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By Brad Evenson
The National Post - Canada
9-30-2002
Dr. Joshua Lederberg discovered bacteria gene swapping.
Antibiotic-resistant bacteria kill more than 40,000 North Americans a year, and
the numbers will soar unless the so-called super-germs are brought under control,
a new book warns.
The book, The Killers Within, charts the acceleration of resistant infections
that began with a few cases in the late 1980s and is now spiraling out of control.
The germs, once killed easily with standard antibiotics, can disintegrate skin,
clog the lungs and carve golf-ball-size abscesses in flesh.
"The bad bugs are getting stronger and they're getting stronger faster," says
co-author Mark Plotkin, a Smithsonian Institution ethnobotanist whom
Time magazine dubbed a "Hero of the Planet" in 1998. "We feel
like we're looking at almost a hyper-evolutionary period," he says.
While West Nile virus is grabbing headlines for killing about 100 people, the
U.S. Centers for Disease Control and Prevention estimates 44,000 people in
North America die annually of infections from drug-resistant germs.
Some experts believe the numbers are higher. The epidemic comes as pharmaceutical
companies have all but stopped doing research on antibiotics.
"They'd rather develop lifestyle drugs like Viagra and blood-pressure medicine
that you're going to take every day of your life for 40 years," says Dr. Plotkin,
who concedes a few drug companies are pursuing new antimicrobials.
"If you're selling antibiotics, I'm going to take it for a week, and I'm
either going to get better or I'm going to die."
Even the newest types of antibiotics, such as Synercid and Zyvox,
are already threatened by resistant strains.
The book charts the proliferation of three germs in particular: E. faecium,
S. aureus and S. pneumococcus, which
are remarkably common in hospitals. Virtually every major Canadian hospital
has been colonized by these bacteria, including operating theatres and intensive
care wards.
Decades ago, these species could be wiped out with a single dose of penicillin.
But overuse of antibiotics gave the bacteria a chance to develop new genes
that protected them.
"Among the billions of bacteria in a drop of human blood, or on a pinpoint
of skin ... might be a few -- just a few -- with a chance mutation that enabled
them to resist the antibiotic used against them," the book notes.
"If the antibiotic was then removed because the patient felt better and
stopped using it, those few resistant bugs would have an ecological niche, or
clear field, in which to run wild."
Unlike other creatures, bacteria can swap genes between species, so enterococci can
donate genes to staphylococcus.
Joshua Lederberg, the Nobel laureate who discovered
this gene swapping, says the Ebola and West Nile viruses are minor by comparison
with such bacteria.
"The odds of Ebola breaking out are quite low, but the stakes are quite
high," says Dr. Lederberg, a professor at Rockefeller University in New York.
"With antibiotic resistance, the odds are certain and the stakes are just
as high."
Unlike U.S. hospitals, which have
thrown up their hands in the face of drug-resistant enterococci and
other bugs, Canadian hospitals have fought back.
Two of the heroes of The Killers Within are microbiologist Donald Low and infectious
disease specialist Alison McGeer, both from Toronto, who have waged an exhaustive struggle
against drug-resistant germs.
As early as 1991, Dr. Low was warning about the dangers of overuse of antibiotics.
By 1993, a Japanese patient had become infected with the first strain of S. aureus that
could not be killed by Vancomycin, known as the "antibiotic
of last resort."
One of the biggest areas of antibiotic misuse is by doctors who prescribe them
to complaining patients with viral infections.
Antibiotics do not work against viruses and the more often an antibiotic is
given, the more likely a person's natural bacteria will become resistant.
Adding to the medical overuse of antibiotics, North American livestock have
been fed small doses of antibiotics as a growth promoter since the 1950s.
As a result, livestock serve as a reservoir of drug-resistant germs.
One of the reasons the new antibiotic, Synercid, is now threatened with resistance is because cows
are being fed an analogue -- a close chemical cousin -- of the drug with their
dinner.
The book says experimental drugs offer some hope.
Among the most unorthodox of these is a tiny chunk of protein, found in the
thick saliva of the Komodo dragon, a massive carnivore found in Indonesia.
Another promising drug can be found in the skin of African clawed frogs.
In the meantime, infection control and less antibiotic use in humans and animals
is the only strategy, Dr. Plotkin says.
bevenson@nationalpost.com |
