Gaseous ozone treatment inactivates Listeria innocua in vitro

Evaluation of antibacterial oxygen/ozone mixture in vitro activity on bacteria isolated from cervico-vaginal mucus of cows with acute metritis

Ozone is an oxidating gas showing a strong microbicidal activity on bacteria, fungi, viruses and protozoa. The aim of this study was to test the in vitro bacteriocidal action of an Ozone/Oxygen gas mixture on bacteria isolated from the cervico-vaginal mucus of cows affected by acute metritis. A pilot study was initially carried out on reference strains (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Mycoplasma bovigenitalium ATCC 19852) that were tested with three different treatments: a control positive baseline group (B-group) was incubated without gas treatment, a control positive oxygen group (O₂-group) was treated with pure oxygen 100%, and the treated group (T-group) was exposed to a gaseous constant flow of an Ozone/Oxygen mixture, at 50, 35, 20 μg Ozone/ml and for 5, 3 and 1 min for every different Ozone concentration. In both positive control groups, the number of colony forming units (CFU) per ml was higher than 300 CFU/ml (E. coli and S. aureus) and higher than 30 CFU/ml for M. bovigenitalium, after incubation. The T-groups showed a minimal bacterial growth equal to or lower than 1 CFU/ml per plate. Based on the results of the pilot study, a second phase was performed on bacteria isolated from the cervico-vaginal mucus (Klebsiella pneumoniae, Enterobacter agglomerans, E. coli, Proteus mirabilis and M. bovigenitalium) using the lower concentration of 20 μg/ml of Ozone for the minimum exposure time of 1 min. The E. coli and S. aureus reference strains and the clinical isolates (K. pneumoniae, E. agglomerans, E. coli, P. mirabilis) were incubated at 37 °C for 48 h and the colonies were manually counted at 24 h and 48 h following inoculation. The cultures of M. bovigenitalium (both ATCC and clinical isolate) were incubated in a jar with modified atmosphere conditions with 5% CO₂ at 37 °C for 4-7 days and colony counting was performed. The second phase showed a low number of CFUs (equal to or less than 7 CFU/ml) for the clinical isolates K. pneumoniae, E. agglomerans, E. coli and P. mirabilis, and, of note, for M. bovigenitalium, both ATCC and clinical isolate, the growth was completely inhibited. Ozone was demonstrated to have a bacteriocidal activity. This study encourages further research of in vivo application of low doses of gaseous Ozone for the treatment of metritis in cows by using minimal exposure times.

Pulmonary effects of ozone therapy at different doses combined with antibioticotherapy in experimental sepsis model

Purpose

This experimental sepsis model created with Escherichia coli aimed to investigate the histopathological effects of two different doses of ozone combined with antibiotherapy on lung tissue.

Methods

Rats were divided into 5 groups. Then sepsis was induced intraperitoneally in the first 4 groups. The 1^st group was treated with cefepime, the 2^nd and 3^rd groups were treated with cefepime combined with ozone at a dose of 0.6 mg/kg and 1.1 mg/kg. Lung tissue sections were stained with hematoxylin-eosin and assessed under light microscope and scored between 0-4 in terms of histopathological findings.

Results

In the comparisons between Group 1 and Group 4 in terms of cellular damage (p=0.030), inflammation (p=0.000) and overall score (p=0.007), statistically significant positive effects were observed in favor of Group 1. In the comparisons of Groups 2 and 3 with Group 4, only positive effects were observed in terms of inflammation (p=0.020, p=0.012, respectively).

Conclusion

Although negative histopathological effects of ozone on tissue injury were detected, it was noteworthy that the increase in the ozone dose reduced the number of damaged parameters.

The microbial killing capacity of aqueous and gaseous ozone on different surfaces contaminated with dairy cattle manure

A high reactivity and leaving no harmful residues make ozone an effective disinfectant for farm hygiene and biosecurity. Our objectives were therefore to (1) characterize the killing capacity of aqueous and gaseous ozone at different operational conditions on dairy cattle manure-based pathogens (MBP) contaminated different surfaces (plastic, metal, nylon, rubber, and wood); (2) determine the effect of microbial load on the killing capacity of aqueous ozone. In a crossover design, 14 strips of each material were randomly assigned into 3 groups, treatment (n = 6), positive-control (n = 6), and negative-control (n = 2). The strips were soaked in dairy cattle manure with an inoculum level of 10⁷–10⁸ for 60 minutes. The treatment strips were exposed to aqueous ozone of 2, 4, and 9 ppm and gaseous ozone of 1and 9 ppm for 2, 4, and 8 minutes exposure. 3M™ Petrifilm™ rapid aerobic count plate and plate reader were used for bacterial culture. On smooth surfaces, plastic and metal, aqueous ozone at 4 ppm reduced MBP to a safe level (≥5-log₁₀) within 2 minutes (6.1 and 5.1-log₁₀, respectively). However, gaseous ozone at 9 ppm for 4 minutes inactivated 3.3-log₁₀ of MBP. Aqueous ozone of 9 ppm is sufficient to reduce MBP to a safe level, 6.0 and 5.4- log_10, on nylon and rubber surfaces within 2 and 8 minutes, respectively. On complex surfaces, wood, both aqueous and gaseous ozone at up to 9 ppm were unable to reduce MBP to a safe level (3.6 and 0.8-log₁₀, respectively). The bacterial load was a strong predictor for reduction in MBP (P<0.0001, R² = 0.72). We conclude that aqueous ozone of 4 and 9 ppm for 2 minutes may provide an efficient method to reduce MBP to a safe level on smooth and moderately rough surfaces, respectively. However, ozone alone may not an adequate means of controlling MBP on complex surfaces.

Modelling the Ozone-Based Treatments for Inactivation of Microorganisms

The paper presents the development of a model for ozone treatment in a dynamic bed of different microorganisms (Bacillus subtilis, B. cereus, B. pumilus, Escherichia coli, Pseudomonas fluorescens, Aspergillus niger, Eupenicillium cinnamopurpureum) on a heterogeneous matrix (juniper berries, cardamom seeds) initially treated with numerous ozone doses during various contact times was studied. Taking into account various microorganism susceptibility to ozone, it was of great importance to develop a sufficiently effective ozone dose to preserve food products using different strains based on the microbial model. For this purpose, we have chosen the Weibull model to describe the survival curves of different microorganisms. Based on the results of microorganism survival modelling after ozone treatment and considering the least susceptible strains to ozone, we selected the critical ones. Among tested strains, those from genus Bacillus were recognized as the most critical strains. In particular, B. subtilis and B. pumilus possessed the highest resistance to ozone treatment because the time needed to achieve the lowest level of its survival was the longest (up to 17.04 min and 16.89 min for B. pumilus reduction on juniper berry and cardamom seed matrix, respectively). Ozone treatment allow inactivate microorganisms to achieving lower survival rates by ozone dose (20.0 g O₃/m³ O₂, with a flow rate of 0.4 L/min) and contact time (up to 20 min). The results demonstrated that a linear correlation between parameters p and k in Weibull distribution, providing an opportunity to calculate a fitted equation of the process.

Ozonated saline shows activity against planktonic and biofilm growing Staphylococcus aureus in vitro: a potential irrigant for infected wounds

Infections associated with deep wounds require extensive surgical and medical care. New adjunctive treatments are required to aid in the eradication of the bacterial biofilms found on infected wounds and, in particular, any underlying hardware. Ozone has been used as a safe and efficient disinfectant in water treatment plants for many years. The purpose of this study is to investigate the anti-biofilm potential of ozonated saline against biofilms of Staphylococcus aureus, a microorganism commonly implicated in wound infections. A custom-made bacterial biofilm bioreactor was used to grow S. aureus biofilms on discs of medical grade titanium alloy. An ozone generator was connected in-line and biofilms and planktonic bacteria were exposed to ozone in saline. Cytotoxicity was assessed against primary ovine osteoblasts in the same system. In tests against planktonic S. aureus, a 99% reduction in bacterial numbers was detected within 15 minutes of exposure. S. aureus biofilms were significantly more resistant to ozone, although complete eradication of the biofilm was eventually achieved within 5 hours. Ozonated saline was not found to be cytotoxic to primary ovine osteoblasts. Ozonated saline may be suitable as an adjuvant therapy to treat patients as an instillation fluid for wound irrigation and sterilisation.

Effect of low-dose gaseous ozone on pathogenic bacteria

Background

Treatment of chronically infected wounds is a challenge, and bacterial environmental contamination is a growing issue in infection control. Ozone may have a role in these situations. The objective of this study was to determine whether a low dose of gaseous ozone/oxygen mixture eliminates pathogenic bacteria cultivated in Petri dishes.

Methods

A pilot study with 6 bacterial strains was made using different concentrations of ozone in an ozone-oxygen mixture to determine a minimally effective dose that completely eliminated bacterial growth. The small and apparently bactericidal gaseous dose of 20 μg/mL ozone/oxygen (1:99) mixture, applied for 5min under atmospheric pressure was selected. In the 2^nd phase, eight bacterial strains with well characterized resistance patterns were evaluated in vitro using agar-blood in adapted Petri dishes (10⁵ bacteria/dish). The cultures were divided into 3 groups: 1- ozone-oxygen gaseous mixture containing 20 μg of O₃/mL for 5 min; 2- 100% oxygen for 5 min; 3- baseline: no gas was used.

Results

The selected ozone dose was applied to the following eight strains: Escherichia coli, oxacillin-resistant Staphylococcus aureus, oxacillin-susceptible Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, carbapenem-resistant Acinetobacter baumannii, Acinetobacter baumannii susceptible only to carbapenems, and Pseudomonas aeruginosa susceptible to imipenem and meropenem. All isolates were completely inhibited by the ozone-oxygen mixture while growth occurred in the other 2 groups.

Conclusion

A single topical application by nebulization of a low ozone dose completely inhibited the growth of all potentially pathogenic bacterial strains with known resistance to antimicrobial agents.

Safety and quality assessment during the ozonation of cloudy apple juice

Traditionally, ozone processing within the food industry has focused on solid foods by either gaseous treatment or washing with ozonized water. However, with the FDA's approval of ozone as a direct additive to food, the potential for liquid applications has emerged. This study investigates the effect of ozone processing on microbial inactivation (E. coli ATCC 25922 and NCTC 12900) and quality parameters (color, phenolic content) of cloudy apple juice. Apple juice samples were ozonated at room temperature (20 ± 1.5 °C) with a generated ozone concentration of 0.048 mg O(3) at a constant flow rate of 0.12 L/min and treatment time of 0 to 10 min. E. coli inactivation kinetics in apple juice were described quantitatively by using the Shoulder log-linear and the Weibull model. Ozone treatment of E. coli in apple juice demonstrate that a desired 5 log reduction can be achieved within 5 min. Apple juice color (L*, a*, and b*) and total phenols were significantly affected by ozone concentration and treatment time.

Evaluation of the effects of ozone therapy in the treatment of intra-abdominal infection in rats

INTRODUCTION

The antibacterial effect of ozone (O(3)) has been described in the extant literature, but the role of O(3) therapy in the treatment of certain types of infection remains controversial.

OBJECTIVES

To evaluate the effect of intraperitoneal (i.p.) O(3) application in a cecal ligation/puncture rat model on interleukins (IL-6, IL-10) and cytokine-induced neutrophil chemoattractant (CINC)-1 serum levels, acute lung injury and survival rates.

METHODS

FOUR ANIMAL GROUPS WERE USED FOR THE STUDY: a) the SHAM group underwent laparotomy; b) the cecal ligation/puncture group underwent cecal ligation/puncture procedures; and c) the CLP+O(2) and CLP+O(3) groups underwent CLP+ corresponding gas mixture infusions (i.p.) throughout the observation period. IL-6, CINC-1 and IL-10 concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Acute lung injury was evaluated with the Evans blue dye lung leakage method and by lung histology. P<0.05 was considered significant.

RESULTS

CINC-1 was at the lowest level in the SHAM group and was lower for the CLP+O(3) group vs. the CLP+O(2) group and the cecal ligation/puncture group. IL-10 was lower for the SHAM group vs. the other three groups, which were similar compared to each other. IL-6 was lower for the SHAM group vs. all other groups, was lower for the CLP+O(3) or CLP+O(2) group vs. the cecal ligation/puncture group, and was similar for the CLP+O(3) group vs. the CLP+O(2) group. The lung histology score was lower for the SHAM group vs. the other groups. The Evans blue dye result was lower for the CLP+O(3) group vs. the CLP+O(2) group and the cecal ligation/puncture group but similar to that of the SHAM group. The survival rate for the CLP+O(3) group was lower than for the SHAM group and similar to that for the other 2 groups (CLP and CLP+O(2)).

CONCLUSION

Ozone therapy modulated the inflammatory response and acute lung injury in the cecal ligation/puncture infection model in rats, although there was no improvement on survival rates.