Enhanced activity of carvacrol against biofilm of Staphylococcus aureus and Staphylococcus epidermidis in an acidic environment

Abstract

Carvacrol is an antimicrobial monoterpenic phenol which occurs in many plant essential oils. The aim of this study was to investigate its activity at acidic pH on staphylococcal forming and yet established biofilms, with particular focus to improve its effectiveness on Staphylococcus epidermidis biofilm. The results showed that the subinhibitory doses (1/2, 1/4 and 1/8 MIC) of carvacrol determined a higher reduction of S. epidermidis biofilm formation than that observed at neutral pH. A potentiated inhibitory effect was also observed on established biofilm, carvacrol caused either a strong reduction of biomass (>50%) and bacteria attached to polystyrene (>7 log units). The images of scanning electron microscopy and the gas‐chromatographic analysis support these results. The development of acidic formulations containing carvacrol could be an important tool to control the staphylococcal biofilm in the medical and food environment.

In Vitro Antimicrobial Activity of Carvacrol Against Shrimp Pathogens and Its Use as Feed Additive for the Pacific White Shrimp

“…To explain this outcome, the use of essential oil may be more effective than its pure and isolated compounds, such as carvacrol, considering the synergism among all the components present in essential oil, as already demonstrated in the literature (Zheng et al, 2009;Lemos et al, 2017). Furthermore, Nostro et al (2012) showed that carvacrol could be more effective when the pH of the medium is acidic, a likely consequence of the greater hydrophobicity that results in better fragmentation of the membrane lipids. Marinelli et al (2018) evidence this mechanism of action where the outer membrane and the cytoplasmic bacteria are considered the main sites of carvacrol activity resulting in functional and structural changes to the membranes, interference in the synthesis and function of nucleic acids, coagulation of the cytoplasm and leakage of its constituents, metabolic imbalance and inhibition of Quorum sensing (QS) (Knobloch et al, 1989;Sikkema et al, 1995).…”

Eugenol: A Phyto-Compound Effective against Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Clinical Strain Biofilms

“…The classical antibiotics target actively growing bacteria and are ineffective against the quiescent bacteria within biofilms [ 36 ]. Many phyto-compounds, including eugenol, have been reported to disrupt the bacterial membrane bilayer, cause membrane depolarization, and increase the membrane permeability in bacteria [ 28 , 37 , 38 , 39 ]. In the present study, we investigated the potential effects of eugenol on MRSA and MSSA clinical strains biofilms in vitro and bacterial colonization using the OM model in vivo .…”

Membrane Destruction and DNA Binding of Staphylococcus aureus Cells Induced by Carvacrol and Its Combined Effect with a Pulsed Electric Field

“…Carvacrol (5-isopropyl-2-methylphenol, CAR) is a natural antimicrobial component in the leaves of the plant Origanum vulgare . It was reported that CAR enhanced flavor and shelf life and prevented the growth of foodborne pathogens and spoilage microorganisms. − Importantly, CAR was generally safe and can be directly added to human food as a food additive . Previous studies found that the antimicrobial action of CAR may be through the disruption of the structure and function of the cytoplasmic membrane. , Recent findings have indicated that this natural antimicrobial substance might have additional intracellular targets .…”