Colistin is a very old antibacterial drug, which was taken out of use on patients because it had some really bad side effects — often worse than the infection it was trying to treat!

However, in the last 15 years, we have improved how we use colistin, and it has returned to clinical practice.

It was first isolated in 1949 from the nitrogen-fixing bacterium Bacillus polymyxa var. colistinus, hence the name ‘colistin’. For the same reason the class of antibiotics colistin belongs to are called ‘polymyxins’.

Colistin is now one of our most effective drugs in fighting infections that are resistant to more modern antibacterial drugs, including multiresistant “superbugs”.

Colistin-resistant bacteria emerged first in 2015 — leading to potentially untreatable infections. But so far, colistin-resistant bacteria have not caused any disease outbreak.