Major article
Ozone gas is an effective and practical antibacterial agent

https://doi.org/10.1016/j.ajic.2007.10.021Get rights and content

Background

Bacterial infections continue to pose a threat to health in many institutional and communal settings, and epidemics are frequent. Current control measures are clearly inadequate; thus, there is a need for a simple, effective, and safe way to decontaminate surfaces.

Methods

We evaluated the efficacy of a portable ozone-generating machine, equipped with a catalytic converter and an accessory humidifier, to inactivate 15 different species of medically important bacteria.

Results

An ozone dosage of 25 ppm for 20 minutes, with a short burst of humidity in excess of 90% relative humidity, was able to inactivate more than 3 log10 colony-forming units of most of the bacteria, including Acinetobacter baumannii, Clostridium difficile, and methicillin-resistant Staphylococcus aureus, in both in a laboratory test system and simulated field conditions. In many cases, complete eradication was achieved. Dried and wet samples were equally vulnerable to the ozone. Inactivation of bacterial samples dried onto soft surfaces (eg, fabric, cotton, filter paper) were comparable with that observed for samples on plastic.

Conclusions

The ozone generator can provide a valuable decontamination tool for the removal of bacteria in many institutional and communal settings, including hospitals and other health care institutions.

Section snippets

Equipment

The laboratory test chamber was a molded polycarbonate box (4.47 ft3 volume) with a transparent plastic front window that could be lifted to allow access to samples. Within the test chamber was a small ozone generator (Treated Air Systems, Surrey, BC, Canada). Relative humidity and temperature were recorded by a portable hygrometer (cat no. 12777-834; VWR Scientific, Ontario, Canada). Humidity was provided in the form of a deionized sterile water mist using a spray bottle.

The ozone generator

Results

All 15 bacteria were initially evaluated for susceptibility to standard ozone doses in the laboratory test system. Replicate 100-uL samples of the bacterial suspensions at the 2.0 McFarland standard (6 × 108 cfu/mL in PBS) were dried onto sterile plastic trays in a biosafety cabinet and then exposed to a standard ozone dosage of 25 ppm for 20 minutes. Preliminary tests had demonstrated that the minimum requirements for efficient inactivation of bacteria were an ozone dosage of 20 ppm for 20

Discussion

Nosocomial infection is considered to more than double the mortality and morbidity risks of any hospitalized patient. An estimated 1 in 10 patients admitted to the hospital will acquire an infection after admission, resulting in substantial morbidity and economic cost to the health care system.18 Patients with hospital-acquired infections (HAIs) stay longer, require additional diagnostic and therapeutic procedures, and are at increased risk for other medical complications.18 Approximately 1/3

Conclusion

Our findings demonstrate that ozone at 25 ppm and RH 90% is bactericidal (> 3 log10 reduction in bacterial cfu/mL) to strains of bacteria that commonly cause nosocomial infection, and the bactericidal effect was accomplished with a short exposure (20 minutes). Thanks to the highly efficient scrubber system built into the generator, gas removal after exposure is fast and efficient. Because it is used in rooms that are sealed off for the duration of treatment, there is no danger of toxicity due

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