In vitro assessment of an antimicrobial peptide against Acinetobacter baumannii persister cells

Abstract

Abstract The rise of multidrug-resistant and persister cell populations of Acinetobacter baumannii ( A. baumannii ) poses a significant threat in healthcare settings, highlighting the need for novel therapeutic strategies. This study investigates a specifically designed antimicrobial peptide and its potential activity against this pathogen. Using advanced bioinformatics, a 20-amino acid antimicrobial peptide was designed and synthesized. The peptide’s efficacy was evaluated in vitro through MIC assays against A. baumannii , along with assessments of its effects on persister cells, biofilm formation, and gene expression (pmrB and lasI) using quantitative PCR. The designed peptide exhibited a potent MIC value of 64 µg/mL, reducing persister cell populations of A. baumannii by 75% within 24 h (p < 0.0001). It significantly inhibited biofilm formation, with OD reductions of up to 5.4 log at 64 µg/mL (p < 0.0001). Real-time PCR analysis revealed a 6.2-fold upregulation of pmrB and 3.7-fold upregulation of lasI after 24 h (p < 0.0001), indicating bacterial adaptive responses. The antimicrobial peptide demonstrated strong antibacterial and antibiofilm activity against A. baumannii , though with moderate cytotoxicity (8–17% reduction in cell viability). These findings suggest a promising avenue for developing novel antimicrobial strategies.