A gene causes antibiotic-resistant bacteria, an important antibiotic of last resort has been discovered circulating in Georgia’s wastewater.
The Mcr-9 gene is found in gram-negative bacteria, such as Salmonella and E. Coli, and is part of the mobile colistin resistance (mcr) gene family that allows bacteria to become colistin resistant. Colistin is a key antibiotic in the fight against multidrug-resistant bacterial strains, often used against infections that do not respond to other antibiotics.
If multidrug-resistant strains were to acquire an MCR gene, it would mean that one of our last remaining weapons against antibiotic resistance is no longer effective.
As such, the scientists closely monitored the mcr family and until now thought it was not prevalent in the United States. However, new research from the University of Georgia’s Center for Food Safety (CFS) has made an overwhelming finding: Isolates from wastewater in Georgia tested positive for mcr-9.1. Additionally, these isolates are resistant to colistin, as well as a host of other important antibiotics.
Research suggests that the mcr-9 gene may be much more prevalent than previously thought, requiring significantly more investigation into the establishment of MCR variants in the United States. An abridged version of the research was published in the Journal of Global Antibiotic Resistance.
Colistin is used as an agricultural antibiotic by many countries and to date this has been attributed as a determinant of colistin resistance in bacteria. It has since been banned in the United States in an attempt to curb the possibility of MCR spreading across the country, but the success of such measures is unclear.
In this study, scientists isolated samples from wastewater in Georgia, following reports that bacteria carrying the mcr genes were found in New York, Connecticut, New Jersey and Michigan.
By taking a large amount of sewage and returning it to the laboratory to isolate the bacteria inside, the researchers discovered Morganella morganii (a gram-negative bacterium found as normal flora within the human and animal gut) with a mcr gene. -9.1. When tested on antibiotic plates, it showed high resistance to colistin, as well as many other important antibiotics commonly used against bacterial infections.
According to the authors, this marks the first sighting of the mcr-9.1 gene in M. morganii and the first time that mcr has been isolated from a wastewater sample – and that’s bad news for scientists concerned about antibiotic resistance. They are now calling for meaningful collaboration to address the crisis, which is listed by the WHO as “one of the top 10 global public health threats humanity faces”.
“If we don’t address it right now, we are jeopardizing human and animal medicine as we know it and that can have huge repercussions on health and the economy,” said Issmat Kassem, assistant professor at the College of Agricultural and Environmental Sciences. in a statement to Phys Org.
“It is a dangerous problem that requires the attention of multiple sectors to be able to address it properly”.
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