There has been a lot of attention paid recently to plasmid-borne colistin resistance. The presence of MCR-1 gene has now been examined in large collections of clinical bacterial isolates obtained during the past few years. Perhaps not surprisingly the MCR-1 gene was present at low frequency.
Here is a link to the CNN interview about MCR-1. I also indicated in my discussion with the CNN the need for improved diagnostics, but that did not make it into the article.