Sometimes, when antibiotics are used to kill disease-causing bacteria, a genetic mutation here or a different protein there help the bacteria survive. With all of their competitors wiped out, these new, antibiotic-resistant bacteria are free to reproduce, passing on their genes to descendents. Carbapenem-resistant Enterobacteriaceae—which the Centers for Disease Control and Protection have dubbed “nightmare bacteria”— are, at this point, resistant to pretty much everything we have and, over the past 18 years, have been slowly gaining ground.
Most of the people who caught these bugs, though, were either in the hospital—most likely a long-term, acute-care hospital—or had been there recently. One of the CDC's worries is that CREs could escape from the hospital setting. This, unfortunately, seems to be happening, says Maryn McKenna on her blog Superbug.
[T]he hospitals where this resistance factor was identified were what is called “community” hospitals, that is, not academic referral centers. That’s an important distinction, because academic medical centers tend to be where the most cutting-edge care is performed, and where the sickest people are. As a result, they are where last-resort antibiotics are used the most, and therefore where resistance is most likely to emerge. That CRE was found so widely not in academic centers, but rather in community hospitals, is a signal that it is probably moving through what medicine calls “the community,” which is to say, anywhere outside healthcare. Or, you know, everyday life.
The prevalence of CRE seems to be growing, says McKenna, reporting on a new study. From 2008 to 2012, in the American southeast, the rate of detection of the bacteria increased five-fold. Most of these cases (288 of 305, or 94 percent) were connected to hospital visits, but some weren't. Some of this five-fold increase is attributable to better detection methods, the scientists say, but some of it is a sign that these antibiotic-resistant bacteria are taking hold.