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

## TL;DR

A new antimicrobial peptide was tested in the lab and showed strong effectiveness against a dangerous antibiotic-resistant bacteria called Acinetobacter baumannii, including reducing its persistent cells and biofilm formation.

## Contribution

A novel antimicrobial peptide was designed and shown to effectively target A. baumannii persister cells and biofilms with significant in vitro efficacy.

## Key findings

- The antimicrobial peptide reduced A. baumannii persister cell populations by 75% within 24 hours.
- The peptide inhibited biofilm formation with up to 5.4 log reduction in optical density at 64 µg/mL.
- The peptide caused significant upregulation of pmrB and lasI genes in A. baumannii, indicating bacterial adaptive responses.

## 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.