Influence of carvacrol and thymol on the physiological attributes, enterotoxin production and surface characteristics of Staphylococcus aureus strains isolated from foods

Abstract

This study evaluated the influence of the phenolic compounds carvacrol (CAR) and thymol (THY) on some physiological characteristics and on the modulation of the secretion of some staphylococcal virulence factors, that is, coagulase and enterotoxin. This study also investigated possible mechanisms for the establishment of the anti-staphylococcal activity of these compounds. Sublethal concentrations (0.3 and 0.15 μL/mL) of CAR and THY inhibited the activity of the enzymes coagulase and lipase and led to a decrease in salt tolerance. At the tested sublethal concentrations, both CAR and THY led to a total suppression of enterotoxin production. The loss of a 260-nm-absorbing material and an efflux of potassium ions occurred immediately after the addition of CAR and THY at 0.6 and 1.2 μL/mL and increased up to 120 min of exposure. Electron microscopy of cells exposed to CAR and THY (0.6 μL/mL) revealed that individual cells appeared to be deformed, with projections of cellular material. The observations of leakage of cellular material and an altered cell surface suggest that gross damage to a cell’s cytoplasmic membrane, which results in a disruption in protein secretion, could be responsible for the anti-staphylococcal properties of CAR and THY.

Antibacterial Action of Jineol Isolated from Scolopendra subspinipes mutilans against Selected Foodborne Pathogens

“…The results clearly indicate that regulation of nucleic acid or cellular materials from the tested pathogens could be considered a significant indication of membrane structural damage. Similar to our findings, Souza et al (2013) tested the antibacterial efficacy of essential oil components, carvacrol and thymol against foodborne pathogens, and it was noted that both the compounds were able to cause membrane damaging effects, and eventually caused efflux of 260-nm nuclear components.…”

Plectranthus amboinicus essential oil and carvacrol bioactive against planktonic and biofilm of oxacillin- and vancomycin-resistant Staphylococcus aureus

“…Souza et al (2013) [ 40 ] investigated the influence of carvacrol on S. aureus strains isolated from food, and the monoterpenestrongly interfered in the permeability of the plasmic membrane, in halotolerance, in coagulase activities, and in the production of enterotoxins. In addition, the authors report that the damage caused by carvacrol in the membrane is accompanied by important changes in the surface cells of S. aureus .…”

Monoterpene isolated from the essential oil of Trachyspermum ammi is cytotoxic to multidrug-resistant Pseudomonas aeruginosa and Staphylococcus aureus strains

“…Thymol has a strong antimicrobial effect either when used alone or in combination with other biocides such as carvacrol (6) (20) . According to previous studies of Gram-positive test strains, these compounds strongly interfere with physiological characteristics such as cytoplasmic membrane permeability, coagulase activity, salt tolerance, and enterotoxin production (6) (21) . The oil may also influence the signal transduction in the agr system, a global regulator of virulence factor expression in staphylococci (21) .…”

“…According to previous studies of Gram-positive test strains, these compounds strongly interfere with physiological characteristics such as cytoplasmic membrane permeability, coagulase activity, salt tolerance, and enterotoxin production (6) (21) . The oil may also influence the signal transduction in the agr system, a global regulator of virulence factor expression in staphylococci (21) . A previous study indicated that these types of mechanism of action were responsible for growth inhibition in P. aeruginosa reference strains (22) (23) .…”