Although new antibiotics are discovered quite regularly it is unusual that a whole new mode of action is discovered. A compound called Hydramacin was described in a paper yesterday. The compound was discovered in the freshwater hydra, hence the name.
In a series of laboratory experiments hydramacin was shown to kill a wide range of both Gram-positive and Gram-negative bacteria. Hydramacin works by sticking to the bacterial surface, promoting the clumping of nearby bacteria, then disrupting the bacterial membrane.