Tolerance response of multidrug-resistant Salmonella enterica strains to habituation to Origanum vulgare L. essential oil

Abstract

Multidrug-resistant Salmonella enterica isolates from human outbreaks or from poultry origin were investigated for their ability to develop direct-tolerance or cross-tolerance to sodium chloride, potassium chloride, lactic acid, acetic acid, and ciprofloxacin after habituation in subinhibitory amounts ( of the minimum inhibitory concentration – (MIC) and of the minimum inhibitory concentration – MIC) of Origanum vulgare L. essential oil (OVEO) at different time intervals. The habituation of S. enterica to OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by the modulation of MIC values. However, cells habituated to OVEO maintained or increased susceptibility to the tested antimicrobials agents, with up to fourfold double dilution decrease from previously determined MIC values. This study reports for the first time the non-inductive effect of OVEO on the acquisition of direct-tolerance or cross-tolerance in multidrug-resistant S. enterica strains to antimicrobial agents that are largely used in food preservation, as well as to CIP, the therapeutic drug of salmonellosis.

The Essential Oil from <b><i>Origanum vulgare</i></b> L. and Its Individual Constituents Carvacrol and Thymol Enhance the Effect of Tetracycline against <b><i>Staphylococcus aureus</i></b>

“…The presence of different lipophilic hydrocarbon compounds, such as myrcene, pinene, cymene, camphene, limonene and terpinene [4], could provide the increased lipophilicity in OVEO and in addition could be able to act in a synergistic fashion. Lipophilic hydrocarbon constituents often found in essential oils are capable of causing loss of membrane integrity and affecting the proteins embedded in the bacterial membrane - such as those forming protein-efflux pumps - probably as a consequence of more severe changes in the lipid environment in membranes disturbing the normal physiological functions of these organelles [15]. …”

Inhibition of Staphylococcus aureus cocktail using the synergies of oregano and rosemary essential oils or carvacrol and 1,8-cineole

“…The CAR and CIN were purchased from Sigma Aldrich (Sigma, France). Emulsions of the essential oils or constituents were prepared in brain heart infusion broth (BHI, Himedia, India) with a range of concentrations (80–0.312 μL/mL) using Tween 80 (1%, v/v; Sigma–Aldrich, USA) as an emulsifier ( Monte et al, 2015 ). Tween 80 at the higher assayed concentration (1%, v/v) presented no inhibitory effects against the assayed S. aureus cocktail.…”

Antimicrobial Potential of Carvacrol against Uropathogenic Escherichia coli via Membrane Disruption, Depolarization, and Reactive Oxygen Species Generation

“…In recent years, there have been many reports on the use of essential oil or its components, as potent antimicrobials against a variety of pathogenic bacteria ( Di Pasqua et al, 2007 ; Bajpai et al, 2009 ). Carvacrol, which is present in essential oils of Origanum vulgare, Thymus vulgaris, Trachyspermum ammi, Lepidium africanum , and Citrus bergamia , has been widely studied as an antimicrobial, antiviral, and anticancer agent ( Johny et al, 2010 ; Dandlen et al, 2011 ; Nostro and Papalia, 2012 ; Monte et al, 2014 ; Honório et al, 2015 ). Carvacrol is a hydrophobic monoterpene in nature that easily penetrates the cell membranes of bacteria, leading to disruption of cell membrane integrity as well as release of bacterial cell contents ( Cristani et al, 2007 ; Di Pasqua et al, 2007 ; Magi et al, 2015 ).…”