Recent research indicates that not all strains of Listeria monocytogenes are equally virulent. Serotype 4b strains represent an unusually problematic Listeria clade because of their frequent implication in human illness. Their in-depth analysis of serotype 4b strains of L. monocytogenes included samples from food and food processing environments, humans, other animals, and the natural environment. The North Carolina State University team found that despite L. monocytogenes being ubiquitous in the environment, certain serotype 4b clones acquired unique genetic determinants associated with hypervirulence. One of these emerging clones has been responsible for three listeriosis outbreaks since 2014. Interestingly, these clones were not common in foods or food processing environments, but were over-represented in surface water samples.

NIFA supports this research through the Agriculture and Food Research Initiative.

Read the full journal article at PubMed.

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