WASHINGTON • A superbug resistant to all known medications has been found in the United States for the first time, US health officials reported, raising deep concerns the bacteria could pose serious danger for routine infections if it spreads.
"We risk being in a post-antibiotic world," said Dr Thomas Frieden, director of the US Centres for Disease Control and Prevention, referring to the urinary tract infection of a 49-year-old Pennsylvania woman.
Dr Frieden, speaking at a National Press Club luncheon in Washington, DC, said the infection was not controlled even by colistin, an antibiotic that is reserved for use against "nightmare bacteria". The infection was reported on Thursday in a study appearing in Antimicrobial Agents and Chemotherapy, a publication of the American Society for Microbiology.
The patient is well now, but the case raises the spectre of superbugs that could cause untreatable infections because the bacteria can easily transmit their resistance to other germs that are already resistant to additional antibiotics.
The resistance can spread because it arises from loose genetic material that bacteria typically share with one another.
The study's authors said the superbug itself had first been infected with a tiny piece of DNA called a plasmid, which passed along a gene called mcr-1 that confers resistance to colistin.
"(This) heralds the emergence of truly pan-drug resistant bacteria," said the study, which was conducted by the Walter Reed National Military Medical Centre.
"To the best of our knowledge, this is the first report of mcr-1 in the USA," the authors say.
The woman had not travelled outside the United States, so she could not have acquired the resistant bacteria elsewhere, Dr Frieden said.
"We know now that the more we look, the more we are going to find," he added. "We risk being in a post-antibiotic world."
Colistin has been available since 1959 to treat infections caused by E. coli, Salmonella and Acinetobacter, which can cause pneumonia or serious blood and wound infections. It was abandoned for human use in the 1980s due to high kidney toxicity, but is widely used in livestock farming, especially in China.
However, colistin has been brought back as a treatment of last resort in hospitals and clinics as bacteria have started developing resistance to other, more modern drugs.
"We need to do a very comprehensive job of protecting antibiotics so we can have them and our children can have them," Dr Frieden said, calling for more research into new antibiotics and better stewardship of existing drugs.
"The medicine cabinet is empty for some patients," he added. "It is the end of the road for antibiotics unless we act urgently."
The study said continued surveillance to determine the true frequency of the mcr-1 gene in the US was critical. The mcr-1 gene was found last year in people and pigs in China, raising alarm.
REUTERS, NEW YORK TIMES, AGENCE FRANCE-PRESSE