BIOTERRORISM: antibiotic resistant organism

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.
http://www.guardian.co.uk/science/2010/aug/11/antibiotics-efficiency-drug-resistant-bacteria