eDNA Inactivation and Biofilm Inhibition by the PolymericBiocide Polyhexamethylene Guanidine Hydrochloride (PHMG-Cl)

Area of Science:

• Microbiology
• Environmental Science
• Hospital Infection Control

Background:

• Disinfectants play a role in hospital resistome development and antibiotic resistance gene transfer.
• Understanding biocide-induced extracellular DNA (eDNA) release is crucial for controlling gene transfer and environmental retention.
• Hospital microbial populations are influenced by disinfectants, impacting antibiotic resistance.

Purpose of the Study:

• To investigate how different biocides affect eDNA release from biofilms of *Pseudomonas aeruginosa* and *Staphylococcus aureus*.
• To evaluate the contribution of biocides to the hospital resistome, including surface, water, and dust contaminants.
• To assess the efficacy of polyhexamethylene guanidine hydrochloride (PHMG-Cl) in preventing biofilm development and inactivating antibiotic resistance genes.

Main Methods:

• Exposure of mature biofilms of *P. aeruginosa* and *S. aureus* to four biocide groups: alcohols, hydrogen peroxide, quaternary ammonium compounds, and PHMG-Cl.
• Quantification of eDNA release following biocide treatment.
• Molecular docking assays to predict PHMG-Cl binding to DNA.
• Assessment of PHMG-Cl's ability to inactivate DNA on surfaces and antibiotic resistance gene eDNA from a *Klebsiella* strain.

Main Results:

• Most biocides, excluding PHMG-Cl and 70% ethanol, induced significant eDNA release.
• PHMG-Cl inhibited biofilm formation at 0.5% and 0.1% concentrations, potentially by forming DNA-PHMG-Cl complexes.
• PHMG-Cl demonstrated sustained DNA inactivation on surfaces for over 4 weeks and effectively inactivated antibiotic resistance gene eDNA.

Conclusions:

• PHMG-Cl shows promise as a novel surface-active agent to mitigate antibiotic resistance spread in hospitals.
• The study highlights the importance of selecting biocides that minimize eDNA release and resistome development.
• PHMG-Cl's ability to bind DNA and inactivate resistance genes offers a new strategy for infection control.