Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA.
Int J Food Microbiol. 2012 Jun 15;157(1):88-94. doi: 10.1016/j.ijfoodmicro.2012.04.018. Epub 2012 May 1.
Listeria monocytogenes (LM) is a major foodborne pathogen causing septicemia, meningitis and death in humans. LM infection is preceded by its attachment to and invasion of human intestinal epithelium followed by systemic spread. The major virulence factors in LM include motility, hemolysin and lecithinase production. Reducing LM attachment to and invasion of host tissue and production of virulence factors could potentially control listeriosis in humans. This study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) of three, generally regarded as safe (GRAS)-status, plant-derived antimicrobial compounds in reducing LM attachment to and invasion of human colon adenocarcinoma (Caco-2) and human brain microvascular endothelial cells (HBMEC). Additionally, the effect of these compounds on the aforementioned LM virulence factors was studied. The compounds and their respective SICs used relative to their MICs were trans-cinnamaldehyde (TC 0.50mM, 0.75mM with the MIC of 0.90mM), carvacrol (CR 0.50mM, 0.65mM with the MIC of 0.75mM), and thymol (TY 0.33mM, 0.50mM with the MIC of 0.60mM). All three-plant antimicrobials reduced LM adhesion to and invasion of Caco-2 and HBMEC (p<0.05). The compounds also decreased LM motility, hemolysin production and lecithinase activity (p<0.05). Real-time PCR data revealed that TC, CR, and TY down-regulated the expression of LM virulence genes by >3.0 folds compared to controls (p<0.05). Results suggest that TC, CR, and TY could potentially be used to control LM infection; however, in vivo studies are necessary to validate these results.
李斯特菌（LM）是一种主要的食源性病原体，可导致人类败血症、脑膜炎和死亡。LM 感染之前，它会附着并侵入人体肠道上皮细胞，然后进行全身传播。LM 的主要毒力因子包括运动性、溶血素和卵磷脂酶的产生。减少 LM 对宿主组织的附着和入侵以及毒力因子的产生，可能有助于控制人类李斯特菌病。本研究调查了三种被认为安全（GRAS）的植物源抗菌化合物在亚抑制浓度（SIC，不抑制细菌生长的浓度）下，降低李斯特菌附着和侵袭人结肠腺癌细胞（Caco-2）和人脑微血管内皮细胞（HBMEC）的功效。此外，还研究了这些化合物对上述 LM 毒力因子的影响。相对于 MIC，使用的化合物及其相应的 SIC 为肉桂醛（TC 0.50mM，0.75mM，MIC 为 0.90mM）、香芹酚（CR 0.50mM，0.65mM，MIC 为 0.75mM）和百里香酚（TY 0.33mM，0.50mM，MIC 为 0.60mM）。三种植物抗菌剂均降低了 LM 对 Caco-2 和 HBMEC 的粘附和侵袭（p<0.05）。这些化合物还降低了 LM 的运动性、溶血素产生和卵磷脂酶活性（p<0.05）。实时 PCR 数据显示，与对照组相比，TC、CR 和 TY 使 LM 毒力基因的表达下调了>3.0 倍（p<0.05）。结果表明，TC、CR 和 TY 可能可用于控制 LM 感染；然而，需要进行体内研究来验证这些结果。
