The effect of wine on the survival and invasiveness ability of listeria monocytogenes

Abstract

Listeria monocytogenes is a foodborne pathogen known for the severity of its infection, listeriosis, and for its capability of growing at harsh conditions such as refrigeration temperatures, wide pH range, low water activity and high salinity. L. monocytogenes can induce its own phagocytosis by the host’s intestinal epithelial cells, followed by replication and direct transfer to other cells. Wine is a complex solution with proved antimicrobial activity due to its content of ethanol, organic acids and phenolics. This work focused on (i) comparing the susceptibility of food and clinical strains of L. monocytogenes towards wine, and (ii) on the evaluation of the influence of wine on the invasiveness ability of L. monocytogenes using the human intestinal epithelial cells Caco-2 cell line. Thirty-nine isolates of L. monocytogenes were used in this study, 22 of food and 17 of clinical origin belonging to different serogroups. To measure the inactivation effect of red wine, each isolate was subjected to a 1:10 dilution of wine, during 120 seconds, at 25 ºC. Wine was found to exert an antilisterial effect, though a high phenotypic variability was observed among isolates - clinical isolates were found to be significantly more resistant to red wine than food isolates. Viable cells of one clinical strain (isolated from a listeriosis outbreak occurred in Portugal), collected after exposure to wine for 15 sec showed enhanced ability to invade the human intestinal Caco-2 cell line when compared to the corresponding unexposed control. This effect was not observed when the invasion test was done on two other isolates more resistant to wine. This is, to the best of our knowledge, the first study using a substantial number of L. monocytogenes strains from different origins and diverse phenotypic and genetic characteristics to study the susceptibility to wine. It is also innovative on assessing the influence of red wine on virulence traits of a foodborne pathogen. The results of this study give evidence that red wine can be seen as a significant barrier to the growth and survival of L. monocytogenes when in contact with contaminated food (food consumption scenario, for example).

Date of Award	27 Jun 2016
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	José António Couto (Supervisor), Vânia Ferreira (Co-Supervisor) & Tim Hogg (Supervisor)