Effects of Sublethal Thymol, Carvacrol, and
            <i>trans</i>
            -Cinnamaldehyde Adaptation on Virulence Properties of
            <i>Escherichia coli</i>
            O157:H7

Yuan, Wenqian; Yuk, Hyun‐Gyun

doi:10.1128/aem.00271-19

Cited by 48 publications

(32 citation statements)

References 51 publications

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“…Our study revealed that selected antibiotics, NIC, and benzoic acid downregulate the expression of motA and faeG genes crucial for bacterial motility and cellular adhesion. The same trend was registered on E. coli O157:H7: an important downregulation of genes related to flagella was shown for bacteria conditioned with sub-MIC doses of thymol and carvacrol [41].…”

Section: Discussionsupporting

confidence: 73%

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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Section: Discussionsupporting

confidence: 73%

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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“…Thymol has been reported to exhibit several biological activities that could reduce pathogenicity of a number of bacterial pathogens. Yuan and Yuk [37] demonstrated that thymol could reduce motility, biofilm formation, and efflux pump activity of Escherichia. coli O157:H7 with an induction of antimicrobial resistance.…”

Section: Discussionmentioning

confidence: 99%

Thymol Protects Channel Catfish from Aeromonas hydrophila Infection by Inhibiting Aerolysin Expression and Biofilm Formation

et al. 2020

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Aeromonas hydrophila is an opportunistic pathogen responsible for a number of diseases in freshwater farming. Moreover, the bacterium has been identified as a zoonotic pathogen that threatens human health. Antibiotics are widely used for treatments of infectious diseases in aquaculture. However, the abuse of antibiotics has led to the emergence of antimicrobial resistant strains. Thus, novel strategies are required against resistant A. hydrophila strains. The quorum sensing (QS) system, involved in virulence factor production and biofilm formation, is a promising target in identifying novel drugs against A. hydrophila infections. In this study, we found that thymol, at sub-inhibitory concentrations, could significantly reduce the production of aerolysin and biofilm formation by inhibiting the transcription of genes aerA, ahyI, and ahyR. These results indicate that thymol inhibits the quorum sensing system. The protective effects of thymol against A. hydrophila mediated cell injury were determined by live/dead assay and lactate dehydrogenase (LDH) release assay. Moreover, the in vivo study showed that thymol could significantly decrease the mortality of channel catfish infected with A. hydrophila. Taken together, these findings demonstrate that thymol could be chosen as a phytotherapeutic candidate for inhibiting quorum sensing system-mediated aerolysin production and biofilm formation in A. hydrophila.

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“…Bacteria have, among their survival strategies, the flexibility of altering the mRNA expression patterns in response to environmental stress [ 37 ], as for example when cultured with non-lethal concentrations of antimicrobials. Since the mechanism of action of NIC involves the alteration of the bacterial cell membrane and induces an intracellular ATP leakage [ 29 , 38 ], it can be postulated that bacteria subjected to stressful sub-lethal concentrations of NIC switch their energies from motility or virulence systems to vital and essential processes, until a more favorable environment is restored [ 39 ]. Recently, it has been demonstrated that a stress induced by thymol influences the S. typhimurium proteome, downregulating genes involved in chemotaxis, motility, and virulence [ 20 ].…”

Section: Discussionmentioning

confidence: 99%

Thymol and Carvacrol Downregulate the Expression of Salmonella typhimurium Virulence Genes during an In Vitro Infection on Caco-2 Cells

Giovagnoni

Rossi²,

Tugnoli³

et al. 2020

Microorganisms

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Salmonella typhimurium is one of the major bacteria responsible for gastroenteritis in humans caused by foodborne pathogens. As pork is one of the main routes of transmission, bioactive compounds used as feed additives may be an important strategy to control Salmonella typhimurium. The aim of this study was to assess the antimicrobial activity of several organic acids and nature identical compounds against Salmonella typhimurium ATCC®® 6994™. Moreover, the effect of sub-lethal concentrations of thymol and carvacrol in counteracting a Salmonella typhimurium in vitro infection on Caco-2 cells was evaluated, focusing on the maintenance of the epithelial barrier and the alteration of Salmonella virulence genes. The results showed a protective effect of the compounds on the integrity of the intestinal monolayer, improving transepithelial electrical resistance and bacterial translocation compared to the non-treated cells. A real-time PCR study highlighted a significant downregulation of the main virulence genes of Salmonella (hilA, prgH, invA, sipA, sipC, sipD, sopB, sopE2). These findings indicate that thymol and carvacrol could be good candidates for the control of Salmonella typhimurium in pigs.

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Effects of Sublethal Thymol, Carvacrol, and trans -Cinnamaldehyde Adaptation on Virulence Properties of Escherichia coli O157:H7

Cited by 48 publications

References 51 publications

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

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

Thymol Protects Channel Catfish from Aeromonas hydrophila Infection by Inhibiting Aerolysin Expression and Biofilm Formation

Thymol and Carvacrol Downregulate the Expression of Salmonella typhimurium Virulence Genes during an In Vitro Infection on Caco-2 Cells

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