In fact, more than 60% of the Gram negative isolates in our hospital (in-patients) appear to be producing an enzyme called extended spectrum beta lactamases (ESBL). These ESBL-strains are often resistant to other classes of antibiotics as well, narrowing therapeutic options. In a subset of cases, these bugs turn up as resistant to almost all the antibiotics we test.
But, I am yet to come across a case where the isolate was resistant to colistin and polymyxin B. No clinician would even think of using these drugs if other options are available. But, if, as the article reports, these organisms turn out to be resistant to even these last-resort drug... we can safely assume that we are in deep shit.