Gettyimages.ru Kateryna Kon
The World Health Organization describes antibiotic-resistant bacteria as “one of the 10 largest global public health threats facing humanity”.
And now, US researchers have found a gene that could signal an attack from a superbug.
Researchers from the University of Georgia Center for Food Safety (CFS) collected wastewater from an urban area in the state, to test for the presence of the MCR-9 gene in naturally occurring bacteria. When present in bacteria, this gene indicates that the bacteria are resistant to colistin, one of the world’s most important antibiotics.
Colistin is considered an “antibiotic of last resort,” the researchers explained in a report to the journal Global Antimicrobial Resistance last month. Because it is used to treat infections that other antibiotics cannot use, there is likely no medicine that can be used once the microbe has developed resistance to it.
Colistin is banned in cattle in the United States, although the drug is most commonly used on animals in countries with less stringent regulations, such as India and China. The researchers’ discovery suggests that whether through food imports or global travel, colistin-resistant bacteria were able to establish themselves in the United States.
Georgia researchers found MCR-9 in Morganella morganii, a bacterium that, albeit rarely, can cause infection in humans. However, the gene is transmitted in plasmids, or strands of DNA found within cells that can replicate on their own, independently of the cell. Plasmids can be transmitted to other forms of bacteria, which means that microbes such as E. coli and Salmonella that commonly affect humans can easily acquire the MCR-9 gene and become resistant to antibiotics.
The fact that MCR-9 was discovered in an often-overlooked bacterium in an area where colistin is not used is cause for concern, senior researcher Ismat Kassem told University of Georgia News on Tuesday, and is evidence of the gene spreading in the United States unnoticed by scientists.
“If we don’t deal with it now, we are endangering human and animal medicine as we know it and that could have huge repercussions on health and the economy,” Qassem said. “It’s a serious problem that requires multi-sectoral attention so that we can address it properly.”