A gene has been found in sewer water in Georgia that causes bacteria to be resistant to one of the world’s most important antibiotics, colistin. The presence of the MCR-9 gene is appalling for public health because it causes antimicrobial resistance. This is a problem that the World Health Organization has declared “one of the top 10 global public health threats facing humanity.”
Researchers from the University of Georgia’s Center for Food Safety (CFS) collected sewage water from an urban setting in Georgia to test for the MCR gene in naturally present bacteria. The team was headed by College of Agricultural and Environmental Sciences assistant professor Issmat Kassem, whose research narrows down on MCR’s presence around the world.
The team found the gene in one test. This means that the gene is becoming established in the U.S.
The gene was found in the bacteria, Morganella morganii. This marked the first time that MCR was found in M. morganii, which is troublesome because it is a bacterium not often tested by researchers.
Earlier, it was thought that agricultural practices led to the spread of MCR. Countries like China and India use colistin antibiotics in livestock. It is considered a “last resort” antibiotic because it can kill infections that other antibiotics cannot. Its frequent use means that some bacteria are becoming resistant to it which is quite problematic.
Colistin is banned in the U.S. for use in food animals. However, MCR can be spread through global travel and the import of foods from other countries. Results of the CFS study prove that the U.S. is facing the same threat with this as the rest of the world.
The gene is transmitted in plasmids, which are strands of DNA found inside cells that can replicate on their own, without the cell. A plasmid with antimicrobial resistance found in one type of bacteria can transmit to other types of bacteria. So, E. coli and Salmonella that commonly cause outbreaks in humans can potentially carry MCR, turning them from treatable illnesses to potentially deadly infections.
“If we don’t tackle 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,” Kassem said. “It’s a dangerous problem that requires attention from multiple sectors for us to be able to tackle it properly.”
The findings from the research were printed urgently in a short format manuscript out now in the Journal of Global Antimicrobial Resistance. It was funded through a CFS grant and other researchers involved were Jouman Hassan, David Mann, Shaoting Li, and Xiangyu Deng.