showing signs of becoming resistant to even the last known class of antibiotics to effectively fight it. |
In recent years, as the
disease has evolved, medications once proven to kill the bacteria have
become less effective except one, a class of antibiotics called
cephalosporins. Now some strains of gonorrhea are showing signs of being
resistant to even that, Ison told those at a scientific meeting last
week in Edinburgh, Scotland.
"If this problem isn't addressed, there's a very real
possibility that gonorrhea will become a very difficult infection to
treat," she said. Gonorrhea is the second most commonly reported
infectious disease in the United States. In 2008, there were 336,742
official cases, but this number, the most recent available from the
Centers for Disease Control and Prevention, may vastly underestimate the
true number.
“We
will probably have something like 700,000 cases of gonorrhea this year,”
suggested Dr. Edward W. Hook, professor of medicine at the University
of Alabama at Birmingham and an expert on STD infections.
Not all of those who are
infected know it, contributing to the problem. Undiagnosed cases, or
infections that are unsuccessfully treated and then linger without
obvious symptoms, can create serious health problems. For example,
teenage girls between 15 and 19 account for more cases than any other
age group. If they aren’t cured, they risk pelvic inflammatory disease,
infertility or ectopic pregnancies. People infected with gonorrhea are
also about three times more likely to become infected with HIV should
they come into contact with the virus.
“The other major cost is infection of children born
to infected mothers,” Hook explained. “And rarely you can get gonorrheal
infections of heart valves, and arthritis.”
History of
being hard to treat
Gonorrhea has a long history of evading medicine’s attempts to cure it. In the 1930s, sulfa-based drugs worked, but soon lost potency as the bacteria adapted. Penicillin came up to bat in the 1940s. In New York City, Los Angeles, and points in between, posters appeared stating “Penicillin Cures Gonorrhea in 4 Hours,” sometimes underneath words urging citizens to buy war bonds to “Thrash the Axis.”
Gonorrhea has a long history of evading medicine’s attempts to cure it. In the 1930s, sulfa-based drugs worked, but soon lost potency as the bacteria adapted. Penicillin came up to bat in the 1940s. In New York City, Los Angeles, and points in between, posters appeared stating “Penicillin Cures Gonorrhea in 4 Hours,” sometimes underneath words urging citizens to buy war bonds to “Thrash the Axis.”
Just
as defeating Hitler and the Japanese emperor had become an
all-consuming national priority, health officials, armed with the new
miracle drug penicillin, offered hope that the scourge of “VD” could be
wiped out, too.
Penicillin
was a miracle, but eventually doctors had to use more and more to kill
the bug. Still, a shot of penicillin remained the treatment of choice
until 1985, when rising resistance to penicillin, and the fact that many
people are allergic to it, forced health officials to give other
antibiotics their turns.
But
as they did, strains of the bacteria morphed to make the antibiotics
less effective. A February report from a group of Taiwanese doctors
found that during the five years between 1999 and 2004, 40 percent of
gonorrhea isolated from their patients was resistant to penicillin,
tetracycline, erythromycin and ciprofloxacin, all drugs which used to
kill off gonorrhea like magic bullets.
The cephalosporins are all that’s left.
In May of 2009, doctors
at Sydney, Australia’s Prince of Wales Hospital reported two cases of
failed treatment of gonorrhea of the pharynx (typically resulting from
oral sex or oral-anal contact). The drug they used is called
ceftriaxone, a cephalosporin given by injection. There have also been
scattered reports of increasing drug resistance to the most commonly
used pill form of cephalosporin, although not in the U.S. so far, said
Dr. Kimberly Workowski, associate professor of medicine at Emory
University and the CDC’s coordinator of STD treatment guidelines. The
CDC monitors the issue through its Gonorrhea Isolate Surveillance
Project which receives reports from health clinics all over the
country.
Workowski
is concerned, though. For one thing, some people who are allergic to
penicillin may also be allergic to cephalosporins.
Since people with some
forms of gonorrhea may not show symptoms, their partners may have no
idea they're infected. The pill form of cephalosporin, which can be used
for uncomplicated rectal or urogenital infections, is “only 70 percent
effective” in treating pharyngeal gonorrhea, she noted. Since infection
of the pharynx often carries no symptoms, people treated for urogenital
infection may not know they carry a pharyngeal infection, too. That
gives the disease a safe harbor from which it can launch infections of
more people.
Resistance
has tended to follow geography and sexual orientation, Workowski
explained. “Traditionally southeast Asia has developed resistant
isolates and then there is a slow spread across [the Pacific],
eventually coming to the U.S.,” she said. Resistant strains also tend to
show up first in men who have sex with men.
Other
drug-resistant STDs
Resistance could also become an issue in other bacterial STDs. About 30 percent of females who contract gonorrhea are co-infected with chlamydia. While chlamydia seems to respond well to medication so far, a small number of strains have shown signs of developing drug-resistance, says Workowski. Hook, however, says he doesn’t know of any resistant strains.
Resistance could also become an issue in other bacterial STDs. About 30 percent of females who contract gonorrhea are co-infected with chlamydia. While chlamydia seems to respond well to medication so far, a small number of strains have shown signs of developing drug-resistance, says Workowski. Hook, however, says he doesn’t know of any resistant strains.
Syphilis has already defeated one drug used to treat
it, azithromycin. Between 2000 and 2004, the prevalence of
azithromycin-resistant syphilis in one San Francisco clinic jumped from
zero percent to 56 percent.
“We have since been looking at azithromycin mutations
in strains from all over the country and world,” said Sheila Lukehart,
research professor of medicine at the University of Washington and an
author of the New England Journal of Medicine report about the San
Francisco clinic. “We’ve found a very a broad distribution of the
specific mutation that gives syphilis antibiotic resistance.”
The good news is that
penicillin still works against syphilis; the treatment consists of two
shots, one in each butt cheek. No credible data suggests that syphilis
has been able to adapt to penicillin, probably, Lukehart explained,
because penicillin attacks a critical site on the bacterium that is so
crucial to the bug’s survival that it can’t change it. Still, the loss
of azithromycin makes infections tough to treat in people allergic to
penicillin since they must be desensitized — often in a hospital — and
then treated.
'Doomsday
scenario'
There are alternatives should gonorrhea prove resistant to the cephalosporins. While a sudden change in the gonorrhea bacteria that leaves it completely resistant to the cephalosporins would be “the doomsday scenario,” Hook said, it’s more likely that the evolution will be gradual. So following the old strategy of increasing doses as the resistance increases will buy time. He also holds out hope that pharmaceutical companies, which see antibiotic development as unprofitable, will suddenly have a big incentive to create new drugs should the cephalosporins lose their effectiveness.
There are alternatives should gonorrhea prove resistant to the cephalosporins. While a sudden change in the gonorrhea bacteria that leaves it completely resistant to the cephalosporins would be “the doomsday scenario,” Hook said, it’s more likely that the evolution will be gradual. So following the old strategy of increasing doses as the resistance increases will buy time. He also holds out hope that pharmaceutical companies, which see antibiotic development as unprofitable, will suddenly have a big incentive to create new drugs should the cephalosporins lose their effectiveness.
Meanwhile, the CDC is
developing other strategies. It is about to start a trial, operated
through the National Institutes of Health, to look at alternative
therapies like giving patients a one-two punch of an oral and an
intramuscular injection using two different classes of antibiotics at
once. Doctors already routinely treat female gonorrhea patients with a
different drug for Chlamydia on the assumption they’ll be infected with
it, too. Ideally, though, researchers will find either a new drug, or
prove an existing antibiotic will work.
Of course, it’s better to prevent an infection in
the first place. Being tested for STDs and using condoms, the same
techniques the military promoted among the troops to fight “VD” back in
World War II before penicillin, are still the best bacterial STD
fighters of all.
Brian
Alexander is the author of the book “America Unzipped: In Search
of Sex and Satisfaction," now in paperback.