In May, researchers identified for the first time a bacterial infection in the US that was resistant to the last-resort antibiotic colistin. Colistin was the last remaining antibiotic effective against all bacteria in the country – a weapon of last resort. This particular infection was sensitive to other antibiotics and was cured, but the presence of colistin resistant bacteria in the US (it was known to exist abroad) is an important and grim milestone.
Bacteria have the ability to swap and share DNA, and thus may spread genes for antibiotic resistance. Because of this, in order to complete the puzzle of total antibiotic immunity, a bacterium merely needs to gather the various genes for resistance to each antibiotic from other bacteria. All of the required pieces are now present in the US, so it is only a matter of time before they all end up in a single ‘super-bug.’
Such a bacterium would be untreatable and thus extremely dangerous, and would usher in what is known as the ‘post-antibiotic era.’ However, it is important to note that the number of antibiotics is not fixed. While antibiotics are often not profitable and thus not frequently the focus of biological R&D efforts, there has been a recent push to discover new antibiotics using modern techniques in organic chemistry and molecular biology. These new antibiotics would hopefully fell the ‘super-bug’ once it comes into existence.
Many thanks to Daria Van Tyne and Christopher Gerry for their insight and comments on the story. Daria is a post-doctoral researcher at the Harvard Medical School. Christopher is a graduate student in the Department of Chemistry and Chemical Biology at Harvard University.
Managing Correspondent: Sam Dillavou
 (and picture) http://www.nytimes.com/2016/05/27/health/infection-raises-specter-of-superbugs-resistant-to-all-antibiotics.html