Bactericidal efficacy of low dose gaseous ozone against clinically relevant multidrug-resistant bacteria

Area of Science:

• Microbiology
• Environmental Science
• Infection Control

Background:

• Healthcare-associated infections (HAIs) are a major problem in hospitals, especially ICUs.
• Current disinfection methods are often manual, labor-intensive, and ineffective against multidrug-resistant (MDR) pathogens.
• There is a need for automated, hands-free disinfection strategies to combat persistent environmental contamination.

Purpose of the Study:

• To evaluate the bactericidal efficacy of low concentrations of gaseous ozone (5 ppm) against clinically relevant bacteria.
• To assess the impact of varying concentrations, contact times, temperatures, and environmental conditions on ozone's effectiveness.
• To determine ozone's activity against multidrug-resistant (MDR) bacterial strains.

Main Methods:

• Exposure of various bacteria, including MDR strains, to low-dose gaseous ozone (5 ppm).
• Testing under different conditions: varying ozone concentrations, contact times, temperatures, and humidity.
• Quantification of bacterial reduction using log10-fold changes.

Main Results:

• A 3 log10-fold reduction was observed for *Escherichia coli* and *Salmonella Typhimurium*.
• A 1-2 log10-fold reduction was observed for Group A *Streptococcus* and methicillin-resistant *Staphylococcus aureus* (MRSA).
• Ozone demonstrated dose-dependent bactericidal activity, effective against a broad range of Gram-positive and -negative MDR clinical isolates, with minimal impact from environmental conditions.

Conclusions:

• Low-dose gaseous ozone is a potent, versatile, and hands-free disinfectant.
• It shows significant potential for use in healthcare environments to reduce pathogen contamination.
• Further research is required to establish safety and efficacy guidelines for occupied spaces and explore synergistic applications.