S Amat1,2, D Baines1, E Timsit2,3, J Hallewell1, T W Alexander1. 1. Agriculture and Agri-Food Canada, Lethbridge, AB, Canada. 2. Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada. 3. Simpson Ranch Chair in Beef Cattle Health and Wellness, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
Abstract
AIMS: The objective of this study was to determine antimicrobial activities of essential oils (EOs) against bovine respiratory disease (BRD) pathogens and nasopharyngeal commensal bacteria, as well as cytotoxicity in bovine turbinate (BT) cells in vitro. METHODS AND RESULTS: The chemical composition of 16 EOs was determined using gas chromatography-mass spectrometry. All EOs were first evaluated for growth inhibition of a single BRD pathogen Mannheimia haemolytica serotype 1 strain (L024A). The most inhibitory EOs (n = 6) were then tested for antimicrobial activity against multidrug-resistant strains of M. haemolytica (serotypes 1, 2 and 6); the BRD pathogens Pasteurella multocida and Histophilus somni, as well as commensal bacteria that were isolated from the nasopharynx of feedlot cattle. The cytotoxicity of 10 EOs was also evaluated using a BT cell line. The EOs ajowan, thyme and fennel most effectively inhibited all BRD pathogens tested including multidrug-resistant strains with minimum inhibitory concentrations (MIC) of ≤0·025% (volume/volume, v/v). For these EOs, the MIC was 2-32 fold greater against commensal bacteria, compared to BRD-associated pathogens. No cytotoxic effects of EOs against BT cells were observed within the tested range of concentrations (0·0125-0·4%, v/v). CONCLUSIONS: The EOs ajowan, thyme and fennel inhibited M. haemolytica, P. multocida and H. somni at a concentration of 0·025% and had minimal antimicrobial activity against nasopharyngeal commensal bacteria and cytotoxicity against BT cells. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated that EOs may have potential for intra-nasal administration to mitigate bovine respiratory pathogens in feedlot cattle.
AIMS: The objective of this study was to determine antimicrobial activities of essential oils (EOs) against bovinerespiratory disease (BRD) pathogens and nasopharyngeal commensal bacteria, as well as cytotoxicity in bovine turbinate (BT) cells in vitro. METHODS AND RESULTS: The chemical composition of 16 EOs was determined using gas chromatography-mass spectrometry. All EOs were first evaluated for growth inhibition of a single BRD pathogen Mannheimia haemolytica serotype 1 strain (L024A). The most inhibitory EOs (n = 6) were then tested for antimicrobial activity against multidrug-resistant strains of M. haemolytica (serotypes 1, 2 and 6); the BRD pathogens Pasteurella multocida and Histophilus somni, as well as commensal bacteria that were isolated from the nasopharynx of feedlot cattle. The cytotoxicity of 10 EOs was also evaluated using a BT cell line. The EOs ajowan, thyme and fennel most effectively inhibited all BRD pathogens tested including multidrug-resistant strains with minimum inhibitory concentrations (MIC) of ≤0·025% (volume/volume, v/v). For these EOs, the MIC was 2-32 fold greater against commensal bacteria, compared to BRD-associated pathogens. No cytotoxic effects of EOs against BT cells were observed within the tested range of concentrations (0·0125-0·4%, v/v). CONCLUSIONS: The EOs ajowan, thyme and fennel inhibited M. haemolytica, P. multocida and H. somni at a concentration of 0·025% and had minimal antimicrobial activity against nasopharyngeal commensal bacteria and cytotoxicity against BT cells. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated that EOs may have potential for intra-nasal administration to mitigate bovine respiratory pathogens in feedlot cattle.
Authors: Samat Amat; Edouard Timsit; Danica Baines; Jay Yanke; Trevor W Alexander Journal: Appl Environ Microbiol Date: 2019-10-16 Impact factor: 4.792
Authors: Nguyen Thi Bich Van; On Thuong Vi; Nguyen Thi Phuong Yen; Nguyen Thi Nhung; Nguyen Van Cuong; Bach Tuan Kiet; Nguyen Van Hoang; Vo Be Hien; Guy Thwaites; James Campell; Marc Choisy; Juan Carrique-Mas Journal: J Appl Microbiol Date: 2021-09-28 Impact factor: 4.059