What are characteristics of Listeria monocytogenes?
Listeria spp. are small gram-positive rod (0.5–4 μm in diameter and 0.5–2 μm in length), non-spore-forming, facultative anaerobic, catalase-positive, and oxidase-negative organisms. Listeria has tumbling motility at 20–25°C due to peritrichous flagella.
How can you distinguish between Corynebacterium and Listeria?
Listeria species are catalase-positive, which distinguishes them from streptococci, and they produce a characteristic tumbling motility in fluid media at temperatures below 30°C, which distinguishes them from corynebacteria. Listeria monocytogenes is the only one of six Listeria species pathogenic for humans.
What makes the cell wall of Listeria monocytogenes interesting?
In addition, it also endows the cell with a specific cell shape and provides protection against mechanical stress. As in other noncapsulated gram- positive bacteria, the cell wall of L. monocytogenes is the outermost structure of the cell and acts as a scaffold in which different proteins anchor.
What makes Listeria unique from other bacteria?
Listeria monocytogenes. L. monocytogenes is one of the most virulent food-borne pathogens. It can flourish with or without oxygen and, unlike many other bacteria, can thrive and reproduce at temperatures as low as 0°C.
What is the shape of Listeria monocytogenes?
-positive rod shaped bacteria
The genus Listeria includes different species of ubiquitary present gram-positive rod shaped bacteria. The species Listeria monocytogenes causes severe diseases like meningitis and meningoencephalitis in humans.
Is Listeria monocytogenes Gram-positive or negative?
gram-positive
Listeria monocytogenes is a facultative, intracellular, gram-positive rod that is responsible for causing the infection listeriosis. Listeria causes severe infection in the elderly, neonates and the immunocompromised with only a self-limited gastrointestinal infection in the immunocompetent.
Is Listeria a Corynebacterium?
Listeria monocytogenes is the only pathogen in its genus. Importantly, it is catalase positive like corynebacteria, which it resembles morphologically, and unlike catalase-negative Group B streptococci, which it otherwise mimics when isolated on sheep blood agar.
What is the appearance of Listeria monocytogenes on blood sheep agar?
Cultivation 48 hours, aerobic atmosphere, 37°C. Colonies on blood agar are whitish gray and can be confused with streptococci, enterococci or diphtheroids (particularly after 24 hours of cultivation when beta-hemolysis is often quite weak).
Does Listeria monocytogenes have Pili?
Pili and fimbriae have not been described for L. monocytogenes. In general flagella may be used directly for attachment and colonization as an adhesin, or indirectly to provide movement of the cell to the surface to be colonized.
Is Listeria monocytogenes gram-positive or negative?
What are some facts about Listeria?
Listeriosis is a disease caused by Listeria monocytogenes. The disease primarily causes problems in pregnant women, newborns, and adults with a weakened immune system. Listeria bacteria are ubiquitous in the environment, and food-borne outbreaks have been detected worldwide.
What is the structure of Listeria?
The bacterium Listeria monocytogenes is shown to have a cell wall 200 Å in thickness, a limiting cytoplasmic membrane 110 Å in thickness, and a system of membranes in the cytoplasm. These internal membranes are numerous at the site of cell septum synthesis and can be closely associated with the nuclear material.
Is Listeria monocytogenes a Gram-positive rod?
Listeria monocytogenes is a facultative, intracellular, gram-positive rod that is responsible for causing the infection listeriosis. Listeria causes severe infection in the elderly, neonates and the immunocompromised with only a self-limited gastrointestinal infection in the immunocompetent.
What is the bacterial colony elevation of Listeria monocytogenes in blood agar plate?
Culture characteristics of Listeria The temperature range for growth is 3-45°C. But optimal temperature for growth is 30°C. In blood agar, it produces small, grey, translucent drop-like colonies surrounded by a small zone of indistinct beta hemolysis like streptococci but it is catalase test positive.
Do Listeria have flagella?
Listeria monocytogenes is a food-borne, gram-positive pathogen that uses flagella to increase the efficiency of epithelial cell invasion (A.
Is Listeria monocytogenes urease positive or negative?
Biochemical Test of Listeria monocytogenes
| Basic Characteristics | Properties (Listeria monocytogenes) |
|---|---|
| Spore | Non-Sporing |
| Urease | Negative (-ve) |
| VP (Voges Proskauer) | Positive (+ve) |
| Table of Contents Fermentation of Enzymatic Reactions Fermentation of |