ARTICLE | doi:10.20944/preprints202207.0105.v1
Subject: Medicine & Pharmacology, Veterinary Medicine Keywords: Melaleuca armillaris; essential oil; erythromycin; Staphylococcus aureus; synergism; mastitis
Online: 7 July 2022 (04:05:55 CEST)
Staphylococcus aureus frequently causes subclinical mastitis around the world with high impact in milk industry and public health. Essential oils (EO) are recognized antimicrobials that can be synergistic with antibiotics. The main objective of this study was evaluating the essential oil (EO) of Melaleuca armillaris as an adjuvant of erythromycin (ERY) for the alternative treatment of bovine mastitis caused by S. aureus. The Minimum Inhibitory and Bactericidal Concentrations (MIC and MBC) of EO, ERY, and its combinations were established against S. aureus at different pHs (7.4, 6.5 and 5.0), emulating extra and intracellular conditions. Sensible (N=3) and resistant (N=3) strains to ERY and S. aureus ATCC 29213 as control were used. Math models were applied to described the antibacterial activity of EO and combinations EO-ERY. The EO was bactericidal against all the strains independently of the pH with a slightly improvement in acid conditions. The synergism between EO and ERY was estimated by the Fractional Inhibitory Concentration Index (FIC) and by mathematical modeling of the bacterial killing data. Synergism was observed with ERY, where combinations had bactericidal activity also even with pH modification. M. armillaris EO is an interesting adjuvant for ERY, being a promissory option for further analysis of intracellular efficacy against S. aureus.
ARTICLE | doi:10.20944/preprints202102.0061.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Staphylococcus aureus; Melaleuca armillaris; essential oil; Gompertz model; Sigmoid model; antibacterial
Online: 1 February 2021 (16:02:30 CET)
Essential oils (EO) are a great antimicrobial resource against bacterial resistance in public health. Math models are useful describing the growth, survival, and inactivation of microorganisms against antimicrobials. We evaluated the antimicrobial activity of M. armillaris EO obtained from plants placed in the province of Buenos Aires (Argentina) against Staphylococcus aureus. Minimum Inhibitory and Bactericidal Concentrations were close and decreased slightly acidifying the medium from pH 7.4 to 6.5 and 5.0. This result was also evidenced by applying a sigmoid model, where the time and EO concentration necessaries to achieve 50% of the maximum effect decreased when medium was acidified. Moreover, at pH 7.4, applying the Gompertz model, we found that subinhibitory concentrations of EO decreased the growth rate and the maximum population density, and increased the latency period respect to the control. Additionally, we established physicochemical parameters for quality control and standardization of M. armillaris EO. Mathematical modelling allowed us to estimate key parameters in the behavior of S. aureus and Melaleuca armillaris EO at different pHs. This is interesting in situations where the pH changes are relevant, such as the control of intracellular infections in public health or the development of preservatives for food industry.