The threat of a “post-antibiotic era” has moved closer to reality, after the first case of resistance to the “last-resort” antibiotic colistin has been identified in the United States.
Antibiotic resistance, or antimicrobial resistance, occurs when microorganisms develop the ability to escape the effects of drugs that once had the ability to kill them.
According to the Centers for Disease Control and Prevention (CDC), antibiotic-resistant infections affect around 2 million people in the U.S. each year, and more than 23,000 people die as a result of these infections.
Carbapenem-resistant Enterobacteriaceae (CRE) bacteria have become one of the biggest threats for antibiotic-resistant infections in the U.S., responsible for around 9,000 drug-resistant infections each year and 600 deaths.
CRE have developed resistance to almost all available antibiotics, making CRE infections extremely hard to treat. In some cases, these “superbugs” kill almost half of the patients they infect.
Colistin is one of the only antibiotics that has still shown some effectiveness against CRE, but a new report suggests this might be about to change.
In the journal Antimicrobial Agents and Chemotherapy, investigators from the Walter Reed Army Institute of Research (WRAIR) and the Multidrug Resistant Organism Repository and Surveillance Network (MRSN) reveal the first case of colistin resistance in the U.S.
The report reveals that last month, a 49-year-old female presented at a military treatment center in Pennsylvania with a urinary tract infection (UTI).
On testing a urine sample from the women, researchers found that it contained a strain of Escherichia coli – a species of Enterobacteriaceae – that possessed a colistin-resistant gene called mcr-1.
The mcr-1 gene first arose in China late last year, identified in a pig infected with E. coli. The colistin-resistant gene has since been found in parts of Europe and Canada.
The case detailed in the new report represents the first time mcr-1 has been found in the U.S.
Health officials believe the discovery is a cause for concern; this drug-resistant gene can spread to other bacteria, and if it does, it could mean the end for what is already a last-resort antibiotic.
“Colistin is one of the last efficacious antibiotics for the treatment of highly resistant bacteria. 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.”
Study co-author Dr. Patrick McGann, MRSN, WRAIR
Dr. McGann and colleagues say the discovery has prompted an “urgent public health response” to prevent the spread of mcr-1, which involves active surveillance of mcr-1 through collection and testing of bacterial samples.
“Through our surveillance system, we have the unique ability to coordinate source information with susceptibility and sequencing data, and if need be, go back to understand changes in infecting organisms to best treat infection and track emerging multidrug resistant organisms,” notes study co-author Emil Lesho, director of the MRSN and WRAIR.
In an interview yesterday, CDC Director Dr. Tom Frieden said the new report shows the “end of the road isn’t very far away for antibiotics,” adding that the situation may arise where a patient with a UTI cannot be treated.
“I’ve been there for TB [tuberculosis] patients. I’ve cared for patients for whom there are no drugs left,” he added. “It is a feeling of such horror and helplessness. This is not where we need to be.”