Plagues, Pestilences and Diseases
Antibiotics' efficiency crashes due to global spread of
drug-resistant bacteria
Gene giving high levels of resistance to drugs found in increasingly
prevalent intestinal bacteria
* Sarah Boseley, health editor
* The Guardian, Wednesday 11 August 2010
Antibiotics pills The efficiency of antibiotics is decreasing due to
the spread of a bacterial gene conferring high levels of drug
resistance. Photograph: Murdo Macleod for the Guardian
International travel and medical tourism have led to the rapid, global
spread of drug-resistant bacteria that may presage the end of
antibiotics and leave doctors struggling to treat infected patients,
scientists warn today.
A new gene conferring high levels of resistance to almost all
antibiotics has been found to be widespread in forms of gut bacteria
that can cause potentially life-threatening pneumonia and urinary tract
infections.
In just three years, says Professor Tim Walsh of Cardiff University who
discovered the gene, it has grown in prevalence from being rarely
observed at all to existing in between 1% and 3% in patients with
Enterobacteriaceae infections in India.
"It is absolutely staggering," said Walsh. "Because of international
travel, globalisation and medical tourism, [the gene] now has the
opportunity to go anywhere in the world very quickly."
Walsh's paper on the spread of drug-resistant bacteria containing the
gene appears today in the Lancet infectious diseases journal.
He and his colleagues have found NDM-1 (New Delhi
metallo-beta-lactamase) 1 positive bacteria not only in India and
Pakistan but also in the UK. Some of the infected British patients had
travelled to India for kidney or bone marrow transplants, dialysis,
pregnancy care or burns treatment, while others had undergone cosmetic
surgery.
Walsh says it is not possible to know how widespread the bacteria now
is in the UK. The Health Protection Agency has issued an alert, but
doctors report only those cases they treat.
Alarmingly, there are only two antibiotics that still work against NDM
1-producing bacteria, and the likelihood is that they will also be
overcome before long.
"In many ways, this is it," he said. "This is potentially the end.
There are no antibiotics in the pipeline that have activity against NDM
1-producing Enterobacteriaceae."
Even if scientists started work immediately on discovering new
antibiotics against the threat, he added, there will be nothing
available soon.
"We have a bleak window of maybe 10 years, where we are going to have
to use the antibiotics we have very wisely, but also grapple with the
reality that we have nothing to treat these infections with.
"It is the first time it has got to this stage with these type of
bacteria."
Walsh and his colleagues' work also shows that the NDM 1-producing
bacteria are widespread not only in hospitals but quite probably in the
wider community in India, where contamination of drinking water allows
gut-borne bugs to be transmitted easily. Drug-resistant bacteria could
also potentially be passed from one person to another in the UK, he
said.
Ten years ago, scientists believed the greatest threat from
drug-resistant infections involved what are known as Gram-positive
bacteria, which include the so-called superbug MRSA
(methicillin-resistant staphylococcus aureus).
But now, says the Lancet paper, clinical microbiologists increasingly
agree that multidrug-resistant Gram-negative bacteria, which thrive in
the gut, pose the greatest risk to public health.
Not only is the genes' resistance to antibiotics growing more rapidly,
but there are fewer new drugs to fight them.
Walsh discovered the NDM 1 gene after investigating the case of a
patient in Sweden who was admitted to hospital in India infected with
Klebsiella pneumoniae and E. coli bacteria.
The gene made the bacteria resistant to the group of antibiotics called
carbapenems. The carbapenems are normally kept for emergencies and used
when bacteria is found to be resistant to more commonly prescribed
antibiotics.
The gene is carried on a plasmid, a small section of DNA that can move
from one bug to another, passing on drug-resistance as it goes. These
have, according to the paper, "an alarming potential to spread and
diversify among bacterial populations."
Walsh says: "The plasmids are highly promiscuous."
Given the likely worldwide spread of these multidrug-resistant
bacteria, the paper says: "It is disturbing … to read calls in the
popular press for UK patients to opt for corrective surgery in India
with the aim of saving the NHS money.
"As our data shows, such a proposal might ultimately cost the NHS
substantially more than the short-term saving and we strongly advise
against such proposals."
In a commentary in the journal, Johann Pitout from the University of
Calgary in Canada calls for patients who have received medical
treatment in India to be screened before they are admitted for care
back home. He warns that medical tourism, fuelling the spread, could
grow in India by 30% every year over the next five years.