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Essential oils inhibit the bovine respiratory pathogens Mannheimia haemolytica , Pasteurella multocida and Histophilus somni and have limited effects on commensal bacteria and turbinate cells in vitro
Author(s) -
Amat S.,
Baines D.,
Timsit E.,
Hallewell J.,
Alexander T.W.
Publication year - 2019
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.14238
Subject(s) - bovine respiratory disease , pasteurella multocida , microbiology and biotechnology , antimicrobial , bacteria , biology , pasteurellaceae , cytotoxicity , in vitro , antibiotics , haemophilus influenzae , biochemistry , genetics
Abstract Aims The objective of this study was to determine antimicrobial activities of essential oils ( EO s) 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 EO s was determined using gas chromatography–mass spectrometry. All EO s were first evaluated for growth inhibition of a single BRD pathogen Mannheimia haemolytica serotype 1 strain (L024A). The most inhibitory EO s ( 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 EO s was also evaluated using a BT cell line. The EO s 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 EO s, the MIC was 2–32 fold greater against commensal bacteria, compared to BRD ‐associated pathogens. No cytotoxic effects of EO s against BT cells were observed within the tested range of concentrations (0·0125–0·4%, v/v). Conclusions The EO s 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 EO s may have potential for intra‐nasal administration to mitigate bovine respiratory pathogens in feedlot cattle.