“NDM, MCR-1 resistance genes found in same E coli isolates in China”
“Chinese scientists yesterday reported on the emergence of extensively drug-resistant (XDR) Escherichia coli carrying both New Delhi metallo-beta-lactamase (NDM) and MCR-1 genes in chickens at slaughter in China and detailed the features of two novel NDM-carrying plasmids.
In a letter in the Journal of Antimicrobial Chemotherapy, the investigators said they collected 50 fecal samples from chickens at a slaughterhouse in Qingdao, which sits on the Yellow Sea in eastern China. They recovered 33 E coli isolates from the samples.
Two of the strains showed resistance to imipenem and had an XDR pattern. Polymerase chain reaction and Sanger sequencing confirmed that the strains harbored both NDM and MCR-1. In one isolate the resistance genes were located on separate plasmids, while on the other the NDM gene was on a plasmid and the MRC-1 gene was on a chromosome. Plasmids are mobile pieces of DNA that can transfer to other bacteria of either the same or different species.
NDM-1 was first detected in 2008 and confers resistance to a broad range of beta-lactam antibiotics, including carbapenems. MCR-1 was first identified in China in 2015 and confers resistance to colistin, an antibiotic of last resort. So the detection of both of them in the same bacterium warrants increased concern over XDR pathogens that may be untreatable.”