Effect of hyperbaric air on endotoxin from Bacteroides fragilis strains

COVID-19 infection prevention and control management during hyperbaric oxygen therapy: a best practice implementation project

OBJECTIVE

This implementation project compared standard operating procedures, accepted preventive measures, and disinfection procedures between the initial stage of the COVID-19 pandemic (first wave: March 15 to May 31, 2020) and the later stages of the pandemic (second and third waves: September 1, 2020 to January 31, 2021).

INTRODUCTION

This project sought to improve compliance with international evidence-based guidelines and clinical standards for the prevention and control of COVID-19 infection during hyperbaric oxygen therapy taking into account the conditions of the local hospital.

METHODS

Guided by the JBI evidence implementation framework, seven evidence-based audit criteria were developed for the prevention and control of COVID-19 infection during hyperbaric oxygen therapy. A questionnaire was used to measure compliance in baseline and follow-up audits.

RESULTS

Differences between the baseline and follow-up audits were noted for criteria 6 and 7. Criterion 6 increased from 0% to 100% as the hyperbaric facility was equipped with certified ultraviolet-C radiation for air disinfection during the later period, but this equipment was not available in the initial period of the pandemic. Criterion 7 dropped from 100% in the baseline audit to 0% in the follow-up audit because of a significant increase in the operational burden of the treatment capacity of the facility, which made it impossible to comply with the recommended distancing between patients.

CONCLUSIONS

Differences were found in preventive measures, disinfection procedures, work organization, and approach to care strategy. The project objectives were met and the implementation strategies proved effective. Larger sample sizes would need be needed to confirm the reproducibility of the results.

Impact of vitamin A transport and storage on intestinal retinoid homeostasis and functions

Lecithin:retinol acyltransferase and retinol-binding protein enable vitamin A (VA) storage and transport, respectively, maintaining tissue homeostasis of retinoids (VA derivatives). The precarious VA status of the lecithin:retinol acyltransferase-deficient (Lrat-/-) retinol-binding protein-deficient (Rbp-/-) mice rapidly deteriorates upon dietary VA restriction, leading to signs of severe vitamin A deficiency (VAD). As retinoids impact gut morphology and functions, VAD is often linked to intestinal pathological conditions and microbial dysbiosis. Thus, we investigated the contribution of VA storage and transport to intestinal retinoid homeostasis and functionalities. We showed the occurrence of intestinal VAD in Lrat-/-Rbp-/- mice, demonstrating the critical role of both pathways in preserving gut retinoid homeostasis. Moreover, in the mutant colon, VAD resulted in a compromised intestinal barrier as manifested by reduced mucins and antimicrobial defense, leaky gut, increased inflammation and oxidative stress, and altered mucosal immunocytokine profiles. These perturbations were accompanied by fecal dysbiosis, revealing that the VA status (sufficient vs. deficient), rather than the amount of dietary VA per se, is likely a major initial discriminant of the intestinal microbiome. Our data also pointed to a specific fecal taxonomic profile and distinct microbial functionalities associated with VAD. Overall, our findings revealed the suitability of the Lrat-/-Rbp-/- mice as a model to study intestinal dysfunctions and dysbiosis promoted by changes in tissue retinoid homeostasis induced by the host VA status and/or intake.

Experimental use of flow cytometry to detect bacteria viability after hyperbaric oxygen exposure: Work in progress report

INTRODUCTION

Hyperbaric oxygen treatment (HBOT), based on inhaling pure oxygen under elevated ambient pressure, is used as adjuvant intervention to promote healing in infected wounds. Despite extensive clinical evidence of beneficial effects of HBOT in soft tissue infections the mechanism of action remains to be elucidated. The aim of this study was to evaluate the use of flow cytometry as a novel method to assess the viability of pathogenic bacteria after hyperbaric oxygen (HBO) exposure.

METHODS

Bacterial strains associated with soft tissues infections: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus were exposed to oxygen at 2.8 atmospheres absolute (atm abs) (283.6 kPa) pressure for 45, 90, or 120 min, then stained with propidium iodide and thiazole orange and analysed by flow cytometry.

RESULTS

Escherichia coli and Staphylococcus aureus showed no change in viability, nor morphology, the viability of Pseudomonas aeruginosa reduced in a dose-dependent manner and Klebsiella pneumoniae also showed dye uptake after HBO.

CONCLUSIONS

These initial results, indicate diverse sensitivity of bacteria to HBO, and suggest that flow cytometry can be used to monitor viability and morphological changes triggered by HBO exposure in bacteria.

The role of intestinal microbiota in the pathogenesis of colorectal carcinoma

The symbiotic relationship between intestinal microbiota and the host is a major mechanism of prevention against the development of chronic and metabolic diseases. The intestinal microbiota provides several physiological functions of the organism from the creation of a natural functional barrier with a subsequent immunostimulatory activity up to affecting the energy metabolism of the host. Disruption of physiological intestinal microbiota is reported as one of the major etiological factors of initiation and progression of colorectal carcinoma (CRC). Chronic low-grade inflammation is associated with the development of CRC, through the production of inflammatory cytokines and reactive oxygen species. CRC occurs in association with high-protein and high-fat diets in combination with low-fiber intake. The problem of intestinal dysbiosis and oncological diseases is a multidisciplinary problem and it is necessary to focus on several fields of medicine such as public health, clinical pharmacology, and internal medicine. The aim of this review is describing the role of gut dysbiosis in pathogenesis of colorectal carcinoma.

Antibiotic susceptibility and production of endotoxin by Ochrobactrum anthropi isolated from environment and from patients with cystic fibrosis

The aim of this work was to compare production of endotoxin and to determine susceptibility to antibiotics in two groups of specimens-wild-type strains Ochrobactrum anthropi isolated from the environment and the strains isolated from patients with cystic fibrosis. The determination of the endotoxin produced by the test strains was carried on by using a limulus amebocyte lysate test (LAL test). Determination of ATB sensitivity was accomplished by means of a broth dilution method in a microtiter plate (MIC). No significant difference was found between the group of ochrobacters isolated from the environment and the group of ochrobacters isolated from cystic fibrosis patients. Antibiotic sensitivity testing has indicated that the resistance to tigecycline, trimethoprim/sulfamethoxazole, and gentamicin was slightly higher in strains isolated from cystic fibrosis patients in comparison with strains isolated from the environment. In general, most of the test strains were sensitive to most of the antibiotics tested. Significant resistance has been demonstrated for cefotaxime. Resistance was also found for gentamicin in strains number 4 and 7. The MIC was equal to the breakpoint for this antibiotic (8000 mg/L).