SILVER SPRING, Md., May 26 (UPI) -- A person in the United States was found to have a strain of E. coli resistant to the last-resort antibiotic colistin, raising concern among public health officials because they do not know where she picked it up.
The 49-year-old Pennsylvania woman is the first person in the country found to have the strain, which was detected last month in her urine, after first being discovered in a small number of people in China and elsewhere in Europe.
The U.S. Centers for Disease Control and Prevention is working with Pennsylvania health officials to determine how she got the drug-resistant pathogen, checking her recent history at hospitals or other medical facilities.
"It basically shows us that the end of the road isn't very far away for antibiotics -- that we may be in a situation where we have patients in our intensive-care units, or patients getting urinary tract infections for which we do not have antibiotics," Dr. Tom Frieden, director of the CDC, told the Washington Post.
The woman sought treatment for a urinary tract infection on April 26, according to a report published in the journal Antimicrobial Agents and Chemotherapy, reporting no previous travel or other recent medical treatment.
The E. coli strain resistant to colistin was found in 2015 in China in pigs, raw pork meat and a small number of people in China, and later found in Europe.
Although researchers do not yet know how the woman was infected with the colistin-resistant strain, the CDC and U.S. Department of Agriculture found a colistin-resistant strain in a sample from a pig intestine in the United States in the last several weeks.
The E. coli strain contains a colistin-resistant gene called mcr-1, which can be copied and transferred between bacteria through a small piece of DNA called a plasmid -- which can be spread within the same type of bacteria or other similar types, preventing the need for bacteria to evolve to be resistant.
"Colistin is one of the last efficacious antibiotics for the treatment of highly resistant bacteria," Dr. Patrick McGann, a researcher at the Multidrug Resistant Organism Repository and Surveillance Network at the Walter Reed Army Institute of Research, said in a press release. "The emergence of a transferable gene that confers resistance to this vital antibiotic is extremely disturbing. The discovery of this gene in the U.S. is equally concerning, and continued surveillance to identify reservoirs of this gene within the military healthcare community and beyond is critical to prevent its spread."
In their report, researchers at the Walter Reed Army Institute of Research say they have not found the resistant strain in other patients. They caution, however, they have only been running more exhaustive tests for resistance in the last few weeks since confirming the Pennsylvania woman had the bug.