Researchers have announced that for the first time, evidence of salmonella resistant to ‘last resort’ antibiotics has been discovered in the United States. The evidence comes in the form of a gene called mcr-3.1 that causes the antibiotic resistance. Though the gene has already been identified in Asia, researchers say this is the first time it has been identified in a sample taken from a patient in the US.
The alert comes from North Carolina State University, where researchers participate in the routine monitoring of salmonella samples for evidence of bacteria resistant to the drugs typically used to treat the infections. According to new research from the university, one sample out of 100 recently tested was found to contain the mcr-3.1 gene.
The sample was part of a batch taken from the southeastern United States from 2014 to 2016 — the infected sample was dated from 2014. Of note, the patient from which the sample was collected had traveled to China two weeks before becoming ill from a salmonella infection.
The mcr-3.1 gene was found in 2015 to have moved from a chromosome to a plasmid in China, according to the research’s corresponding author Siddhartha Thakur. This change ‘paves the way for the gene to be transmitted between organisms,’ he said. ‘Once mcr-3.1 jumped to the plasmid, it spread to 30 different countries, although not – as far as we knew – to the U.S.’
The sample discovery indicates that salmonella resistant to ‘last resort’ antibiotics may be present in the US, though it’s unclear how widespread it may be. According to the CDC, salmonella is responsible for around 23,000 hospitalizations and 450 deaths in the US annually.