Seafood salad has been identified as a ready-to-eat food with a relatively high incidence of contamination by Listeria monocytogenes; however, little is known about the behavior of this pathogen in seafood salad as a function of product pH and storage temperature. To produce data towards the development of a predictive growth model, a 6-strain cocktail of L. monocytogenes was inoculated onto th...

Listeria monocytogenes causes invasive disease by crossing the intestinal epithelial barrier. This process depends on the interaction between the bacterial surface protein Internalin A and the host protein E-cadherin, located below the epithelial tight junctions at the lateral cell-to-cell contacts. We used polarized MDCK cells as a model epithelium to determine how L. monocytogenes breaches th...

Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monit...

In this study, we surveyed hogs (n = 300) as well as pork products (ground pork and raw chitterlings) for Listeria monocytogenes. Pig specimens collected before (tonsil swabs) and after slaughter (tonsils, lymph nodes, carcass swabs, and rectal contents) were examined for L. monocytogenes by enrichment with conventional enrichment broths followed by subculturing to selective agar. A multiplex p...

Listeria monocytogenes evades the antimicrobial mechanisms of macrophages by escaping from the phagosome into the cytosolic space via a unique cytolysin that targets the phagosomal membrane, listeriolysin O (LLO), encoded by hly. Gamma interferon (IFN-gamma), which is known to play a pivotal role in the induction of Th1-dependent protective immunity in mice, appears to be produced, depending on...

Ethidium monoazide (EMA) is a DNA cross-linking agent and eukaryotic topoisomerase II poison. We previously reported that the treatment of EMA with visible light irradiation (EMA + Light) directly cleaved chromosomal DNA of Escherichia coli (T. Soejima, K. Iida, T. Qin, H. Taniai, M. Seki, A. Takade, and S. Yoshida, Microbiol. Immunol. 51:763-775, 2007). Herein, we report that EMA + Light rando...

Listeria monocytogenes has been implicated in several listeriosis outbreaks linked to the consumption of presliced ready-to-eat (RTE) deli meats. The possible contamination of sliced RTE meats by L. monocytogenes during the slicing process has become a public health concern. The objectives of this study were to investigate the transfer phenomena of L. monocytogenes between a meat slicer and ham...

To investigate factors which modulate the entry of Listeria monocytogenes into mammalian cells, we have analyzed the role of Ca(2+). We show that L. monocytogenes induced Ca(2+) transients into the human Hep-2 epithelial cell line. The nonpathogenic species L. innocua or a L. monocytogenes mutant strain defective in listeriolysin O (LLO) production was unable to induce these calcium fluxes. Add...

This study investigated and modeled the behavior of Listeria monocytogenes in egg salad and pasta salad as affected by mayonnaise pH (3.8, 4.2, 4.6, and 5.0) and storage temperature (4, 8, and 12 degrees C). At each storage temperature, L. monocytogenes was able to grow in both salads regardless of the mayonnaise pH. The lag-phase durations (LPD) of L. monocytogenes in egg salad ranged from 33 ...

The human pathogen Listeria monocytogenes is susceptible to the β-lactam antibiotics penicillin G and ampicillin, and these are the drugs of choice for the treatment of listerial infections. However, these antibiotics exert only a bacteriostatic effect on this bacterium and consequently, L. monocytogenes is regarded as β-lactam tolerant. It is widely accepted that the phenomenon of bacterial to...