In November 2015, researchers discovered a colistin-resistant E. coli bacterium strain, and since then, people around the world have begun a proactive search, trying to locate instances of colistin-resistant bacteria.
Scientists released nearly 100 reports on the strain, which researchers have found in more than two dozen countries — including the U.S. — in pets, livestock, seagulls, and even people. In May, doctors found a colistin-resistant strain of E. coli a woman patient, the first human-borne instance of such resistance found in the U.S.
The number of antibiotic-resistant bacteria could grow over the next few years, and researchers have been concerned — but they’re also expecting the day when a completely drug-resistant strain could emerge. According to the National Geographic articles, colistin hasn’t been used regularly since the 1950s because it’s toxic and, therefore, is considered the last weapon against antibiotic-resistant bacteria. However, as it was less-prescribed for humans, it became more widely used within the livestock industry — allowing the bacterium to develop colistin resistance.
Researchers have found this resistance, called mcr-1, in numerous places, including China. Furthering their concern is the how mcr-1 antibiotic resistance is passed from one bacterium strain to another — it’s the first incidence of plasmid resistance — meaning it can transfer its resistance to other bacteria or vice-versa. Either way will end with the same result: bacteria resistant to all antibiotics.
According to the ABC News article, another issue is that pharmaceutical companies are not properly incentivized to create new antibiotics because of the high resistance incident rates. Drug company leaders found that investing the resources needed to create new antibiotics has a limited return as bacteria quickly develop resistance to new antibiotics.