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United States Department of Agriculture

Agricultural Research Service

Research Project: Microbial Ecology of Human Pathogens Relative to Poultry Processing

Location: Bacterial Epidemiology & Antimicrobial Resistance Research

Title: Novel epidemic clones of Listeria monocytogenes, United States, 2011

item Lomonaco, Sara
item Verghese, Bindhu
item Gerner-smidt, Peter
item Tarr, Cheryl
item Gladney, Lori
item Joseph, Lavin
item Katz, Lee
item Turnek, Maryann
item Frace, Michael
item Chen, Yi
item Brown, Eric
item Meinersmann, Richard - Rick
item Berrang, Mark
item Knabel, Stephen

Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2013
Publication Date: 1/1/2013
Citation: Lomonaco, S., Verghese, B., Gerner-Smidt, P., Tarr, C., Gladney, L., Joseph, L., Katz, L., Turnsek, M., Frace, M., Chen, Y., Brown, E., Meinersmann, R.J., Berrang, M.E., Knabel, S. 2013. Novel epidemic clones of Listeria monocytogenes, United States, 2011. Emerging Infectious Diseases. 19(1):147-150.

Interpretive Summary: Listeria monocytogenes is a human pathogen that has been associated with a variety of foods including cantaloupe in a 2011 outbreak in the U.S. We gathered L. monocytogenes isolates from the cantaloupe outbreak, isolates from other food-related outbreaks, human clinical isolate collections, isolates known to be the same from several outbreaks and isolates from chicken further processing plants. All isolates were characterized using sophisticated molecular subtyping methods and compared to one another. It was discovered that the cantaloupe outbreak isolates matched L. monocytogenes isolates from food-related outbreaks in Canada, other world wide clinical collections and isolates from chicken further processing plants in the U.S. However, none of the cantaloupe isolates matched previously well characterized groups of isolates called epidemic clones. More research is required to determine how virulent strains of L. monocytogenes may become so widely disseminated.

Technical Abstract: This study determined whether four clinical and five food/environmental isolates associated with the 2011 U.S. cantaloupe listeriosis outbreak were previously identified outbreak strains, if they belonged to previously observed clonal complexes (CCs), to one of the five known epidemic clones (ECs) of Listeria monocytogenes, or if they otherwise represented novel ECs. Application of multiple sequence-based subtyping methods matched these nine cantaloupe outbreak isolates with those from other outbreaks in Canada, clinical cases detected worldwide over extended periods of time, and chicken processing plants in the U.S. None of the cantaloupe outbreak isolates belonged to previously defined ECs, but eight fell into globally disseminated CCs. One of the clinical isolates represents a novel serotype 1/2a outbreak strain. The other outbreak strains represent two novel ECs, defined here as ECVI, the first reported EC of L. monocytogenes in serotype 1/2b, and ECVII, the third recognized EC of L. monocytogenes in serotype 1/2a.

Last Modified: 10/16/2017
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