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

Cirino, Isis Caroline S; Menezes-Silva, Suellen Maria P; Silva, Helena Tainá D; Souza, Evandro Leite de; Siqueira-Júnior, José P.

doi:10.1159/000381175

Cited by 40 publications

(28 citation statements)

References 15 publications

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“…Resistance to carvacrol is likely attributable to the MexAB-OprM efflux pump. The relationship between carvacrol and RND systems has been previously demonstrated in other bacterial species (Cirino et al, 2014). Further, Thymus maroccanus essential oil and its major components (carvacrol and thymol) were able to select variants of E. coli that overexpress the AcrAB efflux pump (Fadli et al, 2014).…”

Section: Discussionmentioning

confidence: 56%

MexAB-OprM Efflux Pump of Pseudomonas aeruginosa Offers Resistance to Carvacrol: A Herbal Antimicrobial Agent

et al. 2019

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Carvacrol is a herbal antimicrobial agent with in vitro activity against several bacterial pathogens. However, multidrug resistant strains of Pseudomonas aeruginosa are resistant to herbal antimicrobial compounds including carvacrol. Resistance of P. aeruginosa to carvacrol is not well studied. This study was aimed to identify the gene(s) associated with carvacrol resistance, thus to understand its mechanisms in P. aeruginosa. A herbal drug resistant strain was isolated from a hospital environment. Carvacrol sensitive mutant was generated using transposon mutagenesis. The inactivated gene in the mutant was identified as mexA, which is part of the mexAB-oprM operon. Inactivation of the mexA gene resulted in a >31-fold reduction in MIC of carvacrol, whereas a >80-fold reduction was observed in the presence of drug efflux inhibitor phenylalanine-arginine β-naphthylamide (PAβN). The parental herbal-resistant strain was completely killed within 3 h of incubation in the presence of carvacrol and PAβN. The mexA inactivation did not affect the resistance to other herbal compounds used. The results demonstrate that resistance to carvacrol in P. aeruginosa is mediated by the MexAB-OprM efflux pump.

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Section: Discussionmentioning

confidence: 56%

MexAB-OprM Efflux Pump of Pseudomonas aeruginosa Offers Resistance to Carvacrol: A Herbal Antimicrobial Agent

et al. 2019

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“…The targets included DNA synthesis (106) and the cytoplasmic membrane (107). EOs from Origanum vulgare L., carvacrol and thymol, were identified as putative efflux pump inhibitors facilitating the uptake of antibiotics, norfloxacin, erythromycin, and tetracycline (108).…”

Section: Essential Oils: Broad-spectrum Compositions Multiple Mechanmentioning

confidence: 99%

Control of Biofilm Formation: Antibiotics and Beyond

Algburi

Comito

Kashtanov

et al. 2017

Appl Environ Microbiol

198

161

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Biofilm-associated bacteria are less sensitive to antibiotics than freeliving (planktonic) cells. Furthermore, with variations in the concentration of antibiotics throughout a biofilm, microbial cells are often exposed to levels below inhibitory concentrations and may develop resistance. This, as well as the irresponsible use of antibiotics, leads to the selection of pathogens that are difficult to eradicate. The Centers for Disease Control and Prevention use the terms "antibiotic" and "antimicrobial agent" interchangeably. However, a clear distinction between these two terms is required for the purpose of this assessment. Therefore, we define "antibiotics" as pharmaceutically formulated and medically administered substances and "antimicrobials" as a broad category of substances which are not regulated as drugs. This comprehensive minireview evaluates the effect of natural antimicrobials on pathogens in biofilms when used instead of, or in combination with, commonly prescribed antibiotics.

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“…Moreover, their aromatic rings, naturally able to delocalize electrons, can contribute to the reduction of membrane proton gradient, thus resulting in a collapse of the proton motive force and the depletion of ATP [47,48], with a potential consequence even on virulence gene expression levels because of an extensive effect on several bacterial enzymes [15], finally resulting in an impairment of virulence functions such as the gene expression of bacterial toxins like LT, STa, and STb. This would also suggest a mechanism of action of these compounds similar to certain antibiotics like colistin, doxycycline, and bacitracin, for example, that would implicate a possible synergy between these categories of molecules as a new frontier of therapeutic approach against enterotoxin-producing pathogens [9,[49][50][51][52][53][54].…”

Section: Discussionmentioning

confidence: 99%

Nature-Identical Compounds and Organic Acids Reduce E. coli K88 Growth and Virulence Gene Expression In Vitro

Bonetti

Tugnoli²,

Rossi³

et al. 2020

Toxins

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Post-weaning diarrhoea (PWD) is one of the long-standing challenges in pig husbandry. Due to the risks of resistance caused by antibiotics (AB) misuse, conventional treatments against Escherichia coli K88 (E. coli K88), the PWD etiological agent, urgently need to be replaced. Organic acids (OA) and nature-identical compounds (NIC) are currently finding a central role in infection management thanks to their recognized antimicrobial activity. This study investigated the susceptibility of an E. coli K88 field strain to a wide panel of AB, NIC, and OA. Secondly, we evaluated the ability of sub-lethal doses of the most active compounds to modulate the expression of E. coli K88 virulence genes. Results showed that the bacterial strain was resistant to many of the tested antibiotics, but an antimicrobial action was registered for selected NIC and OA. The quantitative PCR analysis revealed that thymol, carvacrol, eugenol, and benzoic acid were able to downregulate (p < 0.05) the expression of bacterial genes related to motility, adhesion to enterocytes, heat-labile (LT) and heat-stable (ST) toxin secretion, quorum sensing, and biofilm formation. Therefore, this study demonstrated that selected OA and NIC not only control E. coli K88 growth but also modulate the expression of many virulence genes at sub-lethal doses, thus offering new insights on their mechanism of action and suggesting a powerful tool to manage PWD.

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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>

Cited by 40 publications

References 15 publications

MexAB-OprM Efflux Pump of Pseudomonas aeruginosa Offers Resistance to Carvacrol: A Herbal Antimicrobial Agent

MexAB-OprM Efflux Pump of Pseudomonas aeruginosa Offers Resistance to Carvacrol: A Herbal Antimicrobial Agent

Control of Biofilm Formation: Antibiotics and Beyond

Nature-Identical Compounds and Organic Acids Reduce E. coli K88 Growth and Virulence Gene Expression In Vitro

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