A Molecular Marker for Evaluating the Pathogenic Potential of Foodborne Listeria monocytogenes

• Published in: The Journal of infectious diseases 2004-06, Vol.189 (11), p.2094-2100
• Main Authors: Jacquet, Christine, Doumith, Michel, Gordon, Jeffrey I., Martin, Paul M. V., Cossart, Pascale, Lecuit, Marc
• Format: Article
• Language: English
• Subjects: Bacteremia - microbiology; Bacterial Proteins - biosynthesis; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biomarkers; Central Nervous System Infections - microbiology; Female; Food Microbiology; Fundamental and applied biological sciences. Psychology; Humans; Immunoblotting; Infectious diseases; Life Sciences; Listeria monocytogenes; Listeria monocytogenes - metabolism; Listeria monocytogenes - pathogenicity; Listeriosis - microbiology; Medical sciences; Microbiology; Miscellaneous; Pregnancy; Virulence
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1086/420853

Background. Internalin mediates entry of Listeria monocytogenes into some human cultured cell lines and crossing of the intestinal barrier in transgenic mice expressing its receptor, human E-cadherin, in enterocytes. The relevance of these findings for humans is challenged by the observation that some L. monocytogenes isolates express a truncated nonfunctional form of internalin. Methods. We investigated expression of internalin by use of immunoblot assay in 300 clinical strains obtained in France in a single year and a representative set of 150 strains obtained from food products during the same period. Results. Clinical strains expressed full-length internalin far more frequently (288/300 strains [96%]) than did strains recovered from food products (98/150 strains [65%]; odds ratio, 12.73; 95% confidence interval, 6.27–26.34; ). P < 1×10−7 All 61 strains (100%) from pregnancy-related cases, 55 (98%) of 56 strains from patients with central nervous system infections, and 151 (93%) of 162 strains from patients with bacteremia expressed full-length internalin. All 110 strains belonging to serovar 4b, the most frequently implicated serovar in human listeriosis, expressed full-length internalin. Conclusions. This study demonstrates the critical role of internalin in the pathogenesis of human listeriosis. It provides a molecular explanation for the predominance of serovar 4b among clinical strains and supports the usefulness of studying the expression of internalin as a marker of virulence in humans.