Detrimental Effect of Ozone on Pathogenic Bacteria

Abstract

(1) Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated; (2) Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses; (3) Results: No reduction in the count colony was detected after O3 exposure compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%); (4) Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism.

Potent Activity of High Concentration Ozone Therapy Against Antibiotic-Resistant Bacteria

“…Conversely, when we investigated its metabolic capacity through resazurin, we found a significant reduction in values only for two strains, showing that ozone was able to interfere with cell viability of S. aureus (MRSA), which showed inhibition of about 99.6%, followed by P. aeruginosa XDR (29.2%). Curiously, in a recent study using the same strains, we have shown that ozone at low concentrations did not interfere with bacterial growth, but it could significantly inhibit cell viability [102]. Interestingly, reference strains (ATCC) from all species were less susceptible to ozone treatment.…”

Ozone treatment inactivates common bacteria and fungi associated with selected crop seeds and ornamental bulbs

“…This difference might be due to thicker layer of peptidoglycan, which provides physical strength to the bacterial cell wall, in Gram-positive Cmm than Gram-negative Pst . Several other reports also demonstrated that Gram-negative bacteria are more sensitive O 3 than Gram-positive ones ( Restaino et al, 1995 , Moore et al, 2000 , Zuma et al, 2009 , Rangel et al, 2022 ). Similarly, the fact that O 3 in gaseous form did not show any effect against fungal pathogens Fol and Forl in non-soaked tomato seeds at the tested duration and concentration may be due to the thicker cell wall structure of the fungi.…”

Potent Activity of a High Concentration of Chemical Ozone against Antibiotic-Resistant Bacteria

“…Conversely, when we investigated its metabolic capacity through resazurin, we found a significant reduction in values only for two strains, showing that ozone was able to interfere with the cell viability of S. aureus (MRSA), which showed inhibition of about 99.6%, followed by P. aeruginosa XDR (29.2%). Curiously, in a recent study using the same strains, we showed that ozone at low concentrations did not interfere with bacterial growth, but it could significantly inhibit cell viability [51]. Interestingly, all species' reference strains (ATCC) were less susceptible to ozone treatment.…”

“…For example, ozone gas in the concentration of 25 ppm caused a significant reduction in the number of viable bacteria and the total biomass of K. pneumoniae biofilm [48]. Furthermore, ozone seems to be very effective against planktonic bacteria, which are susceptible to ozone action and are often significantly reduced or completely eradicated from the surfaces with smaller concentrations [49][50][51][52]. Currently, with the COVID-19 pandemic, ozone has been investigated as a possible preventive measure for the spread of infection [53], in hospital hy-giene for disinfecting rooms [54], in viability on different surfaces [55], and as a therapeutic option in the treatment of patients [24,56].…”