Contributed by Poyin Chen
Listeria monocytogenes is a foodborne pathogen prevalent in environmental and food matrices including soil, fruit, and deli meats. This organism encompasses 13 serotypes, among which serotypes 1/2a, 1/2b, and 4b are most commonly associated with disease including gastroenteritis and abortions. Listeriosis accounts for less than 1% of foodborne illnesses worldwide yet carries the highest highest foodborne mortality rate (16%) with immunocompromised, pregnant, young, or old individuals at risk. When contracted during gestation, listeriosis results in miscarriage, stillbirths, or premature labor leading to infant mortality. Transmission is facilitated by its capability to proliferate at low temperatures and tolerate heat, acid stress, and salt stress, necessitating L. monocytogenes-specific sanitization protocols in processing plants.
Recent years have seen a spike in multistate outbreaks of listeriosis due to food contamination including deli meats, dairy, hummus, cantaloupe, and stone fruit, leading to recalls of contaminated products, resulting in millions of dollars in lost revenue. Genomic comparison of these outbreak strains with environmental isolates via whole genome sequencing will shed light on the genetic factors that potentiate L. monocytogenes virulence. Already we are expanding our knowledge of the genome organization and gene content of this pathogen.
Our recent sequencing and announcement of 306 L. monocytogenes genomes will allow for a greater understanding of L. monocytogenes biology and help to update current classification schemes.