The Antimicrobial Peptide Octopromycin Suppresses Biofilm Formation and Quorum Sensing in Acinetobacter baumannii

Abstract

<i>Acinetobacter baumannii</i> is an opportunistic bacterial pathogen that causes severe infections in immunocompromised individuals. <i>A. baumannii</i> forms biofilm and produces extracellular matrix, which supports bacteria to survive under harsh conditions and be resistant to antibacterial treatments. In the present study, we investigated the biofilm and quorum-sensing inhibitory effects of antimicrobial peptide, octopromycin in <i>A. baumannii</i>. Field emission-scanning electron microscopy results clearly showed significantly reduced biofilm mass and caused a collapse in biofilm architecture at the minimum inhibitory concentration (50 µg/mL) and minimum bactericidal concentration (200 µg/mL) of octopromycin. Antibiotic-resistant persister cells of <i>A. baumannii</i> were successfully killed by octopromycin treatment, and it inhibited violacein production in <i>Chromobacterium violaceum</i> in a concentration-dependent manner. Octopromycin also inhibited alginate production, surface movements (swarming and swimming), and twitching motility of <i>A. baumannnii</i>, confirming its anti-quorum-sensing activity. Multiple metabolic pathways, two-component regulation systems, quorum-sensing, and antibiotic synthesis-related pathways in <i>A. baumannii</i> biofilms were strongly affected by octopromycin treatment. The collective findings indicate that the antibacterial peptide octopromycin may control <i>A. baumannii</i> biofilms through multi-target interactions. Octopromycin could be a desirable therapeutic option for the prevention and control of <i>A. baumannii</i> infections.