Via CIDRAP, a June 28 report by Chris Dall: New colistin resistance gene identified in China. Excerpt:
Researchers in China have discovered another gene that confers resistance to the last-resort antibiotic colistin.
In a study yesterday in mBio, the researchers report that the MCR-3 gene was discovered in a fecal sample obtained from an apparently healthy pig at a farm in Shandong province during a routine surveillance study of antimicrobial resistant bacteria. The gene was located on a colistin-resistant Escherichia coli isolate, on a plasmid that contained 18 additional antibiotic resistance genes.
The authors of the study say they're concerned the gene may already be widely disseminated, and that scientists should be on the lookout for it. "Screening for the mcr-3 gene should be urgently included in the surveillance of colistin-resistant Gram-negative pathogens from animals, humans, and the environment," they write.
A third mobile colistin-resistance gene
The discovery was made by several members of the research team that first reported the discovery of the mobile colistin resistance gene MCR-1 in E coli from pigs, pork products, and humans in China in November 2015. That finding raised international concern, given that colistin is an antibiotic of last resort for multidrug-resistant bacterial infections. The gene's location on plasmids, which are highly mobile pieces of DNA that can be shared within and between different bacterial species, means that resistance to colistin can quickly spread.
Since then, MCR-1 has been identified in bacteria from humans, animals, and the environment in more than 30 countries, including the United States, and studies have documented the spread of the gene to the clinical setting in China. Earlier this year, Chinese scientists reported an outbreak of MCR-1–carrying Klebsiella pneumoniae among patients in a pediatric leukemia ward.
In addition, six different variants of the MCR-1 gene have been reported, along with a second mobile resistance gene, MCR-2.
