Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Department of Animal, Poultry and Aquatics, Institute of Agriculture, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran.
Vet Med Sci. 2024 Nov;10(6):e70088. doi: 10.1002/vms3.70088.
The investigation on natural antimicrobial compounds against zoonotic pathogens has gained more attention due to the public health concerns regarding the emergence of antimicrobial resistance.
The current study aimed to assess the effects of thyme essential oil at sub-minimal inhibitory concentrations (sub-MICs) on bacterial growth and expression of some virulence genes in Salmonella enteritidis.
The bacterial growth rate and the expression of four virulence genes in S. enteritidis during 18-72 h of exposure to the essential oil at 25%-75% MIC were evaluated via colony counting and real-time polymerase chain reaction (PCR), respectively.
Sub-inhibitory concentrations of thyme essential oil significantly reduced the growth rate compared to the control. Expression of all tested virulence genes was also reduced by the essential oil in a significant dose- and time-dependent manner. As an example, decreased down-regulation of hilA, spv, sefA and invA as 1.7-, 4.14-, 2.92- and 1.04-fold in 25% MIC and 6.42-, 7.81-, 4.4- and 3.75-fold in 75% MIC was observed, respectively, after 24 h of incubation. Likewise, levels of transcription for hilA, spv, sefA and invA were reduced 4.75-, 6.95-, 3.75- and 2.98-fold after 18 h and 9.54-, 8.81-, 5.65- and 4.77-fold, respectively, after 72 h in 75% MIC compared to the control.
According to our data, aside from the growth inhibitory effect of thyme essential oil, the results of current study highlight the potential of thyme for reducing the transcriptional level of virulence genes and therefore the pathogenicity of S. enteritidis.
由于公众对出现抗微生物药物耐药性的担忧，针对动物源致病菌的天然抗微生物化合物的研究受到了更多关注。
本研究旨在评估百里香精油在亚最小抑菌浓度（sub-MIC）下对肠炎沙门氏菌细菌生长和某些毒力基因表达的影响。
通过平板计数和实时聚合酶链反应（PCR）分别评估精油在 25%-75%MIC 下暴露于细菌 18-72 小时期间对细菌生长速度和肠炎沙门氏菌 4 个毒力基因表达的影响。
亚抑制浓度的百里香精油与对照组相比，显著降低了生长速度。精油还以剂量和时间依赖的方式显著降低了所有测试毒力基因的表达。例如，在 25%MIC 下，hilA、spv、sefA 和 invA 的下调分别减少了 1.7、4.14、2.92 和 1.04 倍，在 75%MIC 下，下调分别减少了 6.42、7.81、4.4 和 3.75 倍，分别在孵育 24 小时后观察到。同样，在 75%MIC 下，hilA、spv、sefA 和 invA 的转录水平分别在 18 小时后减少了 4.75、6.95、3.75 和 2.98 倍，在 72 小时后减少了 9.54、8.81、5.65 和 4.77 倍，与对照组相比。
根据我们的数据，除了百里香精油的生长抑制作用外，本研究结果还强调了百里香降低肠炎沙门氏菌毒力基因转录水平从而降低其致病性的潜力。
