Antimicrobial peptide CEC-TY1: a potential antibacterial drug against carbapenem-resistant <i>Klebsiella pneumoniae</i>

Carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) infections in hospitals and the issues arising from their rapid spread have become significant public health challenges. Therefore, a new class of effective and safe antibacterial drugs is urgently required. In this study, we identified an antimicrobial peptide in the cecropin family, cecropin-TY1 (CEC-TY1), from the salivary glands of the horsefly. CEC-TY1 showed significant antibacterial activity against gram-negative bacteria, at concentrations up to 100 μg/mL, with no observed cytotoxicity or hemolytic activity against cells. Moreover, CEC-TY1 protected mice from lethal infections of CRKP <i>in vivo</i>, improving the survival rate of the infected mice. This peptide also alleviated excessive and harmful inflammatory responses by inhibiting the production of interleukin (IL)-6, tumor necrosis factor-α, and IL-1β.IMPORTANCEAntimicrobial peptides are a promising alternative to antibiotics in the current antibiotic resistance crisis. Specifically, the antimicrobial peptide cecropin-TY1 (CEC-TY1), identified in the salivary glands of horseflies, showed significant antibacterial activity against carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP), both <i>in vitro</i> and <i>in vivo</i>. CEC-TY1 also has selective toxicity and low hemolytic activity and is therefore a potential therapeutic agent for acute CRKP infection.