Infectious disease specialists say the
discovery of a mcr-1 gene-carrying strain of E. coli in a Pennsylvania woman
“heralds the emergence of truly pan-drug resistant bacteria.”
The U.S.
Centers for Disease Control and Prevention (CDC) isn’t known to use hyperbolic
language.
Considering
its role in combatting potential outbreaks, it’s often reserved with its word
choice to avoid creating a panic.
Still,
they call carbapenem-resistant Enterobacteriaceae, or CRE, the “nightmare
bacteria” for good reason. The strain is resistant to numerous types of
antibiotics, making an infection nearly impossible to treat.
It’s
deadly in half of those infections.
While
many media outlets have reported about a new strain of CRE resistant to
powerful antibiotics appearing in the United States, it’s actually E. coli, not
CRE. The distinction is important to make, although both are members of the
Enterobacteriaceae family.
The real
problem isn’t the bug. It’s the gene mcr-1, which makes the bug resistant even
to last-ditch antibiotics. And it can quickly pass those genes onto other
bacteria.
The
threat of this survival resistance spreading to other bugs adds a new level of
concern about what options remain to stop these deadly bacteria.
Caring
for patients when no drugs work gives doctors “a feeling of such horror and
helplessness,” said Dr. Tom Frieden, director of the CDC.
And this
new finding highlights a crucial time in modern medicine.
“It
basically shows us that the end of the road isn’t very far away for antibiotics
— that we may be in a situation where we have patients in our intensive care
units, or patients getting urinary-tract infections for which we do not have
antibiotics,” he told The Washington Post.
This has
infectious disease experts concerned because bacteria across the world are
increasingly building defenses against the most powerful antibiotics. And the
development of new antibiotics is falling behind.
Every
year, according to the CDC’s best estimates, 2 million people are infected with
one form of drug resistant bacteria. Of those, 23,000 people die.
The Discovery of mcr-1 in Humans
Researchers
have confirmed the strain of E. coli resistant to colistin, a powerful
antibiotic discovered in the 1950s. Its use was discontinued in the 1970s
because of its toxicity.
The
strain was discovered in the United States last month in the urine of a
49-year-old Pennsylvania woman, according to a report released Thursday by
researchers at Walter Reed National Military Medical Center. She was being
treated for a urinary tract infection, a common source for drug-resistant
infections.
These
types of drug-resistant urinary tract infections are also on the rise in
children, according to recent research.
The woman
hadn’t traveled in five months, puzzling researchers where the strain came
from.
According
to the U.S. Department of Health and Human Services, colistin-resistant E. coli
was previously found in a single sample from a pig intestine. The U.S.
Department of Agriculture is investigating that pig’s farm of origin.
The
potentially deadly bug had been reported in other countries, which to
researchers “heralds the emergence of truly pan-drug resistant bacteria.”
Following
the initial discovery of the mcr-1 gene and its resistance to colistin in China
in November, researchers in Europe and Canada have discovered the bacteria.
While the
finding of mcr-1 is alarming, it’s still rare. Experts say none of the more
than 44,000 Salmonella and 9,000 E. coli/Shigella samples from several gene
databases showed the presence of the mcr-1 gene as of April.
How Drug Resistance Works
Bacteria
follow the mantra, “That which does not kill you only makes you stronger.”
When
antibiotics are used but don’t kill the bacteria, they can learn to develop
resistance.
Because
of this, infectious disease experts have been warning medical officials to use
antibiotics judiciously. This includes Alexander Fleming, who discovered
penicillin in 1928.
“It is
not difficult to make microbes resistant to penicillin in the laboratory by
exposing them to concentrations not sufficient to kill them, and the same thing
has occasionally happened in the body,” he wrote while accepting the Nobel
Prize in 1945. “The time may come when penicillin can be bought by anyone in
the shops. Then there is the danger that the ignorant man may easily underdose
himself and by exposing his microbes to non-lethal quantities of the drug, make
them resistant.”
Routine
use of antibiotics — whether by unnecessary prescriptions in humans or
administering them to animals in water and feed — gives bacteria more
opportunities to develop drug resistance.
Currently
in the United States, half of all antibiotic prescriptions for people may be
inappropriate. This means they’re given out for conditions where they can only
do more harm than good, like the common cold.
Also, the
routine administration of antibiotics to livestock has been a concern for
decades. Once used for growth promotion, farmers continue to give animals small
amounts of antibiotics daily for disease prevention.
All told,
estimates by the U.S. Food and Drug Administration show 80 percent of all
antibiotics sold in the United States are for animals meant for our dinner
plates.
Because
of these kinds of misguided uses, Duke University researchers say the rates of
drug-resistant E. coli infections have doubled in the past five years.
Brian
Krans
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