Will disease-causing pathogens eventually outsmart all the drugs designed to kill them?
emergence of a dangerous mutation that can make some bacteria resistant
to almost all known antibiotics has infectious disease experts worried.
The rise of antibiotic resistance has concerned scientists for years,
but the new mutation poses some new threats. The mutation, called MDN-l,
jumps easily from one strain of bacteria to another, and it has been
found in gram negative bacteria such as Klebsiella pneumoniae
, which has already caused outbreaks in hospitals in the US and abroad.
The British medical journal Lancet Infectious Diseases
has reported that bacteria with the MDN-l gene has become increasingly
common in India and Pakistan and has been found in patients in the
United Kingdom and the US who received medical care in those countries.
of a new antibiotic resistance mechanism in India, Pakistan, and the
UK: a molecular, biological, and epidemiological study,"
isolates from India were from community acquired infections, indicating
MDN-1 is widespread in the environment. The authors say the problem is
serious, and that possibilities for international spread are "clear and
frightening." The mutation makes e. coli and Klebsiella pneumoniae
bacteria resistant to nearly all powerful carbapenem antibiotics, often the last resort when other drugs have failed.
A New York Times story by Donald McNeil
says the CDC noted the first three cases of NDM-l in US patients in
June and advised doctors to be alert for MDN-l in patients who received
medical care in South Asia. (The initials, the Times
says, stand for New Delhi metallo-beta-lactamase.) Experienced surgeons
and sophisticated hospitals in India provide less expensive care than is
available in Europe and the US, increasing the number of medical
tourists seeking organ transplants, cosmetic surgery and other complex
One of the Lancet
authors, Tim Walsh, is quoted in a Guardian story by Sarah Boseley
saying the emerging mutant may herald the end of antibiotics. "This is
potentially the end," he said. "There are no antibiotics in the
pipeline that have activity against MDN-l producing enterobacteriaceae.
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."
MRSA and Clostridium difficile
two other common health care-associated infections, are gram positive.
Gram positive and gram negative bacteria differ in the structure of
their cell walls. The Lancet
article says gram negative
bacteria pose the greater threat to public health because increase of
resistance is faster in gram negative bacteria, and because few new
antibiotics are being developed to treat gram negative bacterial
infections and none fight MDN-l.
Henry Blumberg, a professor
of medicine and epidemiology at Emory University School of Medicine, was
not involved in the study, but he is alarmed about the emergence of
multi-drug resistant organisms. "We are getting close to the
post-antibiotic era," he is quoted as saying in a PBS news blog by Talea Miller.
"We are going to have organisms that are resistant to all the
antibiotics we have" and that are essentially untreatable. The end of
antibiotics could plunge medicine nearly a century backwards.