Author:
Bo Andersen Jens,Roldgaard Bent B,Christensen Bjarke Bak,Licht Tine Rask
Abstract
Abstract
Background
Listeria monocytogenes has been implicated in several food borne outbreaks as well as sporadic cases of disease. Increased understanding of the biology of this organism is important in the prevention of food borne listeriosis.
The infectivity of Listeria monocytogenes ScottA, cultivated with and without oxygen restriction, was compared in vitro and in vivo. Fluorescent protein labels were applied to allow certain identification of Listeria cells from untagged bacteria in in vivo samples, and to distinguish between cells grown under different conditions in mixed infection experiments.
Results
Infection of Caco-2 cells revealed that Listeria cultivated under oxygen-restricted conditions were approximately 100 fold more invasive than similar cultures grown without oxygen restriction. This was observed for exponentially growing bacteria, as well as for stationary-phase cultures.
Oral dosage of guinea pigs with Listeria resulted in a significantly higher prevalence (p < 0.05) of these bacteria in jejunum, liver and spleen four and seven days after challenge, when the bacterial cultures had been grown under oxygen-restricted conditions prior to dosage. Additionally, a 10–100 fold higher concentration of Listeria in fecal samples was observed after dosage with oxygen-restricted bacteria. These differences were seen after challenge with single Listeria cultures, as well as with a mixture of two cultures grown with and without oxygen restriction.
Conclusion
Our results show for the first time that the environmental conditions to which L. monocytogenes is exposed prior to ingestion are decisive for its in vivo infective potential in the gastrointestinal tract after passage of the gastric barrier. This is highly relevant for safety assessment of this organism in food.
Publisher
Springer Science and Business Media LLC
Subject
Microbiology (medical),Microbiology
Reference28 articles.
1. Low JC, Donachie W: A review of Listeria monocytogenes and listeriosis. Vet J. 1997, 153: 9-29.
2. Authority EFS: Trends and Sources of zoonoses, zoonotic agents and antimicrobial resistance in the European Union in 2004. The EFSA Journal 2005 - 310. 2006
3. Foundation ILSIR, Institute RS: Achieving continuous improvement in reductions in foodborne listeriosis--a risk-based approach. J Food Prot. 2005, 68: 1932-1994.
4. Rocourt J, BenEmbarek P, Toyofuku H, Schlundt J: Quantitative risk assessment of Listeria monocytogenes in ready-to-eat foods: the FAO/WHO approach. FEMS Immunol Med Microbiol. 2003, 35: 263-267.
5. Norrung B: Microbiological criteria for Listeria monocytogenes in foods under special consideration of risk assessment approaches. Int J Food Microbiol. 2000, 62: 217-221.
Cited by
50 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献