Google – AFP, 21 May 2013
An Afghan
woman holds a child in a tuberculosis section of the main
hospital in Herat on
April 9, 2012 (AFP/File, Aref Karimi)
|
PARIS —
Scientists said Tuesday they had managed to kill lab-grown tuberculosis (TB)
bacteria with good old Vitamin C -- an "unexpected" discovery they
hope will lead to better, cheaper drugs.
A team from
Albert Einstein College of Medicine in New York made the accidental find while
researching how TB bacteria become resistant to the TB drug isoniazid.
The
researchers added isoniazid and a "reducing agent" known as cysteine
to the TB in a test tube, expecting the bacteria to develop drug resistance.
Instead,
the team "ended up killing off the culture", according to the study's
senior author William Jacobs, who said the result was "totally
unexpected".
Reducing
agents chemically reduce other substances.
The team
then replaced the cysteine in the experiment with another reducing agent --
Vitamin C.
It, too,
killed the bacteria.
"I was
in disbelief," said Jacobs of the outcome published in the journal Nature Communications.
"Even
more surprisingly... when we left out the TB drug isoniazid and just had
Vitamin C alone, we discovered that Vitamin C kills tuberculosis."
The team
next tested the vitamin on drug resistant strains of TB, with the same outcome.
In the lab
tests, the bacteria never developed resistance to Vitamin C -- "almost
like the dream drug", Jacobs said in a video released by the college.
He stressed
the effect had only been demonstrated in a test tube so far, and "we don't
know if it will work in humans", or which dose might be useful.
"But
in fact before this study we wouldn't have even thought about trying this study
in humans."
In March,
disease experts warned of a "very real" risk of an untreatable TB
strain emerging as more and more people develop drug resistance.
In 2011,
there were believed to be some 12 million TB cases in total -- 630,000 of them
of the multi-drug resistant (MDR) variety which does not respond to the most
potent drugs -- isoniazid and rifampin.
Extensively
drug resistant (XDR) TB, does not respond to an even wider range of drugs.
TB was
declared a global health emergency by the World Health Organisation (WHO) 20
years ago, but remains a leading cause of death by an infectious disease
despite a 41-percent drop in the death rate from 1990 to 2011.
In 2011,
8.7 million people fell ill with TB and 1.4 million died, said the WHO.
Over 95
percent of TB deaths occur in low- and middle-income countries, and it is a
leading killer of people with HIV.
An airborne
disease of the lungs, tuberculosis is usually treatable with a six-month course
of antibiotics.
Resistance to
TB drugs develops when treatment fails to kill the bacteria that causes it --
either because the patient fails to follow their prescribed dosages or the drug
doesn't work.
It can also
be contracted through rare forms of the disease that are directly transmissible
from person to person.
MDR TB in
the United States can cost as much as $250,000 (200,000 euros) per patient to
treat.
XDR TB
requires about two years of treatment with even more expensive drugs that cause
side-effects and offer no guarantee of a cure.
The authors
of the new study urged further research into the potential uses of Vitamin C in
TB treatment, stressing it was "inexpensive, widely available and very
safe to use."
"This
would be a great study to consider because we have strains of tuberculosis that
we don't have drugs for, and I know in the laboratory that we can kill those
strains with Vitamin C," said Jacobs.
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