tl;dr: researchers used Structure-Based Drug Design to derive a new antibiotic from florfenicol which shows effectiveness against a number of antibiotic-resistant bacteria.
Structure-based drug design (SBDD) aims to design small-molecule ligands that bind with high affinity and specificity to pre-determined protein targets.
What’s interesting about this one is that they were trying to optimize binding at the site in the bacterial ribosome where florfenicol is known to bind, and indeed improved it, but in doing so appear to have stumbled upon an additional mode of action, by binding to a protein called arcB which is critical for aspects of arginine metabolism in many bacteria, arginine metabolism being very important for many normal cell functions. Arginine metabolism may play a role in maintenance of the bacterial cell membrane, and the bacteria did seem to be leaking their contents into the environment at a higher rate after application of the compound, among other effects.
My interpretation here, but the fact that this compound is active at both the same site as the compound it was based on, and an entirely different site which also happens to be critical to bacterial metabolism, makes it very interesting from a drug resistance perspective, because a given strain of bacteria would potentially need more adaptations to successfully resist the drug than to resist a drug which is only active at one site.