Polymyxin antibiotics are considered to be “last-resort” antibiotics due to their incredible efficacy, even against otherwise antibiotic-resistant bacteria. However, little was known about exactly how they work – until now. 
Researchers at the University of Basel, Switzerland, have discovered that these antibiotics crystallize the plasma membranes of bacteria.
This crystallization causes the fatty part of a lipopolysaccharide to form a hexagonal structure, which decreases the thickness of the plasma membrane, weakens it, and eventually makes it burst, causing the death of the cell. The lipopolysaccharide normally contributes to the structure and stability of the plasma membrane; if a bacteria is coded without these genes, it will die quickly due to the plasma membrane bursting due to lack of stability. Similarly, the membrane loses much of its structural integrity and collapses when the antibiotic crystallizes it.
This breakthrough is important due to the growing problem of antibiotic resistance: antibiotics are simply less effective than they used to be, as bacteria evolve so that antibiotics no longer kill them. As a result, new antibiotics must be found to maintain efficacy. Now that we know more about why polymyxin antibiotics work, new derivatives can be found to improve public health.
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