Disinfecting Action of Gaseous Ozone on OXA-48-Producing Klebsiella pneumoniae Biofilm In Vitro

Abstract

Klebsiella pneumoniae is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against K. pneumoniae biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding K. pneumoniae biofilm. A 24 h biofilm of K. pneumoniae formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of K. pneumoniae for 2.0 log10 CFU/cm2, followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative K. pneumoniae NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the K. pneumoniae biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.

Ozonated water in disinfection of hospital instrument table

“…Piletić et al ( 2022 ) also use an ATP luminometer to determine the efficiency of ozone, in the form of gas, on ceramic plates (in vitro) contaminated with Klebsiella pneumoniae and showed that ozone caused a significant reduction in biofilm. Recently, in the COVID-19 pandemic context, Mascarenhas et al ( 2022 ) used an ozonated water spray (0.7–0.9 ppm O 3 ) to disinfect the garments and accessories of a hundred volunteers.…”

“…In a short report (Breidablik et al 2020), the same researchers showed that ozonated water together with a regular soap-and-water hand wash may be more effective than alcohol for the removal of bacteria from artificially contaminated hands. Piletić et al (2022) also use an ATP luminometer to determine the efficiency of ozone, in the form of gas, on ceramic plates (in vitro) contaminated with Klebsiella pneumoniae and showed that ozone caused a significant reduction in biofilm. Recently, in the COVID-19 pandemic context, Mascarenhas et al (2022) used an ozonated water spray (0.7-0.9 ppm O 3 ) to disinfect the garments and accessories of a hundred volunteers.…”

Ozone disinfection efficiency against airborne microorganisms in hospital environment: a case study

“…Overall, our findings confirm high ozone efficacy against airborne bacteria in hospital settings reported earlier ( 25 ). However, its application as ambient disinfectant has certain limitations, as ozone gas it toxic to humans and can affect the respiratory system ( 41 ). The Croatian standards limit its concentration to 0.39 mg/m 3 over no more than 8 h a day ( 42 ).…”

Antibiofilm Activity of Different Washing Solutions against Biofilms in Cystic Fibrosis Patients' Nasal Cavities

“…strains, but found that ozone was unable to eradicate the pre-formed biofilm. Moreover, Piletić et al 28 reported that 25 ppm ozone gas could reduce biofilm but did not wholly eradicate the K. pneumoniae biofilm formed on ceramics.…”