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P2-178 Listeria monocytogenes actA Polymorphism Isolated from Food, Carcass, and Human in South Korea

Tuesday, August 2, 2016
America's Center - St. Louis
Jimyeong Ha, Sookmyung Women's University, Seoul, Korea, The Republic of
Sejeong Kim, Sookmyung Women's University, Seoul, Korea, The Republic of
Hye-Min Oh, Sookmyung Women's University, Seoul, Korea, The Republic of
Yohan Yoon, Sookmyung Women's University, Seoul, Korea, The Republic of
Hee Soo Lee, Animal and Plant Quarantine Agency, Gimcheon, Korea, The Republic of
Hyang-Mi Nam, Animal and Plant Quarantine Agency, Gimcheon, Korea, The Republic of
Introduction: Listeria monocytogenes is capable of survival in various environments and highly pathogenic (mortality: 20-30%) foodborne bacteria. ActA is a bacterial membrane protein, which encoded by 268-bp or 385-bp actA genes, and it induces intracellular or intercellular spreading by actin filament.

Purpose: The objective of this study was to compare the pathogenicity of L. monocytogenes between 268-bp and 385-bp actA.

Methods: To confirm the actA polymorphism of L. monocytogenes isolated from food, carcass, and humans in South Korea, primers were prepared and analyzed with PCR. actA sizes were identified by electrophoresis. To compare the invasion efficiency into Caco-2 cells between two actA genes, each of the L. monocytogenes strains (OD625 = 0.01) were infected to monolayer Caco-2 cell [young (2 day old) versus old aged (10 day old)], followed by incubation in 5% CO2 at 37°C for 24 h. After incubation, the Caco-2 cells were treated with gentamicin and triton X-100, and L. monocytogenes cell counts were then enumerated on tryptic soy agar plus 0.6% yeast extract.

Results: The size of most domestic food and carcass isolates had 385-bp actA, but the size of most human isolates had 268-bp actA. In addition, L. monocytogenes strains with 385-bp actA showed obviously high Caco-2 cell invasion efficiency, compared to L. monocytogenes strains with 268-bp actA (P<0.05). However, the invasion efficiency of L. monocytogenes strains with 268-bp actA became similar to those of L. monocytogenes strains with 385-bp actA in old aged Caco-2 cell, compared to young aged Caco-2 cell.

Significance: These results suggest that the size of actA may be related to L. monocytogenes invasion efficiency.

Back to: Poster Session 2 – Low-water Activity, Laboratory and Detection Methods, Epidemiology, Produce, Pre-harvest, Dairy and Beverages, Food Defense, General Microbiology
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