Jelleine‑IMembrane Interaction-related BiologicalProperties and Antimicrobial Activity against MDR, XDR, and PDR-Acinetobacter baumannii Clinical Isolates

Emerging bacterial infections pose a serious threat to human health. Acinetobacter baumannii is a particular concern due to its antimicrobial resistance phenotypes, especially to carbapenems. In this context, antimicrobial peptides appear as a promising class. Jelleine-I is a peptide identified from the royal jelly from Apis mellifera bee, which has demonstrated significant antibacterial effects against various microorganisms. This study aimed to characterize the activity of jelleine-I against clinical isolates of A. baumannii resistant to carbapenems (CRAB) and with different resistance phenotypes, in addition to investigating the peptide–membrane interaction in biomimetic media. Microbiological assays with jelleine-I performed against A. baumannii with MIC values of 8–16 μM were observed. Biophysical studies on the bacterial mimetic membrane show a possible disruption of the organization of the phospholipid bilayer. The significant affinity promoted by entropic and enthalpic contributions suggests that the main antimicrobial action occurs on the bacterial membrane. In addition, the negligible hemolytic activity and toxicity against VERO and HaCaT cells reveal jelleine-I as a potential novel antimicrobial agent, especially against microorganisms that exhibit high and diverse antimicrobial resistance, such as A. baumannii.