In vitro nano‑emodin-associated exosome‑mediated aPDT against Acinetobacter baumannii.

Area of Science:

• Biomedical Engineering
• Microbiology
• Drug Delivery Systems

Background:

• Multidrug-resistant (MDR) Acinetobacter baumannii biofilms pose significant challenges in treating burn wounds.
• Developing novel therapeutic strategies against resistant bacterial strains is crucial for effective wound management.

Purpose of the Study:

• To evaluate the antibacterial and antibiofilm efficacy of nano-emodin exosomes (NE-Exos) combined with antimicrobial photodynamic therapy (aPDT) against Acinetobacter baumannii.
• To assess the performance of NE-Exos against standard and clinical isolates, including MDR and extensively drug-resistant (XDR) strains.

Main Methods:

• Evaluated Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and biofilm inhibition/eradication concentrations (MBIC, MBEC).
• Assessed nano-emodin release kinetics at different pH levels and measured hemolysis.
• Quantified the downregulation of biofilm-associated genes (abaI, bap) using NE-Exos with aPDT.

Main Results:

• NE-Exos demonstrated significant antibacterial and antibiofilm activity, outperforming nano-emodin alone, especially against MDR isolates.
• Nano-emodin release from NE-Exos was pH-dependent, with higher release at acidic pH (5.5), and exhibited minimal hemolysis.
• Combined NE-Exos and aPDT markedly downregulated abaI and bap gene expression, reducing biofilm formation.

Conclusions:

• NE-Exos combined with aPDT represent a potent in vitro approach against Acinetobacter baumannii biofilms.
• Exosomes primarily function as carriers for nano-emodin, contributing to the observed antimicrobial effects.
• Further research is needed to address limitations, such as the lack of direct quantification of nano-emodin encapsulation.