A short antimicrobial peptides family demonstrates efficacy to infection via a multimodal mechanism of action.

The escalating threat posed by multidrug-resistant (MDR) Gram-negative "superbugs" has intensified. Short antimicrobial peptides (SAMPs) have emerged as promising therapeutics with sustained potency and cost-effectiveness against drug-resistant infections. Here, we report a family of 15-residue SAMPs derived through modifying related amino acids of Kassporin-KS1 (FA), utilizing database-filtering technology to identify the most probable structural parameters related to Gram-negative bacteria. Most SAMPs exhibit sub-μM antimicrobial activity with reliable stability and low toxicity. Notably, KR and RK demonstrate significant efficacy in combating biofilms and sepsis infections in vivo. Furthermore, the acquisition of resistance by strains to SAMPs was not observed, primarily due to the multimodal antimicrobial mechanisms of SAMPs. We revealed that the multimodal mechanisms of SAMPs encompass unregulated membrane destabilization, induction of apoptotic-like death pathway, and interference with normal physiological processes. Overall, the rational design strategies proposed herein can be implemented to develop potent antimicrobial agents targeting MDR bacteria.