Micro 21: Listeria and Related Gram-Positive Bacteria

Clinical Deep Dives · Feb 17, 2026 · 44m

This episode explores Listeria monocytogenes and related aerobic, non–spore-forming Gram-positive bacilli. Drawing from Murray’s chapter, the focus is on Listeria’s distinctive ability to survive and replicate within host cells.

The narrative centres on its pathogenesis: ingestion via contaminated food, intestinal invasion, survival within macrophages, escape from the phagolysosome via listeriolysin O, and actin-based intracellular motility that allows cell-to-cell spread without extracellular exposure. This strategy explains its predilection for vulnerable populations - neonates, pregnant…