Antimicrobial resistance (AMR) represents a serious threat to human health, as well as to food-producing animals and the environment. AMR is a growing phenomenon, while antibiotic efficacy against human and zoonotic infections is decreasing [1]. Salmonellosis is the 2nd most common zoonosis in Europe, and recent studies highlight multidrug resistance (MDR) of numerous Salmonella strains to the most commonly used antimicrobial agents [2]. EOs could meet some of the strategic objectives outlined in the WHO's Global Action Plan on AMR. Salmonella is the most frequently isolated bacterial agent in food-borne infections. Food-producing animals are the main reservoirs of infection, with animal-derived foods (meat, eggs and milk) sources of transmission. The aim of the study was to evaluate antibacterial efficacy of single EOs (Lavandula intermedia and Origanum vulgare) and of GR-OLI (25% commercial solution of an unknown mixture of Eucalyptus globulus, Satureja montana, Citrus aurantium var. dulcis, Thymus vulgaris, Melaleuca alternifolia, Citrus limon, Lavanda hybrida, Melaleuca cajeputi, Thymus capitatus) against Salmonella (29 strains) isolated from swine and poultry farms and against beneficial microorganisms used as probiotics, including Saccharomyces cerevisiae, S. boulardii, Enterococcus faecium and Bifidobacterium thermoacidophilum (6 strains). EO efficacy was evaluated through MIC analysis according to EUCAST guidelines [3]. The action of scalar concentrations between 2% v / v and 0.06% v / v for OEs and between 8% v / v and 0.25% v / v for GR-OLI was evaluated. Moreover, the EOs with sub-MIC values capable of reducing bacterial growth were tested in CaCo-2 cell adhesion and biofilm experiments using Salmonella (12 strains). GR-OLI and O. vulgare proved more effective than L. intermedia against multidrug-resistant Salmonella strains. The EOs evaluated had higher MIC values against probiotics than against Salmonella. GR-OLI also decreased biofilm formation and reduced adhesion of Salmonella strains to CaCo-2 cells. GR-OLI showed higher efficacy against multidrug-resistant Salmonella strains than against drug-sensitive Salmonella strains. Our data on the evaluated EOs require further investigation and confirmation, also exploring the possibility of resistance development. However, sub-MIC doses of GR-OLI could prove to be an interesting strategy for reducing Salmonella presence in intensive swine and poultry farms [1] Singer A.C. et al. Review of antimicrobial resistance in the environment and its relevance to environmental regulators, Front Microbiol., 7:1-22, 2016. [2] Santos F.S., Novales M.G.M. Essential oils from aromatic herbs as antimicrobial agents, Curr. Opin. Biotechnol., 23:136–141, 2012. [3] EUCAST, 2017. European Committee for Antimicrobial Susceptibility Testing. Version 7.1. www.eucast.org.
ANTIMICROBIAL ACTIVITY OF SINGLE AND BLENDED ESSENTIAL OILS AGAINST PROBIOTICS AND SALMONELLA ISOLATES COLLECTED FROM FARMED POULTRY AND SWINE
Maura Di Vito;Anna Zaghini;Monica Modesto;Paola Mattarelli
2019
Abstract
Antimicrobial resistance (AMR) represents a serious threat to human health, as well as to food-producing animals and the environment. AMR is a growing phenomenon, while antibiotic efficacy against human and zoonotic infections is decreasing [1]. Salmonellosis is the 2nd most common zoonosis in Europe, and recent studies highlight multidrug resistance (MDR) of numerous Salmonella strains to the most commonly used antimicrobial agents [2]. EOs could meet some of the strategic objectives outlined in the WHO's Global Action Plan on AMR. Salmonella is the most frequently isolated bacterial agent in food-borne infections. Food-producing animals are the main reservoirs of infection, with animal-derived foods (meat, eggs and milk) sources of transmission. The aim of the study was to evaluate antibacterial efficacy of single EOs (Lavandula intermedia and Origanum vulgare) and of GR-OLI (25% commercial solution of an unknown mixture of Eucalyptus globulus, Satureja montana, Citrus aurantium var. dulcis, Thymus vulgaris, Melaleuca alternifolia, Citrus limon, Lavanda hybrida, Melaleuca cajeputi, Thymus capitatus) against Salmonella (29 strains) isolated from swine and poultry farms and against beneficial microorganisms used as probiotics, including Saccharomyces cerevisiae, S. boulardii, Enterococcus faecium and Bifidobacterium thermoacidophilum (6 strains). EO efficacy was evaluated through MIC analysis according to EUCAST guidelines [3]. The action of scalar concentrations between 2% v / v and 0.06% v / v for OEs and between 8% v / v and 0.25% v / v for GR-OLI was evaluated. Moreover, the EOs with sub-MIC values capable of reducing bacterial growth were tested in CaCo-2 cell adhesion and biofilm experiments using Salmonella (12 strains). GR-OLI and O. vulgare proved more effective than L. intermedia against multidrug-resistant Salmonella strains. The EOs evaluated had higher MIC values against probiotics than against Salmonella. GR-OLI also decreased biofilm formation and reduced adhesion of Salmonella strains to CaCo-2 cells. GR-OLI showed higher efficacy against multidrug-resistant Salmonella strains than against drug-sensitive Salmonella strains. Our data on the evaluated EOs require further investigation and confirmation, also exploring the possibility of resistance development. However, sub-MIC doses of GR-OLI could prove to be an interesting strategy for reducing Salmonella presence in intensive swine and poultry farms [1] Singer A.C. et al. Review of antimicrobial resistance in the environment and its relevance to environmental regulators, Front Microbiol., 7:1-22, 2016. [2] Santos F.S., Novales M.G.M. Essential oils from aromatic herbs as antimicrobial agents, Curr. Opin. Biotechnol., 23:136–141, 2012. [3] EUCAST, 2017. European Committee for Antimicrobial Susceptibility Testing. Version 7.1. www.eucast.org.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
