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.

A simple and reliable refractometric method to determine the total solids concentration of the cervico-vaginal bovine mucus samples

Cervico-vaginal mucus (CVM) is a viscoelastic substance continuously produced by secretory cells of the endocervix and the vagina of cows. Its physicochemical composition varies depending on the hormonal status of the estrous cycle. In veterinary medicine refractometry is a widely diffused technique to determine total solids (TS) content of biological samples, but there are not published data of CVM total solids from refractometric measures. Refractometric TS determination contributes to the qualitative constituents analysis of CVM, additionally it is an easier and more inexpensive technique than gravimetric TS determination. The main goal of the present paper was to validate a refractometric method to estimate TS concentration of the soluble fraction of CVM samples. Samples were collected from seventy-three Holando Argentino cows of Santa Fe province farms in Argentina. Cows were classified in three experimental groups: healthy, subclinical (SE) and clinical endometritis (CE) group. To achieve a solubilisation protocol for CVM samples, four Triton™ X-100 concentrations were tested. Refractive index (RI) and gravimetric total solid (gTS) concentration of solubilised samples were determined for the three experimental groups. A mathematical equation was determined with the experimental data from the healthy group, in order to obtain calculated total solid concentration (cTS) from refractivity (R) values. To validate the RI method for CVM samples, cTS concentrations were compared with gTS concentrations from endometritis group samples. Triton™ X-100 0.01% (V/V) improved CVM samples handling and did not change physicochemical parameters (gTS, Na⁺ and K⁺ concentration, and RI values). The linear regression equation obtained was: cTS (g/dL) = (R - 0.67)/16.2, r² = 0.91. Correlation between gTS and cTS concentration was: r = 0.97 for SE group and r = 0.97 for CE group. The homogenization protocol allowed the measurement of physicochemical parameters without altering their values. A high correlation coefficient between cTS and gTS postulates refractometry as an accurate method to determine TS concentration for solubilised CVM samples.

Significance of cervico-vaginal microbes in bovine reproduction and pheromone production - A hypothetical review

The vaginal microbiota has been studied in animal reproduction and fertility, in particular little information of vaginal microbes in reference to bovine reproduction and pheromone production is known. The vaginal mucosa in healthy cow is colonized by an equilibrated and dynamic composition of aerobic, facultative anaerobic and obligate anaerobic microbes. Cervico-vaginal mucus (CVM) composition, viscosity and volume vary with the cyclicity and health status of the reproductive tract. In addition, CVM contains pheromones, volatile compounds, and proteins that attract males for coitus. Commensal microbiota plays a key role in protection of the genital tract from pathogenic microbes by competition effect. In the bovine species, the microbial composition, its abundance and diversity in the female gut, vagina, urine, saliva, and feces, and the associated chemical communication remains poorly documented. The impact of microbes in the reproductive tract of cow, buffalo and certain mammals are discussed in this review. Since the microbial population diversity of CVM is modified during estrus phase it presumes that it may have a role for pheromone production in conspecific. Herein, we would like to critically discuss the current state of knowledge on microbially produced signals in animals and the role of genital and CVM microbiota in estrous cycle and pregnancy.

Cervico-vaginal mucus (CVM) - an accessible source of immunologically informative biomolecules

Cervico-vaginal mucus (CVM), the product of epithelial cells lining the uterus, cervix and vagina, is secreted to facilitate uterine lubrication and microbial clearance. Predominantly composed of water and mucins, CVM also contains high levels of immuno-active proteins such as immunoglobulin A (IgA), lactoferrin and lysozyme which protect against infection by blocking adhesion and mediating microbial killing. The repertoire of cytokines, chemokines and antimicrobial peptides is predominantly generated by the secretions of endometrial epithelial cells into the uterine lumen and concentrated in the CVM. The quantity and relative proportions of these inflammatory biomarkers are affected by diverse factors including the estrus cycle and health status of the animal and therefore potentially provide important diagnostic and prognostic indicators. We propose that measuring molecular signatures in bovine CVM could be a useful approach to identifying and monitoring genital tract pathologies in beef and dairy cows.

Improved detection of biomarkers in cervico-vaginal mucus (CVM) from postpartum cattle

Background

In the postpartum cow, early diagnosis of uterine disease is currently problematic due to the lack of reliable, non-invasive diagnostic methods. Cervico-vaginal mucus (CVM) is an easy to collect potentially informative source of biomarkers for the diagnosis and prognosis of uterine disease in cows. Here, we report an improved method for processing CVM from postpartum dairy cows for the measurement of immune biomarkers. CVM samples were collected from the vagina using gloved hand during the first two weeks postpartum and processed with buffer alone or buffer containing different concentrations of the reducing agents recommended in standard protocols: Dithiothriotol (DTT) or N-Acetyl-L-Cysteine (NAC). Total protein was measured using the bicinchoninic acid (BCA) assay; interleukin 6 (IL-6), IL-8 and α1-acid glycoprotein (AGP) were measured by ELISA.

Results

We found that use of reducing agents to liquefy CVM affects protein yield and the accuracy of biomarker detection. Our improved protocol results in lower protein yields but improved detection of cytokines and chemokines. Using our modified method to measure AGP in CVM we found raised levels of AGP at seven days postpartum in CVM from cows that went on to develop endometritis.

Conclusion

We conclude that processing CVM without reducing agents improves detection of biomarkers that reflect uterine health in cattle. We propose that measurement of AGP in CVM during the first week postpartum may identify cows at risk of developing clinical endometritis.

Profiling inflammatory biomarkers in cervico-vaginal mucus (CVM) postpartum: Potential early indicators of bovine clinical endometritis?

Endometritis significantly impacts fertility and milk yield, thus reducing profitability of the dairy production. In cows that develop endometritis, normal postpartum endometrial inflammation is dysregulated. Here, we propose that endometrial inflammation is reflected in cervico-vaginal mucus (CVM) which could therefore be used as a prognostic tool. CVM was collected from 20 dairy cows (10 with clinical endometritis and 10 healthy) 7 and 21 days postpartum (DPP). Polymorphonuclear (PMN), mononuclear leukocyte and epithelial cells were counted, total protein levels were estimated and levels of IL-1β, IL-6, IL-8, serum amyloid A (SAA), haptoglobin (Hp) and C5b were analyzed by ELISA in CVM. PMN were consistently high in CVM from 7 to 21 DPP, but were higher in CVM from cows with clinical endometritis 21 DPP compared with healthy cows. In contrast, there were more epithelial cells in healthy cows 21 DPP than in clinical endometritis animals. Total protein levels decreased significantly in CVM from healthy cows between days 7 and 21 postpartum. All inflammatory biomarkers except C5b, remained high in cows with clinical endometritis from 7 to 21 DPP, indicating sustained and chronic endometrial inflammation. IL1, IL-6, IL-8 and Hp levels were higher in CVM from cows with clinical endometritis compared to healthy cows 21 DPP. Interestingly IL-1β levels were raised in CVM from clinical endometritis but not in healthy cows 7 DPP suggesting that early measurement of IL-1β levels might provide a useful predictive marker of clinical endometritis. In contrast, SAA and C5b levels were increased in healthy cows 21 DPP, compared to cows with clinical endometritis suggesting that these acute phase proteins might have an anti-inflammatory role. Our results show that CVM is convenient for profiling disease-associated changes in key inflammatory molecules postpartum and reaffirms that sustained inflammation is a key feature of clinical endometritis in the dairy cow.