Covers the general features of Listeria monocytogenes, including its tumbling motility at room temperature, weak beta-haemolysis and natural habitats. It then sets out a table of virulence factors such as internalins, listeriolysin O, phospholipases and ActA, followed by a stepwise account of pathogenesis from food entry to cell-to-cell spread. Epidemiology, a table of clinical forms by population group, diagnostic features, first-line and alternative treatment, and food-related prevention advice close the note.
Topic 69 of 113 in the MU Sofia syllabus for Microbiology (Medicine, Year 3). The free AceMed note covers it in 9 sections, about 182 words (2 min of reading), with 14 flashcards.
In this note
Genus Listeria – Listeria monocytogenes
General Characteristics
Virulence Factors
Pathogenesis
Epidemiology
Diseases
Diagnosis
Treatment
Prevention
General Characteristics
Morphology: Small, Gram-positive coccobacilli
Motility: Motile at room temperature (tumbling motility), non-motile at 37°C
Metabolism: Facultative anaerobe
Spore forming: Non-spore forming
Catalase: Positive
Haemolysis: Weak β-haemolysis on blood agar
Habitat: Widely found in soil, water, plants, and animal feces
Pathogenesis
1. Entry: Ingested via contaminated food
2. Invasion: Internalins mediate entry into M cells and epithelial cells
3. Phagosome escape: Listeriolysin O and phospholipases destroy phagosome membrane
4. Intracellular survival: Uses host actin (via ActA) to move through cytoplasm
