Longhi Catia, Ammendolia Maria Grazia, Conte Maria Pia, Seganti Lucilla, Iosi Francesca, Superti Fabiana
Department of Public Health and Infectious Diseases, Sapienza University, P.le A. Moro 5, 00185 Rome, Italy.
Department of Technology and Health, National Health Institute, Via Regina Elena 299, 00185 Rome, Italy.
Food Microbiol. 2014 Sep;42:66-71. doi: 10.1016/j.fm.2014.02.015. Epub 2014 Feb 28.
It has been suggested that the rarity of human listeriosis due to Listeria ivanovii reflects not only host tropism factors but also the rare occurrence of this species in the environment, compared with Listeria monocytogenes. In the present study we evaluate the effects on the reference strain L. ivanovii ATCC 19119 behaviour of two combined stresses, low iron availability and acid environment, that bacteria can encounter in the passage from saprophytic life to the host. In these conditions, L. ivanovii evidenced a different behaviour compared to L. monocytogenes exposed to similar conditions. L. ivanovii was not able to mount an acid tolerance response (ATR) even if, upon entry into the stationary phase in iron-loaded medium, growth phase-dependent acid resistance (AR) was evidenced. Moreover, bacteria grown in iron excess and acidic pH showed the higher invasion value in Caco-2 cells, even though it was not able to efficiently multiply. On the contrary, low iron and acidic conditions improved invasion ability in amniotic WISH cells.
有人认为，与单核细胞增生李斯特菌相比，由伊氏李斯特菌引起的人类李斯特菌病罕见不仅反映了宿主嗜性因素，还反映了该菌种在环境中出现的频率较低。在本研究中，我们评估了低铁可用性和酸性环境这两种复合应激对参考菌株伊氏李斯特菌ATCC 19119行为的影响，细菌在从腐生生活过渡到宿主的过程中可能会遇到这些应激。在这些条件下，与暴露于类似条件下的单核细胞增生李斯特菌相比，伊氏李斯特菌表现出不同的行为。即使在铁负载培养基进入稳定期时，伊氏李斯特菌也无法产生耐酸反应（ATR），但显示出与生长阶段相关的耐酸性（AR）。此外，在铁过量和酸性pH条件下生长的细菌在Caco-2细胞中表现出较高的侵袭值，尽管它不能有效地增殖。相反，低铁和酸性条件提高了在羊膜WISH细胞中的侵袭能力。
