Project description:Expression profiling by microarray was used with a murine listeriosis model to better understand increased susceptibility of preterm neonates to infection. We used DNA microarray to identify genes that were differentially expressed in liver of adult and neonatal Balb/c mice after listeriosis infection.
Project description:Invasive listeriosis is a severe foodborne infection in humans and is difficult to control. Listeriosis incidence is increasing worldwide, but some countries have implemented molecular surveillance programs to improve recognition and management of listeriosis outbreaks. In Germany, routine whole-genome sequencing, core genome multilocus sequence typing, and single nucleotide polymorphism calling are used for subtyping of Listeria monocytogenes isolates from listeriosis cases and suspected foods. During 2018-2019, an unusually large cluster of L. monocytogenes isolates was identified, including 134 highly clonal, benzalkonium-resistant sequence type 6 isolates collected from 112 notified listeriosis cases. The outbreak was one of the largest reported in Europe during the past 25 years. Epidemiologic investigations identified blood sausage contaminated with L. monocytogenes highly related to clinical isolates; withdrawal of the product from the market ended the outbreak. We describe how epidemiologic investigations and complementary molecular typing of food isolates helped identify the outbreak vehicle.
Project description:Expression profiling by microarray was used with a murine listeriosis model to better understand increased susceptibility of preterm neonates to infection. We used DNA microarray to identify genes that were differentially expressed in liver of adult and neonatal Balb/c mice after listeriosis infection. A murine listeriosis model was established. The methods for culturing and counting the Listeria monocytogenes (strain CNL 85/163) had been described in previous publications. The Listeria was injected intraperitoneally using a 1-mL U-100 insulin syringe with a 30 gauge needle. Doses of Listeria monocytogenes used were based on work by our laboratory showing that similar bacterial colony counts were obtained with 4.2 x 10^5 total Listeria per adult mouse and 150 Listeria per gram for 3 to 5 day old neonatal mice. In neonatal mice, great care was taken to void deep intraperitoneal injection towards the viscera, or across the central abdominal vessels. At specified time points, liver was removed upon animal sacrifice and immediately flash frozen in liquid nitrogen and stored at -80 degrees Centigrade. Three adult mice and three neonatal mice were used at each time point.