A “superbug” that is resistant to colistin — the antibiotic of last resort — was recently found in a U.S. patient with a urinary tract infection. Sarah Fortune, professor of immunology and infectious diseases at Harvard Chan School, discusses the danger posed by pan-resistant bacteria and how best to fight it.

Just how big a problem is this new “superbug”?

The media makes it sound catastrophic, but this particular case of antibiotic resistance — which was found in a woman who has now recovered — is probably not quite as new as some recent reports have suggested. The U.S. actually has seen some colistin-resistant organisms over the past ten years. However, this is the first appearance of what is called plasma-mediated colistin resistance — which means that a gene called mcr-1, which enables bacteria to be resistant to colistin, is carried on a piece of DNA called a plasmid that can be rapidly exchanged between organisms, so that other bacteria can become resistant.

Although this particular case of antibiotic resistance may not be as acute as the media makes it sound, in general these increasingly high-level resistances are an enormous problem. We should be scared enough that we do something about it while we still have antibiotics that work. I think it is easy to take for granted having an arsenal of really effective antibiotics—we have about 100 or so right now. But bacteria are going to evolve resistances to them, and we must be mindful of that.

 

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